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Photo Forum / Film Photography / 35 mm / February 2005Lens Magnification Question
I'm looking at the following specs of two Canon lenses and can't easily determine which lens will give me the largest magnification for macro type work (I realize a macro lens would be better). So - if I'm shooting a mantis which would yield the largest mantis head in print using a EOS 10D? They both are around 1:5 ratio but does minimum focus distance factor in? Canon Zoom Telephoto EF 100-300mm f/4.5-5.6 USM Autofocus Lens Filter Size 58mm f/Stop Range 4.5-32 / 5.6-38 Minimum Focus Distance 4.9' Magnification 1:5 Zoom/Focus Control 2 Touch Angle of View 24 to 8 Degrees Groups/Elements 10/13 Length 4.8" Maximum Diameter 2.9" Weight 1.18 lb Canon Zoom Wide Angle-Telephoto EF 28-135mm f/3.5-5.6 IS Image Stabilizer USM Autofocus Lens Filter Size 72mm f/Stop Range 3.5-22 (5.6-36) Minimum Focus Distance 1.64' Magnification 1:5.26 Zoom/Focus Control Two-touch (twist) Angle of View 76 to 18 Degrees Groups/Elements 12/16 Length 3.8" Maximum Diameter 3.1" Weight 1.1 lb > I'm looking at the following specs of two Canon lenses and can't easily > determine which lens will give me the largest magnification for macro type [quoted text clipped - 7 lines] > Canon Zoom Wide Angle-Telephoto EF 28-135mm f/3.5-5.6 IS Image Stabilizer > Magnification 1:5.26... Both would yield an image with the same magnification. However, the 100-300 lens would give you a "candid" portait where the 28-135 would give the "paparazzi" shot (the closer minimum distance might frighten or shade the subject). -Dave Thanks for the response Dave. I like the way you explained the impact on focusing distance (paparazzi / candid). Got a chuckle out of me. >> Canon Zoom Telephoto EF 100-300mm f/4.5-5.6 USM Autofocus Lens >> Magnification 1:5... [quoted text clipped - 8 lines] > > -Dave > I'm looking at the following specs of two Canon lenses and can't easily > determine which lens will give me the largest magnification for macro type > work (I realize a macro lens would be better). So - if I'm shooting a > mantis which would yield the largest mantis head in print using a EOS 10D? > They both are around 1:5 ratio but does minimum focus distance factor in? The 28-135 would be better for closeups simply due to the Min focus distance. With a magnification of 1:5.26 the image of the mantis head, when focused at closest appraoc (and I assume longest FL), 5.26 times smaller on the film (or sensor) than the real life object. For example, if the mantis head is 5.26 mm across, then the image formed on the film (or sensor) will be 1mm across (at closest focus and presumably 128mm). That will not reveal great detail. On a Canon 20D, 1mm is 156 pixels. I hope that helps. Cheers, Alan. > Canon Zoom Telephoto EF 100-300mm f/4.5-5.6 USM Autofocus Lens > Filter Size 58mm [quoted text clipped - 20 lines] > Maximum Diameter 3.1" > Weight 1.1 lb  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. Thanks Alan. Based on the numbers it would appear that the 1.5 would yeild a larger subject that the 1.526 magnification. Unless I'm interpreting the data wrong. Strange thing - I had an opportunity to evaluate both lenses (I already own the 28-135 but was wondering if the 100-300 would give me larger subjects). Would you believe the 28-135 produced a larger subject from the lenses minimum focusing distance? That just doesn't make sense to me based on the Canon specifications for magnification. There is a later post in this thread from Dr. Joel Hoffman that used a different formula than the published magification spec. It seems his method gets the correct results but I don't understand why the Canon magnification specs. don't match. 1:5 should produce an image that is slightly larger than 1:5.26 > The 28-135 would be better for closeups simply due to the Min focus > distance. > > With a magnification of 1:5.26 the image of the mantis head, when > focused at closest appraoc (and I assume longest FL), 5.26 times > smaller on the film (or sensor) than the real life object. > For example, if the mantis head is 5.26 mm across, then the image > formed on the film (or sensor) will be 1mm across (at closest focus > and presumably 128mm). > [quoted text clipped - 4 lines] > Cheers, > Alan. > Thanks Alan. > > Based on the numbers it would appear that the 1.5 would > yeild a larger subject that the 1.526 magnification. > Unless I'm interpreting the data wrong. I think you're missing one point. Regarding the 28-135mm with a min foc dist of 1.64': Put the lens on a film camera and on a 20D. The 5.6 mm mantis head will render: as 1mm on the digital sensor and it will render as 1mm on the film in the film camera. 1mm in both cases. IOW: The crop factor HAS NO EFFECT ON THE SUBJECT SIZE AT THE SENSOR OR FILM. The image frame is cropped, that's all. The focal length of the lens is not changed. As film is 24x36mm and the 20D is 22.5 x 15mm, the _proportion_ of the mantis head to the entire image is larger on the 20D, but the actual image is the exact same size on both. And the film image will contain more of the scene (and body of the mantis as it is not cropped. I hope that is clearer now. > Strange thing - I had an opportunity to evaluate both > lenses (I already own the 28-135 but was wondering if [quoted text clipped - 12 lines] > 1:5 should produce an image that is slightly larger > than 1:5.26 Only at the same FL, at min foc. dist up to the point where both lenses see an object in focus at the same FL. (eg: both lenses at 100mm, the 28-135 will get a bigger reprod than the other up to 4.9 ft. After that they should both be the same for the same FL and focus dist). 