 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| PhotoKB HomeDiscussion Groups Digital Photography Digital PhotoDSLR CamerasZLR CamerasPoint & Shoot CamerasFilm Photography 35 mmLarge FormatMedium formatDarkroomFilm and LabsOther EquipmentPhoto Technique Nature PhotographyPeople PhotographyTechnique GeneralGeneral Photo Topics General TopicsAustralian PhotographyUK PhotographyDirectoryPhoto Clubs |
Photo Forum / Digital Photography / DSLR Cameras / January 2005Equivalent focal lengths and crop factors...
Haven't read here for a while. Wondered when all this would surface here. Well, it has and it won't go away, so maybe some clarification is in order. This whole subject is what happens when the tech geeks and the arty types fail to communicate, things get lost in the cracks, important things. We have focal lengths, equivalent focal lengths, angles of view, image area, depth of field, frame composition, perspective... real hodge podge! Two things that weren't considered, and are important, are: 1) The interface between photographer and camera, the view finder. The one thing that does not ever change is the natural field of vision of an individual, the inherent angle of view. That's the bench mark. Now, an individual looks throught the viewfinder of a camera. If it's an SLR, the viewfinder presents a perceived angle of view that does not change. It does not allow the viewer to perceive the change in the lens' angle of view. Look through a rangefinder with interchangeable lenses. Different marked off fields of view, so the viewer can perceive the changed angle of view. Since the viewfinder is not part of the lens' optical train, the perceived angle of view *of the viewfinder* does not change, and the sense of the differences between the "perspectives" of different focal length lenses is not apparent. What happens with the SLR is that the eye is fooled into thinking that what he/she sees has changed, when it has in fact not changed at all. How that happens is obvious: A "standard" lens is one that will present to the viewfinder what the eye would see if the viewfinder were a simple window, unaltered by an optical train. One can often shoot with both eyes open using a standard lens, without suffering the effects of difference perceived by each eye. Can't do that with a telephoto or wide angle. Well, at least I can't... So what is going on here is that the camera user comes to identify the perceived effect of different focal lengths, and comes to associate particular differences with particular focal length lenses. And this is why the persistent popularity of the "equivalent focal length". Are the tech geeks right? Yep, they are. Is that important? Yep, it is. Why? Because some things don't change, and one of them is DOF. Another is relative distortion of the scene image. Both of these are very important, of course. Which leads to the second thing. 2) Perspective. It turns out that there are two different definitions in common usage. Now never mind the dictionaries, we know this without consulting them. The first and literal definition is "what you see from where you are". Here, we're talking about what you can and cannot see from a point of view, which changes when the point of view is changed. You change your viewing position, and some things that were not visible become so, and some things that were visible, now are not. That's not the same as the second definition, which has to do with the relative size of viewed objects. The problem here is that this second definition can easily be assumed to be a subset of the first: Things get larger as one gets closer; given the natural angle of view, moving closer makes an object take up more room in the field of vision. However, the relative size of objects in the scene can be made independent of the point of view created perspective. That is easily accomplished with optics (and recorded in camera) by distorting the scene optically. Artists do this all the time to achieve the effects they want. They call it a change in perspective, and their use of the term is what has established the second definition. Artists use cameras, and so photography uses both definitions. What's the problem? Well, there's a "gotcha!!" lurking here. And that is that a photographer expects the camera to record reality as it is, because that's what cameras are supposed to do. Right? Well, that's as may be, but the reality is that no, they do not. What they do is record an optically produced image, whatever that may be, and the unwary can really get confused when optical distortion is not acknowledged. Here's the reality check: If things change in relative size, expect different things to be visible. If different things are not visible, you're looking at an optically produced distortion. And that's how you tell which definition is being used. The arty types don't care about all this "semantic detail". Perspective change via distortion and perspective change via change in position are deemed equivalent for their purposes, or so it seems. Not being an arty type I wouldn't know for sure. The tech geeks insist that they are entirely different things and should never be confused. Perspective change is never produced by a change in focal length, so they say, and according to the first definition, they're right. And for them, apparently, that's all that matters. Not being a tech geek, I wouldn't know for sure. The truth is that both are missing an important aspect of this business, and that is the effect these changes have on the viewer. Trouble is, both types are also viewers, and because of this lack of complete understanding, cannot come to an agreement about what's what. There are some truths in some of the statements made, of course. You cannot change perspective of the first definition by changing focal lengths. But it's equally true that you certainly can change perspective by the second definition by changing focal lengths. What makes both true is that one makes the change by distortion and the other does not. As a camera user of some experience, you can equate the angle of view provided by a focal length in one format with the perceived angle of view in another. But the lenses themselves do not change focal length, nor do they change angle of view. Enter the crop factor. Incidentally, an optical train is an optical train whether displaying a recorded image, or recording a displayed image. Optical crop is optical crop. No, the two trains are not designed alike, but that's irrelevant. For what its worth, that is... Maybe if you guys would think all this through, you would realize that reality does not change, and that differences in opinion are the result of different perceptions. You want to be completely right? Better think these things through a bit better. Otherwise, all you guys have stuff to learn, and are better off listening to each other and trying to figure out what you've missed. Myself included, of course. I walk the walk I talk: tell me where I screwed up here, or what I missed and I'll willingly stand instructed. Will D. > You cannot change perspective of the first definition by changing focal > lengths. But it's equally true that you certainly can change > perspective by the second definition by changing focal lengths. What > makes both true is that one makes the change by distortion and the other > does not. The change you are making in 'distortion' are not changing the perspective. Were this the case, then the objects present in both frames would have different 'perspectives' (which they do not). The 'perspective' here is created by including other objects around the edges which were not included in the first frame (or removing them). B "A "standard" lens is one that will present to the viewfinder what the eye would see if the viewfinder were a simple window, unaltered by an optical train." I don't believe this was true on a 35mm film as the standard is 50mm when approx a 70mm will give 1:1, but with a 1.6 crop with most digitals it may now be right ! > Haven't read here for a while. Wondered when all this would surface > here. Well, it has and it won't go away, so maybe some clarification is [quoted text clipped - 129 lines] > > Will D. > "A "standard" lens is one that will present > to the viewfinder what the eye would see if the viewfinder were a simple [quoted text clipped - 3 lines] > approx a 70mm will give 1:1, but with a 1.6 crop with most digitals it may > now be right ! 70mm will give 1:1? How can you possibly make this statement given the huge range of viewfinder magnifications available? B Let me try to explain. If I look through my EOS 3 using a 24-85mm lens and compare the view through the viewfinder with the view with my eyes I get the same size image direct or through viewfinder when the lens is 70mm. If I try my EOS-10D the setting is between 50 and 55mm. Looking at the new Nikon F6, as an example, they quote viewfinder magnification as .74 with 50mm and the EOS 1Ds Mk2 is .70 at 50mm. The diagonal coverage of a 50mm is 40deg and a 70mm is 29deg giving a maginification of 1.38. 