Alex writes to ask about the Canon EF-S 10-22mm f/3.5-4.5 USM:

I’ve been reading your blog for a while now and have noticed that you haven’t commented on the Canon 10-22mm lens on a crop camera. I have a 350D with the 10-22mm lens. I’m curious as to your opinion on using this lens on a crop body compared to the 17-40mm. I’m considering upgrading to the 5D at some point and would obvioulsy need to purchase a WA lens as well. You seem to be satisfied with your result of using the 17-40 on a crop body in the past or did it make a noticeable difference to you when you moved from the crop body to the full frame on the 5D with your 17-40mm?

Thanks for writing, Alex. You are right that I haven’t written about this lens, but only because I don’t have any direct experience with it. Being an EF-S lens, it is designed for use only on crop sensor Canon bodies (like the 350D/400D series and the 20D/30D/40D series), and I’m using full frame these days.

You are also correct that I’m a big fan of the Canon EF 17-40mm f/4 L lens. I used this lens on the crop sensor camera that I had until about a year ago, and I continue to make a lot of use of this lens on my 5D. On my crop sensor body, the 17-40 always produced excellent center sharpness, though it could be a bit soft in the corners, especially when shot wide open. I find it to be even better on full frame where I frequently shoot it at f/11 or even f/16, thus controlling the corner softness/fall-off issues more effectively.

On a crop sensor body, the 10-22mm focal length range is essentially equivalent to the 16-35mm range on a full frame body – in other words just a tiny bit wider than my 17-40mm lens on full frame. Although I had thought that 17-40mm was “wide enough” on my crop sensor body, once I started shooting full frame with this lens I really came to appreciate the much wider coverage provided by this combination. I think that the combination of the 350D and the 10-22mm lens could very useful – for example, it could be a wonderful small and lightweight setup for doing landscape photography while hiking or backpacking.

With that in mind, I guess you could say that I was satisfied with the 17-40 on the crop sensor camera at that time, but that I know realize that if I were going to again use a crop sensor body I would almost certainly want to get a lens providing the coverage of the 10-22. Although I haven’t used the EFS 10-22mm lens myself, almost everything I’ve read about it has been positive.

When you do move to that full frame body you might find that the 17-40 really comes into its own, especially if you shoot landscapes and similar subjects. As to whether you would want to get this lens now or wait, I think that depends upon what kind of coverage your other lenses currently provide in that range.