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Photo Forum / Digital Photography / DSLR Cameras / August 2006Canon 18-55 small-format lens
I just bought the old 30D camera (one week before the XTi is announced, and I can't return the thing for free, argh), with the standard zoom lens. (I do love the body, however, so maybe the extra $500 is OK). I've extensively looked at pictures made by the 18-55 zoom, and it appears to be a perfectly ordinary commercial zoom lens. That is, it's crap compared to a 50mm f 1.8 non-zoom, or my 270mm apo-Symmar, especially at the wide end. But with the digital body rather than 50 speed Fuji slide film, it's not bad. So I go to Canon's web site and peruse MTF curves. MAMA MIA, what a load of crap! Short of long fixed-focus teles with "L" in the name and ED glass inside, they ALL look the same crap. Even most L series zooms look crappy, some even at f/8. Many are worse than the cheap kit lens! Are any of these (non fixed focus tele) lenses REALLY do better than others, when applied to the 30D body with its bloated pixels and Bayer filter? "Better crap"? I have ordered up the Canon 50 mm f/1.8 which should serve for low light, as I like mild teles. Doug McDonald You have rediscovered the wheel: fixed focal length lenses are better than zooms. So what? The Canon 18-55 is just not a good lens, possibly the worst of the major brand dSLR kit zooms. So what? Well, that's one you should have known. In any event I am increasingly convinced that absolute lens quality in the digital age is not the factor it was in the film age. The ultimate quality of a digital image is as much or more dependent on post-exposure processing than it is on what, beyond the basics, occurs when the shutter is pressed. The worst defect a lens can have in the digital age is chromatic aberration. In your Canon 18-55 you have the poster child for chromatic aberration. Even so, all is not lost as many images can be saved with simple image processing. > You have rediscovered the wheel: fixed focal length lenses are better than > zooms. > So what? > The Canon 18-55 is just not a good lens, possibly the worst of the major > brand dSLR kit zooms. > So what? Well, that's one you should have known. But my point is that from teh MTF curves, their other zooms are just as awful, if not worse. > The worst defect a lens can have in the digital age is chromatic aberration. I take it you man LATERAL chromatic. > In your Canon 18-55 you have the poster child for chromatic aberration. Not really. It's actually not bad at all compared to many lenses I've seen. > Even > so, all is not lost as many images can be saved with simple image > processing. That's the point: lateral chromatic is only an issue now to the extent that it blurs out one color. The color fringes can be fixed easily, to first order. You would think that, ASSUMING, which may be a bad assumption, that all examples of a given lens design are the same in the lateral chromatic department, the computer software for a given company would automatically use the camera data stored in the files, along with a table of lens data, to fix the color spread from the lateral chromatic, to first order. But apparently they don't do this. NOTE: is this patented? It's the sort of obvious thing that the patent office issues patents for these days. Doug McDonald >> You have rediscovered the wheel: fixed focal length lenses are better >> than zooms. [quoted text clipped - 30 lines] > obvious thing that the > patent office issues patents for these days. There are excellent third-party programs that correct not only for lateral CA, but pincushion/barrel distortion and other zoom lens shortcomings. I think the reason camera manufacturers don't provide such software is probably because they are camera manufacturers and not software engineers, and they want to keep it as simple as possible for most users. The posters in these groups are, by and large, the most informed and discerning camera users there are; it amazes me at times what non-photogs, or casual snapshotters will accept as good. They just don't see the technical faults in their shots - let alone compositional, lighting, camera shake, and other errors which stand out to knowledgeable types. For an example of high-end correction software, take a look at http://www.dxo.com to see what software correction can do to an image. I shoot RAW with a 300D and a 17-85 USM IS zoom, and all my shots go through DxO before I even look at them. The uncorrected shots look like crap beside the corrected ones. Colin D.  