1.38 x 0.7 = .96 and 1.38 x .74 = 1.02 both near enough to 1 for me. Obviously as you say if there are other magnifications then this doesn't work, ie Minolta 7 is 0.8 at 50mm, but I've always 70mm to be correct for my cameras. Certainly not the standard 50mm !! Cheers >> "A "standard" lens is one that will present >> to the viewfinder what the eye would see if the viewfinder were a simple [quoted text clipped - 9 lines] > > B > Let me try to explain. > [quoted text clipped - 5 lines] > Looking at the new Nikon F6, as an example, they quote viewfinder > magnification as .74 with 50mm and the EOS 1Ds Mk2 is .70 at 50mm. Not a particularly wide selection. The high-end bodies in both ranges tend to have fairly similar eyepiece magnifications. > The diagonal coverage of a 50mm is 40deg and a 70mm is 29deg giving a > maginification of 1.38. [quoted text clipped - 6 lines] > work, ie Minolta 7 is 0.8 at 50mm, but I've always 70mm to be correct for my > cameras. Things vary a bit more with some of the manual focus bodies. > Certainly not the standard 50mm !! The 'standard' lens is defined in terms of closeness to the diagonal of the format in question. With such a lens (actually around 45mm on 35mm format) coupled with that format, you'll end up with a print whose perspective looks natural at a normal viewing distance. In contrast, shorter lenses will produce prints whose perspective looks odd unless you're closer, and longer ones odd images unless you are further away. B >"A "standard" lens is one that will present >to the viewfinder what the eye would see if the viewfinder were a simple [quoted text clipped - 3 lines] >approx a 70mm will give 1:1, but with a 1.6 crop with most digitals it may >now be right ! I guess you grew up with the modern auto-everything cameras, and their tiny little viewfinders. Try looking through the viewfinder of an older camera some time; something like a Nikon F2, or even just a Pentax Spotmatic. Unfortunately when more and more camera automation came along, the makers had a problem. They were stuck with three choices: to not present details of what the camera was doing in the viewfinder (unacceptable in those days; photographers might accept some level of automation, but they knew enough not to trust the camera without verification); to present the information alongside the traditional viewfinder (expensive, and difficult to use for people wearing eyeglasses), or to reduce the size of the viewfinder image to free up some space for all the additional display. The modern digitals have, quite often, chosen to shrink the usage even more (presumably because they share viewfinder optics with a film sibling); the D70 still only has a magnification of 0.8 with a 50mm lens. Even the D2X only gets a little better, at 0.86X. Canon are slightly better; the 0.70 of the 1DsII is somewhat understandable because of the larger sensor, and the 300D matches the D70 at 0.8x. The 10D and 20D are both close to 0.9x, which is better than the far more expensive D2! But the best viewfinder I've seen in a DSLR is in the Pentax *ist-D/DS. These both have viewfinder magnifications of 0.95. Considering the fact that the *ist-DS is in the same price bracket as the D70 and 300D, it's quite impressive to see a viewfinder that large in a budget(sic) DSLR. Disclaimer: I own a *ist-D. But I've used several of the alternatives (including a D1, a 10D, and a D100), so I speak from personal experience. (repost - server prob.) > "A "standard" lens is one that will present > to the viewfinder what the eye would see if the viewfinder were a simple [quoted text clipped - 3 lines] > approx a 70mm will give 1:1, but with a 1.6 crop with most digitals it may > now be right ! Think you could not top post and snip away what is not needed? The "normal" view with a cropped sensor (1.5) would be about 30 to 35mm, not 70mm. Cheers, Alan.  Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: there's no such thing as a FreeLunch. I never said 'normal' (whatever that is) was 70mm with a 1.5 crop. All I know is if I look through my EOS-1D with approx 50mm lens the image in the viewfinder is the same size to my eye as looking without the camera, 1.5 x 50mm = 75mm. Cheers > The "normal" view with a cropped sensor (1.5) would be about 30 to 35mm, > not 70mm. . try EOS-10D not 1D, my typo >I never said 'normal' (whatever that is) was 70mm with a 1.5 crop. All I >know is if I look through my EOS-1D with approx 50mm lens the image in the >viewfinder is the same size to my eye as looking without the camera, 1.5 x >50mm = 75mm. > > Cheers > You cannot change perspective of the first definition by changing focal > lengths. But it's equally true that you certainly can change > perspective by the second definition by changing focal lengths. What > makes both true is that one makes the change by distortion and the other > does not. The relative size of objects with distance does not change with focal length. You can easily prove this for yourself with the usual experiments. Take two pictures from exactly the same point, one with a telephoto and one with a wide angle, not moving the camera in between. Crop the wide angle shot so that its framing matches the telephoto shot, and you will see that they are identical. There is no distortion, and there is no perspective change by either of your definitions. SignatureJeremy | jeremy@exit109.com >> You cannot change perspective of the first definition by changing focal >> lengths. But it's equally true that you certainly can change [quoted text clipped - 10 lines] > they are identical. There is no distortion, and there is no perspective > change by either of your definitions. This is true, but you miss the entire point: It is the perceived angle of view a) through the viewfinder, and b) when viewing a print in the normal manner, that creates this effect. The viewfinder enforces a single angle of view, and so does the standard print viewing practice. The latter would have you hold the print at approximately the distance equal to the diagonal of the print itself. If you want to complete the experiment you cite properly, you should view the prints at the appropriate distances. For the wide angle shot, put your nose on the surface of the print, or thereabouts. For the telephoto shot, stand back across the room. In both cases, the distortion effect is cancelled. Of course, that might not serve the intent of the photographer... But you cannot do this with your viewfinder, and so cannot cancel the perceived distortion effect at that point in the process. Again, think this through to the end, and you'll likely answer your own questions. Will D. > If you want to complete the experiment you cite properly, you should > view the prints at the appropriate distances. For the wide angle shot, > put your nose on the surface of the print, or thereabouts. For the > telephoto shot, stand back across the room. In both cases, the > distortion effect is cancelled. Of course, that might not serve the > intent of the photographer... Except that the wide-angle shot, once cropped, *becomes* a telephoto shot. Cropping it is, for the purpose of the experiment, the same thing as using a longer focal length -- this is the conclusion of the experiment, not the premise, but in the end, zooming in is just a way to optically crop the image. The relative sizes of objects according to distance is a function of the distances involved -- the lens can't change them, unless it's distorting them due to optical defects, which doesn't really count. When you look through a long telephoto lens, it may look like the distances are compressed, but that is an illusion coming from the fact that you are seeing the scene in a way your unaided eye cannot. The perspective is actually identical to what you see with any focal length. SignatureJeremy | jeremy@exit109.com >> If you want to complete the experiment you cite properly, you should >> view the prints at the appropriate distances. For the wide angle shot, [quoted text clipped - 8 lines] > experiment, not the premise, but in the end, zooming in is just a way > to optically crop the image. Well, if the point you are making is that photographic optical trains do not introduce gratuitous distortion, you are correct, AFAIK. But that does not address the issue I raised. > The relative sizes of objects according to distance is a function of > the distances involved -- the lens can't change them, unless it's > distorting them due to optical defects, which doesn't really count. Yes, we can assume no gratuitous distortions, I think. > When you look through a long telephoto lens, it may look like the > distances are compressed, but that is an illusion coming from the fact > that you are seeing the scene in a way your unaided eye cannot. The > perspective is actually identical to what you see with any focal length. An illusion is an apparency that is the function of the interpretive mind, which is classically dispelled by blinking one's eyes and taking another look. Big noses and tiny ears in portraits taken with wide angle lenses cannot be dispelled by blinking one's eyes. Compared to what one sees with unaided vision, they constitute distortions. I defined the second usage of the term "perspective" as caused by distortion, because we are accustomed to gauging our position in our environment, in part, by the relative size of the objects around us. You can make the case that this second definition is an illusory corollary of the first, but the fact is that artists have long used this second definition and thus it is customary usage in photography. Will D. > An illusion is an apparency that is the function of the interpretive > mind, which is classically dispelled by blinking one's eyes and taking > another look. Big noses and tiny ears