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Photo Forum / Film Photography / Large Format / October 2004Roll film back and focal length
Sorry if this question has been asked many times: If I put a roll film back (6x7 or 6x9) on a 4x5 camera, will this change the effective focal length of the lens? By how much? I want to be able to control perspectiv by shifting, and have read that a rollfilm adapter on a 4x5 camera makes a cheaper and more versatile solution than MF camera with (rare and expensive) shift lenses. However with 1,5 or 2x as long effective focal lenghts of the lenses, this advantage would partly be lost again, right? Thanks for answers... Bernhard > Sorry if this question has been asked many times: If I put a roll film back > (6x7 or 6x9) on a 4x5 camera, will this change the effective focal length of [quoted text clipped - 9 lines] > > Bernhard A 150mm lens is a 150 on any format. On 4x5 a 150 is a normal lens on roll film it is a short tele lens.  SignatureTo reply no_ HPMarketing Corp. > Sorry if this question has been asked many times: If I put a roll film > back (6x7 or 6x9) on a 4x5 camera, will this change the effective focal > length of the lens? By how much? You have been led astray. If you are using a 4x5 and place a rollfilm back on it, nothing changes but the size of the film. > You have been led astray. If you are using a 4x5 and place a rollfilm > back on it, nothing changes but the size of the film. Hmm - but the other poster suggested that for example 150mm with a rollfilm back on a 4x5 behaves like a light tele (actually as a focal lens multiplier), and as normal on 4x5 sheet film. So If I use a lets say 90mm lens ( isn't this wide angle for LF?) with my roll film back, wont it behave like almost a normal lens? regards, Bernie >Hmm - but the other poster suggested that for example 150mm with a rollfilm >back on a 4x5 behaves like a light tele (actually as a focal lens >multiplier), and as normal on 4x5 sheet film. So If I use a lets say 90mm >lens ( isn't this wide angle for LF?) with my roll film back, wont it behave >like almost a normal lens? You and the other poster are right. While a lens will not alter its focal length when you change film formats, the angle of view most certainly will, and a 150mm lens, normal to wide-anglish for 4x5, will yield a much narrower view on the smaller, medium format negative. The view obtained on a Pentax 6x7 with the 75mm shift lens would have to be duplicated on your 4x5 fitted with a 6x7 rollfilm back by another 75mm lens, such as a Super Angulon. One important factor you may not be considering is whether a lens is designed and manufactured to cover 4x5 or medium format, or even 35mm. The wider the film coverage needed, the more the ultimate performance of a lens might be compromised. Thus, generally speaking, you will get better results on MF with a lens designed for it than with one designed for 4x5. So, if you plan to make huge enlargements, chances are you'll be better off with the MF lenses. Bob G > The wider the film coverage needed, the more the ultimate performance of a > lens [quoted text clipped - 4 lines] > to make huge enlargements, chances are you'll be better off with the MF > lenses. Typo, Bob? If huge enlargements are the goal, then using the correct lens on a 4x5 is better when the viewing distance is considered. >> The wider the film coverage needed, the more the ultimate performance of a >> lens [quoted text clipped - 7 lines] >Typo, Bob? If huge enlargements are the goal, then using the correct lens on >a 4x5 is better when the viewing distance is considered. I definitely think that an enlargement from 4x5 will be better than one from medium format, of course. But the whole discussion has been about shooting medium with large format lenses. Again, I believe that an enlargement made on medium format from a lens designed for medium format will likely be better than one from a medium format negative made with a large format lens. Bob G > But the whole discussion has been about shooting medium with large format > lenses. Ah, yes. > Again, I believe that an enlargement made on medium format from a lens > designed > for medium format will likely be better than one from a medium format > negative > made with a large format lens. Probably true. Sorry for taking the thread to a tangent. Quoth bobjames27@aol.com (Bob G): ... | But the whole discussion has been about shooting medium with large format | lenses. | | Again, I believe that an enlargement made on medium format from a lens designed | for medium format will likely be better than one from a medium format negative | made with a large format lens. Do you think this difference would be of a larger order than the typical range of variation between different examples of the same lens? I don't, but then I'm skeptical about the whole issue. Donn >| Again, I believe that an enlargement made on medium format from a lens >designed [quoted text clipped - 5 lines] >typical range of variation between different examples of the same >lens? I don't, but then I'm skeptical about the whole issue. It's hard to tell because there are so many factors at play, only one of them, of course, being the quality of the lens. But if you were to pit the best quality LF lens against a top quality MF lens, both at their best