SignaturePosted via a free Usenet account from http://www.teranews.com > I just bought the old 30D camera (one week before the XTi is announced, > and I can't return the thing for free, argh), with the standard zoom > lens. (I do love the body, however, so maybe the extra $500 is OK). Wow, a camera that's been out for 6 months is "old". My Rebel XT must qualify for ancient. Greg Signature"All my time I spent in heaven Revelries of dance and wine Waking to the sound of laughter Up I'd rise and kiss the sky" - The Mekons >I just bought the old 30D camera It's still current. >(one week before the XTi is announced, It replaces the 350D, not the 30D >and I can't return the thing for free, argh), with the standard zoom >lens. (I do love the body, however, so maybe the extra $500 is OK). What makes you think the 400D is better than the 30D? Or perhaps I should ask why you think the 30D was photographically better than the 350D but not as photographically as good as the 400D? >I've extensively looked at pictures made by the 18-55 >zoom, and it appears to be a perfectly ordinary commercial zoom lens. W-e-l-l- yes, what did you expect for the price? >That is, it's crap compared to a 50mm f 1.8 non-zoom, or my 270mm >apo-Symmar, especially at the wide end. But with the digital body >rather than 50 speed Fuji slide film, it's not bad. So, it isn't actually "crap", just not as good as better lenses. >So I go to Canon's web site and peruse MTF curves. >MAMA MIA, what a load of crap! Short of long fixed-focus teles with "L" >in the name and ED glass inside, they ALL look the same crap. Even most >L series zooms look crappy, >some even at f/8. Many are worse than the cheap kit lens! So you have noticed that zooms are not as good as primes; have you actually taken any photographs? >Are any of these (non fixed focus tele) lenses REALLY do better than >others, when applied to the 30D body with its bloated pixels and Bayer >filter? "Better crap"? Undoubtedly some are better than others. >I have ordered up the Canon 50 mm f/1.8 which should serve for low >light, as I like mild teles. Seems a good choice, it is on my list. I have recently migrated from film where I had: 28mm f/2.8, 55mm f/1.8, 105mm f/2.8, and 200mm f/3.5 to digital where I have just purchased a 17-85mm (27-136mm) f/4-f/5.6, and plan to purchase a 75-300mm. I seldom carried more than two lenses because of the weight, and probably will not change that policy, although the new flash is lighter so I might carry a third, but it would be nice sometimes to have a faster lens. SignatureIan G8ILZ >> So I go to Canon's web site and peruse MTF curves. >> MAMA MIA, what a load of crap! Short of long fixed-focus teles with [quoted text clipped - 4 lines] > So you have noticed that zooms are not as good as primes; have you > actually taken any photographs? I noticed that long ago. What surprised me was that many of the very expensive "L" series zooms did not look any better at f/8. Obviously many are "better" lenses since they are about the same MTF crap level at say f/2.8 as the cheap lenses are at f/4 or f/4.6. But I expected really good performance at f/8 from the very expensive lenses. Doug McDonald > >I just bought the old 30D camera > [quoted text clipped - 44 lines] > to digital where I have just purchased a 17-85mm (27-136mm) f/4-f/5.6, > and plan to purchase a 75-300mm Without exception, all OEM and aftermarket 75-300mms are rotten lenses. I saw a comparison between a bunch of them and a high-end 50-200 and the results were not pretty. Even in a magazine the differences were glaring. My guess is that most of them come out of the same factory in China. > I just bought the old 30D camera (one week before the XTi is > announced, and I can't return the thing for free, argh), [quoted text clipped - 22 lines] > > Doug McDonald I think they need to get back to shorter range zooms. Maybe 1:2 or 1:3 at the most. I've got an old Olympus 100-200mm zoom and at f8, it is very close to a prime lens. Even with the best coatings, lenses with 14+ elements are "feeding" each other their errors resulting in a cumulative error rate and contrast reduction that cannot be avoided. In the "old days" people expected most zooms to produce poor quality relative to fixed lenses but now they don't use fixed lenses very much (the average shooter) and they settle for less than stellar results. > I think they need to get back to shorter range zooms. Maybe 1:2 or 1:3 > at the most. [quoted text clipped - 6 lines] > relative to fixed lenses but now they don't use fixed lenses very much > (the average shooter) and they settle for less than stellar results. This may generally be true (and the Nikkor 75-150mm f3.5 E and 85-200mm f4/4.5 were exceptionally good for fairly inexpensive zooms (as were some others, like the 25-50mm f4, etc.), but the Nikkor 17-35 f2.8 (see http://www.ferrario.com/ruether/wa-zooms.htm), 80-200mm f2.8, and (by reputation) 28-70mm f2.8 zooms are so close in performance to the best of Nikon's non-zooms that the differences aren't very important (but the size/weight/prices are, alas...!). Many good zooms exist, but it does seem to me that most of the newer Nikkor zooms, except for the very expensive ones, have declined in relative image quality (I tried three 24-120mm VR samples and returned all of them - I wish I had not sold my non-VR version!) and I kept one sample of the small 24-85mm, but I don't like it - my old 35-105mm f3.5-4.5 MF is very noticeably better than it and my optically different AF version. There are several other examples of this in my collection (BTW, I have a lens evaluation list, at www.ferrario.com/ruether/slemn.html) -- David Ruether ruether@verizon.net rpn1@cornell.edu http://www.ferrario.com/ruether |
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