in portraits taken with wide > angle lenses cannot be dispelled by blinking one's eyes. Compared to > what one sees with unaided vision, they constitute distortions. But they are not a product of focal length, nor is the amount of such visual distortion a function of focal length. It is not the wide-angle lens that causes this. SignatureJeremy | jeremy@exit109.com >> An illusion is an apparency that is the function of the interpretive >> mind, which is classically dispelled by blinking one's eyes and taking [quoted text clipped - 5 lines] > visual distortion a function of focal length. It is not the wide-angle > lens that causes this. Would you please explain this phenomena, then? Perhaps we all might learn something here. Will D. >>> An illusion is an apparency that is the function of the interpretive >>> mind, which is classically dispelled by blinking one's eyes and [quoted text clipped - 11 lines] > > Will D. Seems to me it has been esplained, discussed, and demonstrated to within an inch of its (apparently eternal) life. And without malice or meanness, just so at least one of us learns something, it's "this phenomenon", "these phenomena". Merry Christmas. SignatureFrank ess <snip> > Seems to me it has been esplained, discussed, and demonstrated to within > an inch of its (apparently eternal) life. > And without malice or meanness, just so at least one of us learns > something, it's "this phenomenon", "these phenomena". > > Merry Christmas. ----------- Also, the word is spelled "explained" not "esplained". We all make errors from time to time, don't we? Merry Christmas to you and your family. Don F > <snip> >> Seems to me it has been esplained, discussed, and demonstrated to [quoted text clipped - 10 lines] > Merry Christmas to you and your family. > Don F Well, YOU can esplain that to Ricky and Lucy. Dipsh*t picayune spelling cop. How do you feel now? Merry Christms to you. (Big smiley face) Signature-- Frank ess <snip> > Well, YOU can esplain that to Ricky and Lucy. Dipsh*t picayune spelling > cop. How do you feel now? > > Merry Christms to you. (Big smiley face) ----------------- Sad! I feel fine, BTW. Thanks for asking. Don F [so-called wide-angle distortion] >> But they are not a product of focal length, nor is the amount of such >> visual distortion a function of focal length. It is not the wide-angle >> lens that causes this. > > Would you please explain this phenomena, then? Perhaps we all might > learn something here. I'm not sure how many different ways it can be explained before a few people stop refusing to believe it. It is a product of the camera position relative to the subject. Some people *think* is has to do with the lens focal length because, when using a wide angle lens, you get closer to the subject in order to get the framing you want. But it is getting closer that does it. If it had to do with focal length, you would get big noses and all that stuff shooting a full-length picture of someone from 15 feet away with a point and shoot digicam, since the lens would be less than 10mm. But you don't, because it doesn't. SignatureJeremy | jeremy@exit109.com > [so-called wide-angle distortion] >>> But they are not a product of focal length, nor is the amount of such [quoted text clipped - 16 lines] > a point and shoot digicam, since the lens would be less than 10mm. > But you don't, because it doesn't. What we have here is a failure to communicate, I must suppose. As I originated the issue, I'll take responsibility for that failure, though for the life of me I cannot see what it is you do not understand about what I said. Everything you have said is true, and I have agreed with you. If that were all that were involved, this entire discussion would not be an issue at all. Yet this issue continues to arise, over and over again. There is more to the matter than just lens focal length. Because you cannot grasp this, you cannot resolve the matter fully. You think you have a pat answer that has been established long since, and you are correct as far as you go. Problem is, you don't include the viewer in the system you're analyzing. In any case, I've done due diligence here. Will D. ><snip> > An illusion is an apparency that is the function of the interpretive > mind, which is classically dispelled by blinking one's eyes and taking > another look. Big noses and tiny ears in portraits taken with wide > angle lenses cannot be dispelled by blinking one's eyes. Compared to > what one sees with unaided vision, they constitute distortions. This effect - small ears and big noses - is because the viewing distance of the photo is wrong. The 'correct' viewing distance of any image is equal to the focal length of the taking lens times the subsequent magnification applied to the image. At this distance - and only this distance - the relative sizes of objects in the photograph will correspond with what was seen by the lens when taking the shot. If you view the image from too close, the perspective appears flattened, and from too far away the perspective appears exaggerated. This is the source of your ears/nose problem. Example: a portrait taken with a 24mm lens on 35mm film, and enlarged to 10x8 will require a viewing distance of 24mm x 8 (the degree of enlargement). This comes out to about 7.5 inches, much closer than one usually views a 10x8 print. However, if you do view the image at that distance, the perspective will look right. One definition of a 'normal' lens is when images from that lens, viewed at the usual distance for the size of print, appears to have normal perspective. > I defined the second usage of the term "perspective" as caused by > distortion, because we are accustomed to gauging our position in our > environment, in part, by the relative size of the objects around us. > You can make the case that this second definition is an illusory > corollary of the first, but the fact is that artists have long used this > second definition and thus it is customary usage in photography. This follows from my above comments Colin >><snip> >> An illusion is an apparency that is the function of the interpretive [quoted text clipped - 30 lines] > > Colin Finally, someone has thought this at least beyond the regurgitated dogma handed out in these parts. Kudos! I'm curious to know if you thought this was a difficult matter, or was it obvious to you that part of the story wasn't being considered? Will D. > >><snip> > >> An illusion is an apparency that is the function of the interpretive [quoted text clipped - 38 lines] > > Will D. Sorry about not snipping here, but I couldn't without losing the trail. I grew up with photographic matters way back in the 1950's, when the Ilford Manual and similar publications were the bible of photography. All of this perspective, DoF, etc. became an integral part of my photographic experience, and is just second nature to me now. So, it isn't difficult, I don't have to think about it, it's just 'there'. I don't mean to sound boastful or arrogant, it's just the results of lifetime learning and doing. Colin. <snip> > Sorry about not snipping here, but I couldn't without losing the trail. No problem. I just turn the shears lose :) > I grew up with photographic matters way back in the 1950's, when the > Ilford Manual and similar publications were the bible of photography. [quoted text clipped - 5 lines] > > Colin. Sounds like me, I guess. I've had schooling, but these are the obvious basics, seems to me. I read Ansel's books, and Dad had a sheet film camera. Much the same sort of thing as the stuff in Ilford and Kodak books, I suppose. I just figure that answers that blow off questions aren't good answers. To me, a valid answer has to satisfy the existence of the question, if nothing else, and the answers given hereabouts to newbies about perspective don't do that. Anyway, glad to see agreement that this is all basic photographic knowledge that anyone should understand from a bit of reading and experience. Will D. > Finally, someone has thought this at least beyond the regurgitated dogma > handed out in these parts. Kudos! > > I'm curious to know if you thought this was a difficult matter, or was > it obvious to you that part of the story wasn't being considered? I still can't figure out what it is you're getting at. This discussion always starts with someone putting forth the misconception that perspective is a function of focal length. It is not. It still is not even taking into account what you're talking about here. Moreover, I am unable to figure out how what you're talking about here matters in any way whatsoever to the topic. Now, granted, I've tried the "correct viewing distance" thing before, and I just can't see it -- I can look at a picture shoved right up against my nose or from across the room, and it looks exactly the same to me. I am unable to see this effect. However, I'm willing to accept that everyone else can -- but even with that accepted, I can't see what it has to do with anything. It doesn't change the perspective of the image. It doesn't affect the image in any way whatsoever. SignatureJeremy | jeremy@exit109.com >> Finally, someone has thought this at least beyond the regurgitated dogma >> handed out in these parts. Kudos! [quoted text clipped - 7 lines] > that perspective is a function of focal length. It is not. It still is > not even taking into account what you're talking about here. Well okay, let me give this another