apertures and their best lens-to-subject distance, and at their best this-and-that, both on the same roll of film, I still suspect the MF lens would come out on top. Bob G > But if you were to pit the best quality LF lens against a top quality MF > lens, > both at their best apertures and their best lens-to-subject distance, and at > their best this-and-that, both on the same roll of film, I still suspect the > MF > lens would come out on top. In this type of test in ColorPhoto magazine in Germany exactly the opposite was found. SignatureTo reply no_ HPMarketing Corp. >In this type of test in ColorPhoto magazine in Germany exactly the >opposite was found. Curious. Do you have a URL? Bob G > >In this type of test in ColorPhoto magazine in Germany exactly the > >opposite was found. > > Curious. Do you have a URL? > > Bob G No I have a copy of the magazine but it is in German. SignatureTo reply no_ HPMarketing Corp. Quoth bobjames27@aol.com (Bob G): [quoting me] |> Do you think this difference would be of a larger order than the |> typical range of variation between different examples of the same |> lens? I don't, but then I'm skeptical about the whole issue. | It's hard to tell because there are so many factors at play, only one of them, | of course, being the quality of the lens. [quoted text clipped - 3 lines] | their best this-and-that, both on the same roll of film, I still suspect the MF | lens would come out on top. In case I wasn't clear, I'm saying if you took five of each, there'd be more difference among the five than between the average of each group. Would there actually be a difference between the group averages? For those of us who don't painstakingly test a batch of lenses before buying, it's academic. Donn > For >those of us who don't painstakingly test a batch of lenses before buying, >it's academic. Actually I have done alot of bench testing of store purchased lenses. Generally speaking, They all perform about the same for each class of lens. Example, just about all 5.6 large format lenses perform about the same at f-11 in noon summer sunlight high contrast. Aerial image resolutions will dance around 180 lp/mm. System resolution with this type of lens would be about 32 lp/mm using a 200 asa film and standard film holders. A typical 1.4 35mm format lens will do about 500 l/mm at f-4 in noon summer sun. This will result in system resolution of about 64 l/mm using 200 asa film. System resolutions take in the factors of camera shake, focus errors, day temps, target contrasts, processing chemistry and so on. Larry > Actually I have done alot of bench testing of store purchased lenses. That is great but the majority of the lenses you probably tested were not designed to work as copy lenses of flat field items or for macro shooting. Now you state that "most 5.6 lenses perform about the same at f11" Most large format 5.6 lenses are designed to perform best at f22. Digital view camera lenses and ultra wide lenses like the Apo Rodagon are designed to perform best at f11. "System resolutions take in the factors of camera shake, focus errors, day temps, target contrasts, processing chemistry and so on." To these you have to add processing time variations, chemistry variations in time or temp or strength, atmospheric conditions like dust, emulsion variations from batch to batch. These variations make your type of testing unacceptable for camera and lens manufacturers thus MTF testing was developed to eliminate the variables. SignatureTo reply no_ HPMarketing Corp. >> Actually I have done alot of bench testing of store purchased lenses. >[...] > These variations make your type of testing unacceptable for camera and > lens manufacturers thus MTF testing was developed to eliminate the > variables. Now that we have the elite of LF cameras in the same thread, let me ask: Aerial photography lenses are test wide-open, and theoretically the wider the aperture the sharper an image can be. So, are aerial-photography specific lenses sharper wide open or not? > >> Actually I have done alot of bench testing of store purchased lenses. > >[...] [quoted text clipped - 6 lines] > the aperture the sharper an image can be. So, are aerial-photography > specific lenses sharper wide open or not? I am not sure what lenses you are talking about. The AeroTechnika and Aerotronica lenses were not used primarily wide open. As a former RecTec photographer in the air force whose unit shot Cuba during the missile crises with RF 101 Voodoos as well as the integration at the Universities of Alabama and Mississippi after Cuba I can not remember film that was shot wide open being used. SignatureTo reply no_ HPMarketing Corp. >> Now that we have the elite of LF cameras in the same thread, let me ask: >> Aerial photography lenses are test wide-open, and theoretically the wider [quoted text clipped - 5 lines] > The AeroTechnika and Aerotronica lenses were not used primarily wide > open. I understand that, but the current tests for aerial-mapping lenses are all done wide open, whether the lens has a diaphram or not. > As a former RecTec photographer in the air force whose unit shot Cuba > during the missile crises with RF 101 Voodoos as well as the integration > at the Universities of Alabama and Mississippi after Cuba I can not > remember film that was shot wide open being used. Me: