Sell EF 17-40 f/4 and get EF-S 17-55 f/2.8?

[thekingb]

And it's especially untrue in the case of the 17-40. Even the $100 kit lens is sharper. This urban legend persists because of two common flaws in the method used to compare different format sizes: using different iris diameters and different magnifications. These factors must be equalized between sensor sizes to provide any sort of useful comparison baseline, and when that is done, it becomes clear that larger sensors are sharper (usually by even more than you would expect based on the lens price differential).
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I am really curious to hear more about this. You mention "larger sensors." I certainly agree that full frame sensors generally produce better, sharper images that resolve more detail (and I would have a FF body if money were no object). But I think you are saying something different above, although I am not sure I follow you. Please elaborate. I am by no means an expert or even amateur when it comes to optics, so I'd love to hear more.


Remember, though, that the only relevant comparison for me is the overall IQ of two different lenses on my 7d. You seem to be saying that the 18-55 kit lens would produce a better (or at least sharper) image on a 7d than the 17-40. Are you saying that would be true at identical focal lengths (ie, at say 24mm on each lens)? Or when you adjust focal lengths for the crop factor (ie at 17mm on the kit and 27mm on the 17-40)? In either case? My experience doesn't bear that out. Although the 18-55 is surprisingly good for a cheap lens, the color and contrast of the 17-40 far exceed the kit lens; and there's only so much sharpness the eye can manage anyway.


And are you saying that EF-S lenses will always be better on crop cameras than EF lens in the same/similar focal range?


Thanks!


Brian

[Mark Sanderson]

The EF-S holds it's value very well, in fact I sold mine about a month ago for more than I paid in 2008 []

[scalesusa]

I had the 17-40mm L as well as the 17-55mm. The 17-55mm stayed on my 40D all the time. Eventually, I used the 17-40mm on my 5D MK II, but while good, it just did not seem to be that good, so I sold it and bought a 17mm prime and a 35mm L.


Unfortunately, I found that after buying the 35mm L, the 40D just gathered dust so I sold it and later reluctantly sold the 17-55.

[gbc]

Just throwing my support behind the 17-55. It is a wonderful lens. I will say, though, that a few times when I'm leaving the house, that I debate whether or not to take it with me, because it is pretty darn heavy, and big. Sometimes I just grab my zooms and primes, and then my s90 for wide shots. I kind of wish I still just had my 18-55 kit lens for times when I'm shooting in good lighting and don't need a really shallow DOF. But when shooting in low light, the 17-55 has been outstanding. A lot of great shots at concerts with this lens, and the IS definitely makes a difference. I debated the 17-40 for a long time, and the fact that I shoot a lot of low light shots was the deciding factor.


One thing I recently discovered, though, is what a great lens it is for video on the 7D. Great DOF for video, and pretty good focal length range for most shots.


Also- I'm on my second copy. The first one was really bad at the wide end, even after microadjustment. Both copies were from Adorama refurbished. The second one seems much much better. But definitely check out the focus at both ends when you get it.