try, then. The dogma is that perspective has a single definition: the view from a location. A change in the former necessitates a change in the latter. Also included in this dogma is the assertion that this single statement is all that is relevant. I'm claiming that this last assertion is false. Here's why: There are arguably two different definitions of perspective, though they are related. The first and dogmatic is the scientific definition having to do with the physics of optical trains, etc. The second, and here ignored, definition is that used by artists, and has to do not with the science of optics, but with the experience of the observer. In support of this contention is the fact that painters produce images using only their own eyes and dexterity with a paint brush. They deliberately create artistic perspectives that may or may not be optically reproducible, and they do so to affect the viewer in some intended manner. It's not crystal clear that all artists see this the same way, but it seems to me that they all are using the same human facility, which is that we orient ourselves in our environment by means of an (automatic) analysis of perceived perspective. In this, we note what we can and cannot see as compared to what we know exists, and we note the relative perceived size of objects that we have had occasion to measure objectively (if only from some standard distance, etc). Artists alter our sense of orientation wrt the scene in their work. And so forth. So these two definitions have a common basis, and that is the human experience. One, the scientific version, is specific as a definition of objective phenomenon. Cameras can and do have a perspective independent of the user. The other, the artist's version, is specific as a definition of a human experience, which is our most common way of locating ourselves in our environment. The important thing about this, in this thread, is that artistic perspective can be distorted, and any distortion does affect the viewer, though perhaps not predictably in all cases. Having argued this dual definition, what I've said is that the invariant angle of view of an SLR viewfinder creates such a distortion, and that newbies trying to figure all this out for themselves usually do not "get" this fact. The dogma does not satisfy their experience because it either ignores or refutes that experience, neither of which is reasonable as far as I'm concerned. Photographers are, or can be, artists, and the use of the second definition is perfectly legitimate in photography, and so the claim that it is not, or does not exist, is invalid and such an assertion is false. > Moreover, I am unable to figure out how what you're talking about here > matters in any way whatsoever to the topic. Now, granted, I've tried the [quoted text clipped - 5 lines] > change the perspective of the image. It doesn't affect the image in any > way whatsoever. The topic here is not the science of optics, it is the experience of the effect of uncompensated angle of view presentations, which has much to do with the art of photography. The topicality is based on the fact that new people sometimes consider DSLRs as a way of getting out of snapshooting and into photography, and come here to learn. Part of that experience has to do with addressing questions directly that they have ignored before. This issue is one of those questions, which is why my OP. You say the print looks exactly the same regardless of viewing distance, and so it should. The question is whether or not it looks natural, or does it look distorted: the relative size of objects not corresponding to what might be expected, creating the impression of exaggerated or compressed distances. Of course, maybe this is irrelevant to you, but it doesn't seem irrelevant to newbies, at least in my experience. Here's a question for you. You've noticed the engraved message in the passenger side mirrors of modern cars? It says something like "Warning! Objects in mirror are closer than they appear!" Do you consider the image in such mirrors to be distorted? Most people do, I think. Do you think this is important? If you don't, why not? Or maybe better yet, if you do, how do you explain this? Will D. > In this, we note what we can and cannot see as compared to what we know > exists, and we note the relative perceived size of objects that we have > had occasion to measure objectively (if only from some standard > distance, etc). Artists alter our sense of orientation wrt the scene in > their work. And so forth. Yes, I agree; an artist using a media where the image is created from "scratch" can play with perspective as you say. However, a photographer cannot, so I don't see it as terribly applicable. However, although a photograph does only display what is actually visible, it doesn't include enough information for a human to reproduce the experience of seeing the scene in person, in terms of orienting himself and determining what goes where. Our eyes and brains use things that aren't included in a flat photograph to do that. This allows some degree of optical illusion in perspective, but still only in a way that doesn't change what is actually there. The camera records what is visible from a certain viewpoint, and that's it. > Having argued this dual definition, what I've said is that the invariant > angle of view of an SLR viewfinder creates such a distortion, and that > newbies trying to figure all this out for themselves usually do not > "get" this fact. The dogma does not satisfy their experience because it > either ignores or refutes that experience, neither of which is > reasonable as far as I'm concerned. I also agree with this, but I think we differ on an underlying cause. In the old days of film, it was not a problem to describe perspective in terms of focal length, because a given focal length always meant the same thing to 35mm camera users. Nowadays, you simply cannot use focal length to describe perspective, because focal length can't describe the angle of view on a digital camera -- lenses of the same focal length can have very different views on different cameras, even the exact *same* lens used on different cameras. Unfortunately, lots of stuff, including written stuff in formerly-authoritative texts, still exists talking about perspective of certain lenses, and all of that stuff is now simply not true. If I put my 50mm lens on my 35mm SLR, and then put it on my digital SLR, it will not give me the same field of view on both cameras. On the digital it will behave exactly the same as a 75mm lens would on the 35mm camera, with regard to field of view (not depth of field, which is a whole other topic). If you want to consider perspective as a function of focal length, you must then think of it as a 75mm lens when using it on the digital SLR (at least a Nikon one) because that's how it will work. Given identical framing (and thus differing camera-to-subject distance) with that lens on the two cameras, the perspective will be different. So, I think people get confused because they have learned about perspective either back when you *could* describe angle of view by focal length, or from things written at that time. Back in the day, if you were writing for 35mm film users, you could say that 50mm is a "normal lens" and be right. You can't do that any more because it's not going to be right. > You say the print looks exactly the same regardless of viewing distance, > and so it should. The question is whether or not it looks natural, or > does it look distorted: the relative size of objects not corresponding > to what might be expected, creating the impression of exaggerated or > compressed distances. That's what I mean. To me, a wide-angle shot with "distortion" at the edges (I put "distortion" in quotes because it's not really distortion, and I've been scolded for using that word to describe it here already, but I can't think of a better word to use) still looks identically distorted no matter where the print is relative to my eyes. But since everyone else says it doesn't, fine; this is something I haven't learned to see, like those pictures in the mall with all the dots that are supposed to become something if you stare at them long enough, but which always (to me) just look like a bunch of dots. But if that does work, it works because you're changing the angle at which you're seeing certain parts of the scene, which is basically the same thing you do when you move the camera. The wide-angle "distortion" is caused by seeing parts of the scene at different angles, but then projecting that resulting image onto a flat surface. So that doesn't mean that something other than viewpoint changes perspective; you're just changing the viewpoint. > Here's a question for you. You've noticed the engraved message in the > passenger side mirrors of modern cars? It says something like "Warning! > Objects in mirror are closer than they appear!" Do you consider the > image in such mirrors to be distorted? Most people do, I think. Do you > think this is important? If you don't, why not? Or maybe better yet, > if you do, how do you explain this? That is distortion, due to the mirror being convex. So? It's basically the same thing; it's a "wide angle" mirror. SignatureJeremy | jeremy@exit109.com > That's what I mean. To me, a wide-angle shot with "distortion" at the > edges (I put "distortion" in quotes because it's not really distortion, [quoted