RAF Upper Heyford, 1966-68, 66TRW, "OMNIA CONSPICIMUS", RF-1-1-C Voodo and U2, and believe me, there were lenses shot wide open. I think you have seen one of them on my former web site. But that was a few years after the Cuban Missile Crisis. (What's the integration issue got to do with this? Did you photograph it from the air? :)) Typo: I meant RF-101-C Voodo. :( I flew it often. On the simulator. Saturday mornings, about 1am after the Airmen's club closed after drinking Heinekin at 10-cents a bottle for hours. This was back in the old days before visual sims. All instrument. We used to crank up thunder-storm problems for the special effects. Best contest was putting the Voodo into a ballistic stall, then trying to restart and recover before we made a hole in the ground. I did it. Once. I'm forever spoiled by that big toy. > I understand that, but the current tests for aerial-mapping lenses are all > done wide open, whether the lens has a diaphram or not. Those are lenses for photogramettry which is different then shooting 5" obliques which is what would commonly be shot as aerials by most photographers. > > As a former RecTec photographer in the air force whose unit shot Cuba > > during the missile crises with RF 101 Voodoos as well as the integration [quoted text clipped - 8 lines] > (What's the integration issue got to do with this? Did you photograph it > from the air? :)) Yes we photographed the riots as well as the campuses during the integration process from SC and then from FL. SignatureTo reply no_ HPMarketing Corp. >> I understand that, but the current tests for aerial-mapping lenses are >> all [quoted text clipped - 3 lines] > obliques which is what would commonly be shot as aerials by most > photographers. Good point. > Yes we photographed the riots as well as the campuses during the > integration process from SC and then from FL. From the AIR? I shot the Chicago riots and Days of Rage from right up close and personal. >and U2, and believe me, there were lenses shot wide open. Yes the U-2 search camera was wide open at f-2.8 or was it f-3. I forget now although, I do know several focal lengths were used. The very first cameras had a format of 18 by 18 inches. Two 9 inch camera spools were used to make up this rather large split image. Resolution was rather low but scale was very large due to the large focal length involved. These big "bench box" cameras were discontinued about 1968 or so and replace with a 5 inch search systems. I believe it's all digital now. Larry > >and U2, and believe me, there were lenses shot wide open. > > Yes the U-2 search camera was wide open at f-2.8 or was it f-3. I forget > now > although, I do know several focal lengths were used. Did you see the 3" lens? Frankly, I don't understand why it was there since at 96,000 feet the coverage is the whole earth. Remember how you had to set the quarter window heater preflight? >Did you see the 3" lens? Frankly, I don't understand why it was there since >at 96,000 feet the coverage is the whole earth. That is the 35mm tracker camera. This worked just like the 5 inch wide film search camera. The search camera used a 24 and then a 30 inch lens. Most flights were more like 72,000 ft giving about a 18 inch resolution image on the ground. Not the greatest but it worked time in and time out. Larry >As a former RecTec photographer in the air force whose unit shot Cuba >during the missile crises with RF 101 Voodoos as well as the integration >at the Universities of Alabama and Mississippi after Cuba I can not >remember film that was shot wide open being used. As a rec tech photographer you would know that that combo is rather low system resolution and lucky to do 25 l/mm total system resolution. The saving grace with this system was the rather large focal length lens, the rather large film format, and the super low passes done to get the detail needed. The pictures were such poor quality, the a national aerial photographic office was started called NPIC and the first photographic standards were instituted. Larry >Aerial photography lenses are test wide-open, and theoretically the wider >the aperture the sharper an image can be. So, are aerial-photography >specific lenses sharper wide open or not? This is a good question. First we have to look at a perfect lens. A perfect lens will do about the following center resolutions in noon summer sun. f-stop Resolution f-1 2000 f-2 1000 f-4 500 f-8 250 f-16 125 f-32 64 So a perfect aerial camera lens at f-2 will do about 1000 lines per millmeter wide open. If it's closed down to f-4 it's about 500 lp/mm and at f-16 it's 125. Now a not so perfect lens will do maybe 125 lp/mm at that same f-2 and maybe 500 l/mm at f-4. So it needs to be closed down 2 stops for it sharpest point to be reached where as the aerial lens does not. Larry > Now a not so perfect lens will do maybe 125 lp/mm at that same f-2 and > maybe > 500 l/mm at f-4. So it needs to be closed down 2 stops for it sharpest > point > to be reached where as the aerial lens does not. :) Recognize this 3" lens, Larry? http://course1.winona.edu/jstafford/x/ Maybe I'll look for pictures of the other prototypes and original lenses before machining. >:) Recognize this 3" lens, Larry? Not really. It's a mapper aerial camera lens of some sort. The most important design of this