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. Thanks for taking the time to reply again. Maybe I didn't explain myself very well. I know how crop factors work. I understand what you are saying regarding film vs digital sensors (crop factor) and lens performance. I also understand and agree with the math you presented (5.6mm should be 5.26mm) regarding the head size based on the magnification spec. My question is different. I'm not concerned with the differences between film and digital sensors (effects of crop factor). I'm concerned with the differences in magnification specification between the two lenses. The 100-300mm has the spec of 1:5, the 28-135 has the spec of 1:5.26 - based on those numbers it would appear that the 100-300 should produce a larger subject - yes? It's interesting to me because I had a chance to evaluate both lenses together the 28-135 produced a much larger subject than the 100- 300. I know I should be using a macro, extention tube, close up lens etc. etc. but I'm trying to learn more about lenses (and their specs). Why does a lens with a magnification spec. of 1:5.26 produce a subject larger than one with a mag spec of 1:5? Maybe I should forget about the mag spec and use Dr. Hoffmans formula since it appears coincide with the results I saw. Thanks again for the time you spent replying and trying to help me figure this thing out! >> Thanks Alan. >> [quoted text clipped - 21 lines] > > I hope that is clearer now. If you are seriously interested in mantis heads (?), then I would venture to suggest that you are wasting your time with a 1:5 `macro` (it's NOT macro at 1:5, no matter what the lens maker claims!), and that you will be seriously disappointed. Think *real* macro lens (like the Tamron 90, or the Canon 100), extension tubes, or close-up add-on lenses - in that order for quality. Hmm, *can* you use extension tubes on a 10D? I would presume and hope so.. >If you are seriously interested in mantis heads (?), then I would >venture to suggest that you are wasting your time with a 1:5 `macro` [quoted text clipped - 5 lines] >Hmm, *can* you use extension tubes on a 10D? I would presume and hope >so.. Yes. SignatureDavid Littlewood I agree. But I really just wanted to compare the two lenses and gain an understanding of what the magnification specification Canon supplies really means. chrlz@go.com wrote in news:1109317905.946854.68230 @o13g2000cwo.googlegroups.com: > If you are seriously interested in mantis heads (?), then I would > venture to suggest that you are wasting your time with a 1:5 `macro` [quoted text clipped - 5 lines] > Hmm, *can* you use extension tubes on a 10D? I would presume and hope > so.. > If you are seriously interested in mantis heads (?), then I would > venture to suggest that you are wasting your time with a 1:5 `macro` [quoted text clipped - 5 lines] > Hmm, *can* you use extension tubes on a 10D? I would presume > and hope so.. Unless you are going to do a lot of this, you could think about using a _good_ two element add-on closeup lens. The Achromatic two element ones don't degrade the image much, you don't lose effective lens speed as you do with tubes or other sorts of extension, and they also work a lot better with zooms than adding extension does. (Add extension to a zoom and it will no longer remain in focus as you zoom, which sort of removes the usefulness of it being a zoom in the firt place, in the closeup context.) I like the Nikon two element dioptres: I gather the Canon ones are OK too. Otherwise, yes, I'd use a macro lens, or a _real_ macro zoom (like the Vivitar Series 1 90-180, but that's no longer made and probably never was in EOS mount), or extension with a fixed FL lens. Peter Thanks Peter... I was considering getting an extention tube set (to start me off) but I will look into two element close up lenes at the same time. >> If you are seriously interested in mantis heads (?), then I would >> venture to suggest that you are wasting your time with a 1:5 `macro` [quoted text clipped - 24 lines] > > Peter > If you are seriously interested in mantis heads (?), then I would > venture to suggest that you are wasting your time with a 1:5 `macro` [quoted text clipped - 5 lines] > Hmm, *can* you use extension tubes on a 10D? I would presume and hope > so.. extension tubes are an optical feature what kind of medium you use to cature it is not particularily relevant. SignatureSander +++ Out of cheese error +++ >I'm looking at the following specs of two Canon lenses and can't easily >determine which lens will give me the largest magnification for macro type [quoted text clipped - 26 lines] >Maximum Diameter 3.1" >Weight 1.1 lb It can be difficult to calculate the reproduction ratio (magnification) of modern lenses as the focal length sometimes changes on close focussing. The only reliable way is to test it, or use the manufacturer's own figures. From the Canon book "EF Lens Work III" (a very useful reference for any Canon user): EF 28-135 f/3.5-5.6 IS USM Maximum magnification 0.19x EF 100-300 f/4.5-5.6 USM Maximum magnification 0.20x The difference is not significant. I have both lenses (or used to have, the 100-300 met a sad fate in a rock pool). Neither are very good for macro work, but can serve. You will need an auxiliary close-up lens to get anything worthwhile with a small insect. Your best bet for the kind of work you describe would emphatically be to get a proper macro lens, as others have said. If you are determined to get one of the above two, the 28-135 is a much better lens for general purpose photography (especially on a 10D, with its 1.6x crop factor). The 100-300, in my experience, vignettes rather too much to be acceptable. David SignatureDavid Littlewood >> I'm looking at the following specs of two Canon lenses and can't easily >> determine which lens will give me the largest magnification for macro [quoted text clipped - 38 lines] > > EF 28-135 f/3.5-5.6 IS USM Maximum magnification 0.19x That's what the 1:5.26 above refers to... > EF 100-300 f/4.5-5.6 USM Maximum magnification 0.20x That's what the 1:5 above refers to... 