text clipped - 5 lines] > supposed to become something if you stare at them long enough, but > which always (to me) just look like a bunch of dots. I think you'd be able to see it much more easily if you closed one eye. Your brain has various compensatory mechanisms, you know. B >> In this, we note what we can and cannot see as compared to what we know >> exists, and we note the relative perceived size of objects that we have [quoted text clipped - 14 lines] > there. The camera records what is visible from a certain viewpoint, and > that's it. Well, to the extent that people learn to ignore "optical illusion in perspective", it becomes (or can become) of less importance that perhaps you inferred from my comments. Certainly people who know little or nothing about photography easily ignore the issue. But my point was that newbies trying to extent their photographic knowledge and skills will come to ask what's going on, and to state that nothing is going on is to suggest to them that what they see is non-existent. And that's not the case. >> Having argued this dual definition, what I've said is that the invariant >> angle of view of an SLR viewfinder creates such a distortion, and that [quoted text clipped - 30 lines] > for 35mm film users, you could say that 50mm is a "normal lens" and be > right. You can't do that any more because it's not going to be right. I'm talking about newbies that have never used an SLR of any kind. They know nothing of the traditional focal length / angle of view correspondence. That's only for people who've used an SLR enough to know better. >> You say the print looks exactly the same regardless of viewing distance, >> and so it should. The question is whether or not it looks natural, or [quoted text clipped - 11 lines] > supposed to become something if you stare at them long enough, but > which always (to me) just look like a bunch of dots. I use the word distortion without quotes because that's what it is. It's not an optical illusion at all. It's what happens when one tries to force one angle of view into another angle of view. And you're right when you observe that the print looks equally distorted from any viewing distance if, and probably only if, you cannot suspend your sense of current physical environment enough to "be with/in" the scene displayed by the print. I've no idea what percentage of people can't do that, but I've got to assume that a goodly percentage can, else visual art would not be the universally appreciated commodity it has long been. > But if that does work, it works because you're changing the angle at which > you're seeing certain parts of the scene, which is basically the same [quoted text clipped - 3 lines] > mean that something other than viewpoint changes perspective; you're > just changing the viewpoint. Well, yes, of course. The scientific definition of perspective always obtains. As far as flat surfaces are concerned, one might think of the observed image as an image plane, but I'm not clear that this is really relevant. In one case it's the ground glass, and the other it's a print surface, but that doesn't mean that the viewer stops trying to extract depth information. And it's the effect on the viewer that is primary to my original statement. And it's at that point that the second definition becomes relevant. >> Here's a question for you. You've noticed the engraved message in the >> passenger side mirrors of modern cars? It says something like "Warning! [quoted text clipped - 5 lines] > That is distortion, due to the mirror being convex. So? It's basically > the same thing; it's a "wide angle" mirror. Exactly. It's one angle of view being forced into another angle of view, which is the cause of the distortion. Now, here the flat surface issue is relevant. Do you see the mirror as a flat surface? I don't. I'm accustomed to extracting depth information from a mirror because normally the mirror is planar. Of course there is an adjustment to be made because of the viewer to mirror distance, but most people are able to make that adjustment automatically, I think. I think we've come to agree that the issue is real, whether or not it is relevant here in general or specifically in the case of newbies learning. We can debate the particulars and details, but it's that agreement of the reality of the issue that I was seeking. Will D. > This discussion always starts with someone putting forth the misconception > that perspective is a function of focal length. It is not. It still is [quoted text clipped - 12 lines] > -- > Jeremy | jeremy@exit109.com That was me who put that forward, Jeremy. Perhaps Jeremy, your interpretation of 'perspective' as applied to photographing portraits is different to the interpretation of Photographers who actually take portraits for a living? I made the mistake of presuming this group was frequented by photographers and artistic people who had natural perspective appreciation as part of their makeup. I was wrong. This thread demonstrates that a new (let me call it 'breed') of technocrats has emerged into what has always previously been an artistic appreciation of the many aspects of art. Artists are more inclined to focus on the final result of what they do. Their cameras are only tools they use to achieve a photograph. They know a 100 mm lens will produce a portrait with better 'perspective' than your assertion that a 20mm one can too. Many could make the portrait with or without a camera. Technocrats are digital deviates. They embrace photography for it's technology as much as it's picture taking ability. The statements you made above, very clearly demonstrate you have little of the artist in you and a lot of the technologist. I still use a portrait lens for portraits because 80, 100 mm focal length lenses produce a better perspective to the photograph. That is my statement. I learned it from masters of photography, probably before you were born and you can't change it now with all your mathematics and science. For me that is all there is too it. For you, it seems there is a myriad of mathematics and defined precision that portrait photography simply doesn't have any use for. You can't 'see' a change in the perspective because you don't have the ability to 'see' it. Do you understand that much? You are not able to even comprehend the meaning of what I originally said, much less put your argument into perspective when discussing a portrait. Doug > That was me who put that forward, Jeremy. Perhaps Jeremy, your > interpretation of 'perspective' as applied to photographing portraits is > different to the interpretation of Photographers who actually take portraits > for a living? Portraits are not relevant. There aren't some special laws of physics that come into play depending on what you put in front of your camera. > They know a 100 mm lens will produce a portrait with better 'perspective' > than your assertion that a 20mm one can too. Then they are flat-out wrong. You want to prove it? I can take a picture at 20mm using my point-and-shoot camera that will have the same perspective you're talking about that you insist you can only get with a much longer lens. This is trivial to demonstrate; just try it. And it does not change if you stick a person in front of the camera. I mean, really -- you are insisting that no point-and-shoot digital camera is capable of producing "telephoto perspective". You are insisting that I can zoom in all the way on that point-and-shoot camera and I will still get the wide-angle distortion I'd get using a wide-angle lens on an SLR, simply because the optical focal length is short. This is just not the case. Do you really think that the 7-28mm lens on my point-and-shoot camera will give you the same "distortion" that you'd get using a 28mm lens on a 35mm camera to shoot a portrait? > Technocrats are digital deviates. They embrace photography for it's > technology as much as it's picture taking ability. The statements you made > above, very clearly demonstrate you have little of the artist in you and a > lot of the technologist. I am sorry I can't refute this, since I have no pictures online for you to see. > I still use a portrait lens for portraits because 80, 100 mm focal length > lenses produce a better perspective to the photograph. That is my statement. Your statement is simply not correct. Your 80 or 100mm lenses are "portrait lenses" only assuming a certain sensor size (whether the "sensor" is digital or a piece of film). Your 80mm lens would not be a "portrait" lens on a 4x5 view camera. Have you ever used a 4x5 camera? I have, and though I don't claim that I was ever any good with it, it is a very good demonstration that "80mm lens" doesn't mean *anything* with regard to field of view or perspective, a lesson we learned back before there even were digital cameras. And, yes, when I say I wasn't any good with 4x5, I don't mean technically. I made pictures that were sharp, in focus, perfectly exposed, perspective corrected, film processed according to exposure intent. They just sucked anyway. I do know the difference, I just can't prove it to you, so, whatever. > I learned it from masters of photography, probably before you were born > and you can't change it now with all your mathematics and science. Maybe you learned it from masters of photography before I was born, which is fine, but you learned the wrong thing. "80mm or 100mm" does not mean "portrait lens". "The