lens is it's low distoration vs it's wide angle rather then just raw resoluton. Larry >That is great but the majority of the lenses you probably tested were >not designed to work as copy lenses of flat field items or for macro >shooting. Well really all kinds of lenses. Generally speaking most did about the same reso in the center. Although you might have a big difference in the type of lens with edge resolution. A copy lens tested at a distance might still have that 500 lp/mm center resolution at f-4 but the edge might do well at just 30 lp/mm. This is vs a field lens that does 500 center and maybe 125 edge. This is vs again a $20,000 aerial camera lens that will do 500 lp/mm all over at f-4. Larry > Hmm - but the other poster suggested that for example 150mm with a > rollfilm back on a 4x5 behaves like a light tele (actually as a focal lens > multiplier), and as normal on 4x5 sheet film. So If I use a lets say 90mm > lens ( isn't this wide angle for LF?) with my roll film back, wont it > behave like almost a normal lens? We had a confusion caused by the way the question was asked, but we are okay now. For all practical purposes, look at it this way: if you require an 80mm lens for your picture as you see it in your medium format (MF) camera, you will need the same focal length if you use a MF back on the 4x5. This issue of the same focal length means that it is unlikely you can use your MF 80mm lens on the 4x5 for a couple reasons. First, the MF lens may not cover a large enough area to permit enough movement, and it's hard to make most LF cameras work with movements with such a short lens because the bellows doesn't move when compressed that much. Bag-bellows can help, but the issue of coverage remains. Silvestri has some _great_ super-wide cameras, but even they allow only flat (rise, fall) control and they also require expensive wide lenses to approach and exceed 80mm. > Sorry if this question has been asked many times: If I put a roll film back > (6x7 or 6x9) on a 4x5 camera, will this change the effective focal length of [quoted text clipped - 6 lines] > Thanks for answers... > Bernhard Think of it as cropping area out of the 4x5, 6x9 per say will not change the focal length, the lens will still focus at the same distance. However you do take a smaller portion of what is seen using a larger film format and more than less you are taking from the central portion of the Ground Glass image, so edge distortion and angle of view are apparently less as well. For instance a 65mm lens will seem wider on 4x5 because there is less film and image area on 6x9. SignatureLF Website @ http://members.verizon.net/~gregoryblank "To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 EXACTLY!!--And well stated!! > > Sorry if this question has been asked many times: If I put a roll film back > > (6x7 or 6x9) on a 4x5 camera, will this change the effective focal length of [quoted text clipped - 14 lines] > For instance a 65mm lens will seem wider on 4x5 because there is less > film and image area on 6x9. > Sorry if this question has been asked many times: If I put a roll film > back (6x7 or 6x9) on a 4x5 camera, will this change the effective [quoted text clipped - 9 lines] > > Bernhard Bernhard - The old rule of thumb is that the diagonal dimension of the film frame is approximately the "normal" focal length. So for 6x6 film, the normal focal length is about 80mm. Therefore, a 150mm lens is moderately long. Likewise, for 4x5 film, the diagonal is 6 inches, or about 150mm, so that same 150mm lens is "normal". So relationship between the focal length of the lens and the film dimensions determines whether the lens is "long", "short" or "normal". That said, if you put a "normal" 80mm lens on a 4x5 camera, and then put a 6x6 roll film back on the same camera, the result is a medium format camera with the ability to move the lens for perspective control. That and the fact that on a per exposure basis, using a roll film back on a 4x5 camera is less expensive than using 4x5 film. Louie > Sorry if this question has been asked many times: If I put > a roll film back (6x7 or 6x9) on a 4x5 camera, will this [quoted text clipped - 11 lines] > > Bernhard The field of view is proportional to the diagonal of the two formats. For instance, the diagonal of 4x5 film is 150mm so the "normal" lens is 150mm. "Normal" for 6x7 is about 100mm so when a 6x7 adaptor is used on a 4x5 camera the FOV is the same as a 225mm lens for 4x5. Obviously, a lens which will cover 4x5 adequately will have loads of margin for a 6x7 image. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com There is a conversion chart on our web site www.viewcamera.com go to the free articles section steve simmons > There is a conversion chart on our web site > [quoted text clipped - 3 lines] > > steve simmons Here is the direct link in case you dont want to see all the advertising. http://www.viewcamera.com/images/focalchart.gif from Jorge Subject: Re: Roll film back and focal length From: rossorabbit@hotmail.com (Jorge Gasteazoro) Date: 10/28/2004 6:47 PM Mountain Daylight Time Message-id: <555a3f23.0410281647.418b5ad7@posting.google.com> largformat@aol.com (Largformat) wrote in message news:<20041027092637.21613.00002840@mb-m10.aol.com>... > There is a conversion chart on our web site > [quoted text clipped - 3 lines] > > steve simmons Here is the direct link in case you dont want to see all the advertising. http://www.viewcamera.com/images/focalchart.gif I gave a direct link to the Free Articles section. There may be other articles as well that would be helpful. Jorge feels the need to perform the self appointed role of censor. It is silly and destructive and limits people's access to information that could be helpful to them. Here is the link to a lot of information that will help people who have an interest in large format photography. www.viewcamera.com steve simmons > Here is the link to a lot of information that will help people who have an > interest in large format photography. > > www.viewcamera.com And here's another one where people actually post information: http://www.largeformatphotography.info/ from ???? Subject: Re: Roll film back and focal length From: "jjs" jj@jj.jj Date: 10/29/2004 12:42 PM Mountain Daylight Time Message-id: <10o53p6o6up5m6c@news.supernews.com> > Here is the link to a lot of information that will help people who have an > interest in large format photography. > > www.viewcamera.com And here's another one where people actually post information: http://www.largeformatphotography.info/>>>>>>>>>>>>>>>>>>>>>>>>>>>> There is actual info on our web site. We get thank you notes all of the time. steve simmons > There is actual info on our web site. We get thank you notes all of the > time. Diversity is good, and in that respect your site adds to it, but the Thank Yous you get are largely ass-kisses. Subject: Re: Roll film back and focal length From: "jjs" jj@jj.jj Date: 10/29/2004 3:48 PM Mountain Daylight Time Message-id: <10o5elslalobcc1@news.supernews.com> > There is actual info on our web site. We get thank you notes all of the > time. Diversity is good, and in that respect your site adds to it, but the Thank Yous you get are largely ass-kisses. Spoken by someone with multiple names - perhaps to avoid kill files ???? steve simmons Diversity is good, and in that respect your site adds to it, but the Thank Yous you get are largely ass-kisses. What really matters is that the people themselves have gotten the help they need. It is their opinion that counts. Your negative b********* is just after the fact is just sour grapes and does nothing for the dialogue. steve simmons > Your negative b********* is just after the fact is just sour grapes and > does > nothing for the dialogue. You know how much I like that kind of talk, so just quit kissing my butt, Steve. >> Your negative b********* is just after the fact is just sour grapes and >> does >> nothing for the dialogue. > >You know how much I like that kind of talk, so just quit kissing my butt, >Steve. What would this NG be without these periodic Stafford-Simmons pissing matches? So much more exciting than restoring an old bellows or focusing rail... Steve, just accept that jjs is the alpha male around these parts. Avoid eye contact and keep your head down when approaching, and nobody gets hurt. rafe b. http://www.terrapinphoto.com > What would this NG be without these periodic > Stafford-Simmons pissing matches? [quoted text clipped - 6 lines] > and keep your head down when approaching, > and nobody gets hurt. Uh huh, I don't know whether to puke or fall asleep. SignatureLF Website @ http://members.verizon.net/~gregoryblank "To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 Now where is your kill file ? I rest my case....only when it suits you. Pathetic. > And here's another one where people actually post information: SignatureLF Website @ http://members.verizon.net/~gregoryblank "To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 > Now where is your kill file ? I rest my case....only when it suits you. > Pathetic. Let's all remember how "Gregory Blank" uses fake identities and how he savaged Simmons to no end and still feels compelled to kiss his a.s. I got a new computer, left the killfile but thanks for the reminder to get it going again, Blank. Yeah John I'll kiss your a.s too, mark off a spot because your all a.s---- and it will be a big fricking X when you do. > Let's all remember how "Gregory Blank" uses fake identities and how he > savaged Simmons to no end and still feels compelled to kiss his a.s. I got a > new computer, left the killfile but thanks for the reminder to get it going > again, Blank. > SignatureLF Website @ http://members.verizon.net/~gregoryblank "To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 > from Jorge > [quoted text clipped - 30 lines] > > steve simmons Nope, I am not censoring anything, just providing information that will prevent you to abuse this site by getting free advertising. I told you I was going to do this. You have been prohibited from doing this at the LF forum and at APUG, why cant you understand that what you do is an abuse. As I said before your site has a few articles that are useful to absolute beguinners, nothing more. If you all want real information, visit APUG, or the LF forum (which BTW do not allow simmons to advertise for free), simmon's rag web site has little info worth having to read the drivel. BTW Simmons, I too get a lot of thank you notes from people I help, but that does not give me the right to announce my print sales here..... |
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