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. Thanks David. I currently own the 28-135mm lens and love it. I wanted to add an inexpensive zoom telephoto and wondered how the 100-300mm would impact my ability to shoot macros since it's magnification 'appeared' to slightly more than the 28-135. Strangely, the 28-135 outperformed the 100-300 in magnification when I had a chance to compare earlier today (Not to mention the 28-135 had IS on top of more magnificaiton). From the book you referenced I get a similar relationship to the published Canon specification (i.e the 100-300 appears to provide more magnification). But in reality thats no what I experienced today. Thats very confusing to me. I agree a macro would be best. But I wanted to understand the specs and how they relate to the lens performance. P.S. Sorry to hear about the fate of your 100-300 :( > It can be difficult to calculate the reproduction ratio > (magnification) of modern lenses as the focal length sometimes changes [quoted text clipped - 23 lines] > > David >Thanks David. > [quoted text clipped - 14 lines] > >P.S. Sorry to hear about the fate of your 100-300 :( My daughter did it in the Galapagos. I still love her though - I had already replaced it with a 100-400 L IS and had handed it to her on "loan". PS - If you choose to use extension tubes, the 28-135 show a bigger jump in magnification than the 100-300. Also, the IS on the 28-135 will still work on the 28-135 with a close-up lens (but possibly not with an extension tube, depending on details). PPS - Pretty well any fixed focal length lens of moderate specification (i.e. I exclude 14mm wides and the like) will be better with extension tubes than a zoom. David SignatureDavid Littlewood >I'm looking at the following specs of two Canon lenses and can't easily >determine which lens will give me the largest magnification for macro type >work (I realize a macro lens would be better). So - if I'm shooting a >mantis which would yield the largest mantis head in print using a EOS 10D? >They both are around 1:5 ratio but does minimum focus distance factor in? Yes, the minimus focus distance factors in. And so does the zoom length (100mm, 300mm, 35mm, etc.) The 1:5 ratio is completely irrelevant for magnification. At the same zoom length, the lens with the closer focusing will give you more magnification. At double the zoom length, if you are more than twice as close you'll get more magnification. Look at it this way: zoom-length / distance = magnification So the 300mm zoom at 5' will give you a little less mangification than the 135mm zoom at 1.64'. Also bear in mind that the longer zoom will be harder to use, because you'll need higher shutter speeds to combat blur. And the IS on the 35-135 will be invaluable if you're not using a tripod. So of the two, go for the 35-135 IS. It's a great lens. But if you really want close-ups of bugs, get a macro lens. -Joel ---------------------------------------------------------------------------- Please feed the 35mm lens/digicam databases: http://www.exc.com/photography ---------------------------------------------------------------------------- Dr. Hoffman: In practice your calculation proved to be correct. I had a chance to evaluate both side by side and to my surprise the 28-135 did in fact produce a larger subject than the 100-300. The equation you supplied makes good sense but why does Canon provide magnification specifications that don't line up with the results? 100-300mm 1.5 mag <-- resulting subject should be larger correct? 28-135mm 1.526 mag Thanks for your response. > Yes, the minimus focus distance factors in. And so does the zoom > length (100mm, 300mm, 35mm, etc.) The 1:5 ratio is completely [quoted text clipped - 27 lines] > ----------------------------------------------------------------------- > ----- >In practice your calculation proved to be correct. I had a chance to >evaluate both side by side and to my surprise the 28-135 did in fact >produce a larger subject than the 100-300. The equation you supplied >makes good sense but why does Canon provide magnification specifications >that don't line up with the results? I can only think of two reasons the Canon magnification specs don't match up with your results: 1. The specs refer to magnification at some other focus distance than the minimum distance. 2. The specs are wrong. -Joel Thanks for the direct and to the point response! I think thats pretty much the same conclusion I've come to? :) Take care, Von joel@exc.com (Dr. Joel M. Hoffman) wrote in news:D0qUd.5241$Gy2.5181 @fe12.lga: >>In practice your calculation proved to be correct. I had a chance to >>evaluate both side by side and to my surprise the 28-135 did in fact [quoted text clipped - 11 lines] > > -Joel |
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