field of view you get from an 80mm or 100mm lens when used on a 35mm camera" does. Go do some portraits with an 80mm lens on a 4x5, or even better, 8x10 camera, and see how the perspective works out for you. SignatureJeremy | jeremy@exit109.com > Maybe you learned it from masters of photography before I was born, which > is fine, but you learned the wrong thing. "80mm or 100mm" does not mean [quoted text clipped - 5 lines] > -- > Jeremy | jeremy@exit109.com Somehow Jeremy, you seem to have taken from mine and the OP's posts only what suits you and then distorted the perspective of the posts to suit your own entertainment. This is a DSLR group so the inference without needing emphasis is that lens lengths spoken of are in that category. Now you are seeking to introduce bellows cameras into the discussion as if they will somehow fortify your argument... They won't. The original post I made which started all this crap from you and a few other tech-heads which is only of interest to tech-heads anyway ...referred to the OPs camera and the problems associated with blind assumptions of crop factors becoming telephoto factors and depth of field differences when this is done, in case you forgot or more likely conveniently put it aside. I just happened to mention I liked the perspective of the 100 mm lens better than that from a 50mm lens and you still can't grasp what I was talking about. Given the number of post you've made about the mechanics of lenses since then, you probably never will. Maybe it's just as well you gve up on bellows cameras. Doug > Now you are seeking to introduce bellows cameras into the discussion as if > they will somehow fortify your argument... They won't. Will a 80mm lens give the same results on a view camera as on an SLR? If not, why not? If not, why would it give the same results on a "full frame" 24x36 digital SLR as it will on an SLR with an APS-size sensor? > The original post I made which started all this crap from you and a few > other tech-heads which is only of interest to tech-heads anyway ...referred > to the OPs camera and the problems associated with blind assumptions of > crop factors becoming telephoto factors and depth of field differences when > this is done, in case you forgot or more likely conveniently put it aside. You're the one who keeps claiming that focal length determines perspective, which is just flat-out wrong, and can trivially be proven wrong. > I just happened to mention I liked the perspective of the 100 mm lens better > than that from a 50mm lens and you still can't grasp what I was talking > about. That's because the statement is meaningless without also specifying the size of the sensor you're using, since "100mm" and "50mm" don't imply anything about the field of view of the lens. What you really mean is that you like the perspective you get when you use a 100mm lens on a 35mm camera from portrait distance. This doesn't say much about what you'll get with a 100mm lens at portrait distance with an APS-size sensor. SignatureJeremy | jeremy@exit109.com > What you really mean is that you like the perspective you get when you use > a 100mm lens on a 35mm camera from portrait distance. This doesn't say [quoted text clipped - 3 lines] > -- > Jeremy | jeremy@exit109.com You get the same depth of field Jeremy. And that is precisely what I started with... Originally I said something along the lines that a wide held belief that 1.6 crop factor was in fact a telephoto factor, was wrong and went on to explain why it was so. You saw fit to take one part of what I said (about the perspective of a portrait being lost in that presumption) and make your own entertainment out of it. I really don't care too much if you are a Rhodes scholar in optical engineering... You really need to take into consideration the thread which you hijack before you get your rocks off on people who are not engineers. I post here as a practicing Professional Photographer with 45 years in the trade. Yes, when I was apprenticed as a Photographer it was a trade. You seem to think my training and those before me (many of whom are well respected and published authorities on the subject) who actually have a grasp on the perspective of a portrait should all now bow to the engineers statement that perspective is an engineering term and it is not to be tied to focal length. Somehow the ditty of how many Engineers are needed to change a light bulb comes to mind here. Doug > "Jeremy Nixon" <jeremy@exit109.com> wrote in message > [quoted text clipped - 4 lines] > > You get the same depth of field Jeremy. No, you don't. Still, depth of field has nothing to do with perspective. > Originally I said something along the lines that a wide held belief that 1.6 > crop factor was in fact a telephoto factor, was wrong and went on to explain > why it was so. But it is, in every way that actually matters, and the explanations you have offered have amounted to nothing more than "I've been a photographer since before your great-grandfather was born and I say so". Oh yeah, plus the whole "magic perspective" thing you get when shooting a portrait that doesn't happen with any other subject. > You really need to take into consideration the thread which you hijack > before you get your rocks off on people who are not engineers. But *I'm* not an engineer. SignatureJeremy | jeremy@exit109.com > I made the mistake of presuming this group was frequented by photographers > and artistic people who had natural perspective appreciation as part of [quoted text clipped - 5 lines] > produce a portrait with better 'perspective' than your assertion that a 20mm > one can too. Many could make the portrait with or without a camera. Garbage. You've started whining about art and denouncing people who actually have a real appreciation for the means by which an image is formed on film. If you want to pretent that there's a magic portrait land in which perspective is a mysterious and wonderful thing, unaffected by, say, the straight-line nature of light then go ahead. The rest of us are going to sit back and continue concluding that you're an idiot. B > able to even comprehend the meaning of what I originally said, much less put > your argument into perspective when discussing a portrait. The only point that matters Doug, is that perspective is what perspective is, and it is not anything else but what it is. Several people have set out examples for you to follow in order to understand it, in general and in the context of portraits. The exercises Gisle and I, and others proposed would clearly demonstrate the principle if you would try them. Delving into an alternate meaning based on 'portraits', does not make your definition correct in any way. Perspective is a matter of distance from the viewer to the subject. Period. Focal length has nothing to do with it. Period. What you say about lenses around 100mm (35mm frame) being preferred for portraits is true. And it is entirely based on perspective, that is true. Try a full frame of a head/shoulders shot with a 50mm and it is obvious why a longer FL is preferred. Stand back where you shoot the 100 for a full frame head shoulders and shoot with the 50mm. Crop the result. It will have the same perspective and look as the 100mm. You will find that such admission will not change your ability to make portraits, and it might even improve your photography in some other context. Cheers, Alan. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: there's no such thing as a FreeLunch. > > able to even comprehend the meaning of what I originally said, much less put > > your argument into perspective when discussing a portrait. > > The only point that matters Doug, is that perspective is what perspective is, > and it is not anything else but what it is. > You will find that such admission will not change your ability to make > portraits, and it might even improve your photography in some other context. > > Cheers, > Alan I am tempted to continue in the face if contradiction but I fear there is no point in attempting to make the horse drink after getting it to the water. http://209.196.177.41/07/07-06.htm Doug > I am tempted to continue in the face if contradiction but I fear there is > no point in attempting to make the horse drink after getting it to the > water. > http://209.196.177.41/07/07-06.htm Very good Doug. Just showing what I said in a prior post regarding the suitability of, eg: a 50mm used close up on a person. Now, repeating what I and others have said: Take the same wide angle lens and shoot from the same __distance__ away that you would shoot the longer lens to about fill the frame. eg: the wider lens will now show the persons head as a small part of the frame. Do this in the center. (eg: shoot both the 50mm and 100mm from about 2 meters away with the same subject). Shoot. Last: take the 50mm shot to photoshop, crop out the shot of the person so the head fills the frame. Voila... same perspective and look (no figure distortions) as the long lens at that distance. Cheers, Alan. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: there's no such thing as a FreeLunch. "Stand back where you shoot the 100 for a full frame head > shoulders and shoot with the 50mm. Crop the result. It will have the same > perspective and look as the 100mm. I am beginning to grasp to stupidely simple notion that the perspective you techno geeks are on about is the diverging line perspective where there is a vanishing point possibly somewhere out of view. Even this could change with different focal lengths but anyway... This is not the perspective I am talking about. If you can identify the source of the following statement, you might just become a better photographer yourself - Alan. "If you're not trying to fill the frame with the subject's face, you don't actually need a telephoto lens to avoid an unflattering perspective." Doug > "Stand back where you shoot the 100 for a full frame head >> shoulders and shoot with the 50mm. Crop the result. It will have the [quoted text clipped - 11 lines] > "If you're not trying to fill the frame with the subject's face, you don't > actually need a telephoto lens to avoid an unflattering perspective." Stop spinning your wheels Doug. The notion of filling the frame was an exercise for you to understand why a shot of 50mm at dist. x gives the same perspective of a shot taken with a 100mm lens at dist x. Cropping the 50mm shot after the fact will yield an identical image (minus very minor differences in the two lens' distortions). You appear to be in "pride" mode where you can't simply admit that you're wrong about persepective being only, solely and nothing but the distance between the lens and the subject. And yes, this has a much bearing on portraits as landscapes and architectural shots. Cheers, Alan. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: there's no such thing as a FreeLunch. > You appear to be in "pride" mode where you can't simply admit that you're > wrong about persepective being only, solely and nothing but the distance [quoted text clipped - 3 lines] > Cheers, > Alan. Hold on... I never said perspective is "only, solely". What I said was using a Portrait lens of 100mm or thereabouts (to shoot a portrait being the unspoken intent - because that is what I do most of the year) would produce a better perspective than using a wide angle lens. I also said the reason for this was the depth of field didn't change with an implied telephoto crop factor so using a 50 or 75mm lens with a crop factor of 1.6 did not produce the shallow depth of field ("the same perspective") as a 100 mm lens did. Somehow or another you and that other imitation geek Jeremy Nixon can't grasp this photographic phenomenon and instead chose to take only a part of one sentence of what I said and apply it to your "bash Doug's theory" attack that has absolutely nothing to do with the original statement. All this crap about "pride" mode is the way you behave, not me. When was the last time you apologised to anyone? I have no need of justification of my statement to you or any other amateur. If you took the time to consider what I said, you'd have no alternative but to agree with it but like all your other posts in reply to photographic composition issues, you simply don't understand the statement or worse, choose not to. I haven't a clue where you and Jeremy got the notion you were so expert in the field of photography that you could re-write so many quotes from so many eminent professionals in so many accepted references. At least 15 text books and Photographic reference manuals I went through in the willingness to accept maybe what I had learnt in the last 40 years (and has been written about for 400 years) could be wrong... All agree with what I originally said. Like Jeremy, you lost the plot. Sadly your argument simply doesn't relate to the whole statement I made. What I said earlier about diverging lines has absolutely nothing to do with my original statement and everything to do your ability to comprehend. Doug >>You appear to be in "pride" mode where you can't simply admit that you're >>wrong about persepective being only, solely and nothing but the distance [quoted text clipped - 13 lines] > of 1.6 did not produce the shallow depth of field ("the same perspective") > as a 100 mm lens did. I've several times said: -100mm (or around there, 85 - 135 is fine with me) is appropriate for most portraits. -I've also said that the perspective of the CROPPED portion of a shorter focal length gives exactly the same result from THE SAME DISTANCE to the subject as if shot from the more appropraite lens. For simplicity sakes, I used 50mm and 100mm as example lenses and in the context of 35mm camera. -I never made any claim about DOF being equal. I did point out what the DOFs would be for a common CoC. (Dec 20). THAT IS ALL. I, and others, have indicated several ways for YOU to check this out. If you are the professional you claim to be, this should take you no more than a few minutes to try out. So you can go around accusing people of being amateur this, or geek that, but the truth is that perspective is a result of distance not focal length. And that you can't doff your hat and admit so is indicative of your poor spirited mind. And yes, I've admitted my own mistakes here more times than I care to count. Cheers, Alan If you are the professional you claim to be, this > should take you no more than a few minutes to try out. > [quoted text clipped - 6 lines] > Cheers, > Alan Suggesting I lied about my occupation could be construed as a breach of the charter of this group. As I recall, it's on your web site and goes on about personal insults not being acceptable. To suggest I'm a liar ("If you are the Professional you claim to be") because said I own a company, currently in the photographic business and have been a paid photographer since I served my apprentice as a photographer (starting in January 1959 at the StKilda, Melbourne, (Australia) Studios of Campbell & Son Photographers), is tantamount to a personal attack on me. SO now will you delete the stuff on your site so it's OK to stoop to personal attacks? Like you did with the 3 line sig you promoted on the site until I pointed out yours was longer? Naw... You wouldn't do that again, would you? Alan, From your own admission, you are an amateur photographer. Personally I really couldn't see the title of geek fitting you as well as it does Jeremy but none the less the fact that I derive an income from the trade I've been part of for 46 years and you don't, qualifies me to make the statement I did about answering to an amateur. The part I haven't yet figured out about you is where you get a lot of the total rubbish you come out with. It certainly isn't from recognised literature and it most certainly couldn't be from practical experience or you'd have gone broke years ago. Nero found out that shooting the messenger because he didn't like the news, had no impact on the news itself. I can only wonder at your attempt to make me look like I don't know what I said, being in the same catagory. The fact that a good deal of your argument would see you taking portraits with a 18mm lens at 10 feet distance and claiming they actually look like portraits, has not escaped me. Sort of puts the whole thing into perspective now, doesn't it? Really Alan... You could not seriously suggest a portrait will have the same perspective wether it's taken with a 20mm or 120mm lens and keep a straight face? You do know the damage a speedlight can do a person's eyes at close range, don't you? Your suggestion you could do this (and get away with it) fails to take into consideration that even if you did manage to take the picture with a lens 10" away from the subject without getting a sock in the jaw for your trouble, the optical distortion of the image is totally uncorrectable. If you stand back, the resulting image will need to be cropped so severely, it won't enlarge to a portrait. You do know the size of a traditional portrait, I take it? Maybe instead of figuring out how to goad me with your childish inferences, you might take the time to consider the writings of Rembrandt himself on the subject. If that's too heavy, there is plenty written on the subject in Kodak and Ilford publication or more recently, some paperbacks on portraiture you can buy at the local camera stores. I'm sure even Canada has free libraries you can find the writings of some of the old masters of portraits to brush up on. You never know, you might just discover that perspective does not just describe a vanishing point. Unfortunately.. That's all from me for several weeks, (Cheers from everyone!) I'm off on a shoot to Arnhem land on the edge of the Gulf of Carpentaria tomorrow. Followed by a few days in the most beautiful part of Australia I have ever seen: Kakadu National Park. If you are patient, I might just share some portraits of traditional Australians with you... No, not taken with 20mm lenses either! Doug > If you are the professional you claim to be, this > [quoted text clipped - 12 lines] > charter of this group. As I recall, it's on your web site and goes on about > personal insults not being acceptable. I never suggested you lied. I suggested the you behave like a professional and look at what is being said as a professional would. > To suggest I'm a liar ("If you are the Professional you claim to be") > because said I own a company, currently in the photographic business and [quoted text clipped - 9 lines] > but none the less the fact that I derive an income from the trade I've been > part of for 46 years and you don't, qualifies me to make the statement I did I stopped reading right here. You have not answered me or Gisle or anyone on the simple comparison of a cropped image from a wider lens v. a longer lens. Why? Are you afraid to find the truth? I really don't care if you don't understand what 'perspective' means. Bye. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: there's no such thing as a FreeLunch. >I stopped reading right here. You have not answered me or Gisle or >anyone on the simple comparison of a cropped image from a wider lens v. >a longer lens. Why? Are you afraid to find the truth? > >I really don't care if you don't understand what 'perspective' means. Nor do many of the rest of us, and it's getting *really* tiresome seeing the argument go on, and on, and on, and on, and on, ... Just put Mr. "I'm never wrong" in your killfile, and move on. (or if you don't have a killfile, exercise restraint, and ignore him. So that means he gets the last word in the argument. Big deal.) > Just put Mr. "I'm never wrong" in your killfile, and move on. You can do the same with the subject titles. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: there's no such thing as a FreeLunch. > it's getting *really* tiresome > seeing the argument go on, and on, and on, and on, and on, ... > > Just put Mr. "I'm never wrong" in your killfile, and move on. > (or if you don't have a killfile, exercise restraint, and ignore him. > So that means he gets the last word in the argument. Big deal.) With respect, some of us find the topic not only interesting, but fundamental to the practising of photography. If you personally don't find it of interest, just don't read the thread. No thread interests everyone in the NG. If you really want to complain about a long-running thread, have a go at the 'Horrendous Tsunami Pics' thread - not only is it much bigger than this thread, it's gone off the original topic into Iraq etc. - nothing to do with tsunamis. Colin >> it's getting *really* tiresome >> seeing the argument go on, and on, and on, and on, and on, ... [quoted text clipped - 5 lines] >With respect, some of us find the topic not only interesting, but >fundamental to the practising of photography. Quite. But that part of it was covered, repeatedly, in the first few postings to the thread. By now, there's nothing new being said that wasn't covered in the first postings (let's say the first 100). So we're what, 20 levels deep in the tree, with nothing but repeated "I'm right" "No, you're wrong" "No, I'm right" bickering. That really isn't adding anything new to the discussion of the topic, nor is it saying anything fundamental about the practice of photography. Note, too, that I specifically put my comment in one branch of the tree; there are a couple of other branches with a better signal-to-noise ratio. That's where any interesting points might be raised; points that would be missed if I followed the suggestion to simply kill the whole thread. >>> it's getting *really* tiresome >>> seeing the argument go on, and on, and on, and on, and on, ... [quoted text clipped - 13 lines] > That really isn't adding anything new to the discussion of the topic, > nor is it saying anything fundamental about the practice of photography. Apparently he's gone now, so maybe we can let this subthread wither and die? > Note, too, that I specifically put my comment in one branch of the tree; > there are a couple of other branches with a better signal-to-noise ratio. > That's where any interesting points might be raised; points that would > be missed if I followed the suggestion to simply kill the whole thread. Glad to observe that note! Will D. >>I stopped reading right here. You have not answered me or Gisle or >>anyone on the simple comparison of a cropped image from a wider lens v. [quoted text clipped - 8 lines] > (or if you don't have a killfile, exercise restraint, and ignore him. > So that means he gets the last word in the argument. Big deal.) Only problem with killfiling is that all the responses continue to be seen. Anything more drastic gets rid of stuff that might be of value. Restraint is an option, but so is abuse and exploitation, depending on whim of the moment, I guess. Will D. > Alan, From your own admission, you are an amateur photographer. In photography (unlike some other fields), being a professional qualifies you to better comment on the business of photography, but not really the art or the craft. Many amateurs are better at this than many pros. So continually insisting that you're right because you're a professional really doesn't work. > Really Alan... You could not seriously suggest a portrait will have the same > perspective wether it's taken with a 20mm or 120mm lens and keep a straight > face? If the 20mm is used on a camera with a very small sensor, yes, he could seriously suggest that. In case you've never used a camera with a sensor smaller than 24x36mm, that means you *wouldn't* be ten inches away from the subject's face to fill the frame properly. You'd be back at normal portrait distance. I don't necessarily suggest that this is a good way to make top-quality portraits, but the reasons why it's not have nothing to do with perspective. SignatureJeremy | jeremy@exit109.com >In photography (unlike some other fields), being a professional qualifies >you to better comment on the business of photography, but not really the >art or the craft. Many amateurs are better at this than many pros. So >continually insisting that you're right because you're a professional >really doesn't work. People who use their trade experience as the main proof for technical arguments usually have no argument. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< > Really Alan... You could not seriously suggest a portrait will have the same > perspective wether it's taken with a 20mm or 120mm lens and keep a straight > face? You do know the damage a speedlight can do a person's eyes at close At a given distance away, and centered in the lens, yes indeed. Of course, the subject will be mighty small in the 20mm version. For perspective is a fucntion of seeing an object at a distance. It is independant of the field of view of the lens. A strobe light at a given distance to the subject will give the same output regardless of focal length (ISO and aperture being the same). The exposure will be the same. It is clear that you're not reading what everyone has been saying to you: regardless of the focal length, take the shot at a given distance and then crop the results of the wider lenses. Blow that cropped version up, and it will be the same as the longer lens. > range, don't you? Your suggestion you could do this (and get away with it) > fails to take into consideration that even if you did manage to take the [quoted text clipped - 3 lines] > cropped so severely, it won't enlarge to a portrait. You do know the size of > a traditional portrait, I take it? This whole discussion in both threads has been about cropping and perspective. Not about what is a portrait focal length. I mentioned only 50mm and 100mm. I've stated many times that the usual lens is in the 85 - 135mm range for portraits (on a 35mm camera). I've never suggested that the 50mm be used as a portrait lens except as an exercise in demostrating perspective to you. You're probably not reading with a view to understanding what I and others have been trying to convey to you. Here it is in the simplest recipe: 1) Take a 100mm lens and compose a portrait of somebody. Make it a nice tight head and shoulders shot. Take the photo. 2) Leave everything alone. Replace the lens with a 50mm lens. Of course the subject looks smaller in the viewfinder now. That's okay take the shot. 3) In photshop, crop the 50mm version to be the same composition as the 100mm version. Print them the same size. No difference. For the same aperture, the DOF will be deeper on the 50mm version. Perspective is the same. You might discern minor differences in distortion. Even you can follow those three simple steps. Can this be done at 20mm? Yes. Caveats are the huge DOF, and the distortion of the lens will probably be noticeable. If it is done very carefully, with the camera back absolutely vertical and square to the subject, and centered, then maybe not as noticeable. The grain and noise will pop out in the cropped image, to be sure. Cheers, Alan. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: there's no such thing as a FreeLunch. > What I said was using a Portrait lens of 100mm or thereabouts (to shoot a > portrait being the unspoken intent - because that is what I do most of the [quoted text clipped - 3 lines] > of 1.6 did not produce the shallow depth of field ("the same perspective") > as a 100 mm lens did. Therein lies the problem, which I now believe I fully understand. You are defining "perspective" as "depth of field", but no one else is. SignatureJeremy | jeremy@exit109.com > > What I said was using a Portrait lens of 100mm or thereabouts (to shoot a > > portrait being the unspoken intent - because that is what I do most of the [quoted text clipped - 9 lines] > -- > Jeremy | jeremy@exit109.com You are getting closer Jeremy but a long way to go yet. I'll give you 9 points for at least trying to comprehend. Doug > "Jeremy Nixon" <jeremy@exit109.com> wrote in message > [quoted text clipped - 3 lines] > You are getting closer Jeremy but a long way to go yet. > I'll give you 9 points for at least trying to comprehend. Hooray for me. But it still doesn't mean that perspective has anything to do with depth of field. SignatureJeremy | jeremy@exit109.com |
Enable EMail Alerts
Start New Thread
Reply to this Message