Much better than I anticipated

Rock and Rollei wrote:

shleed wrote:

Rock and Rollei wrote:

I've had the 17-40 for years, but never been outstandingly happy with it. Stopped down to f8 or f11, and it's really rather good - so it's been great for landscapes, and if that's what someone wants it for, I would recommend it. At wider apertures, it's nothing special. So it's a bit of a one-trick pony; does that trick very nicely, but is not an all-rounder like the 16-35 f4 L IS.

It is certainly for landscape purposes, and IR work. Canon's 16-35mm lenses tend to have severe hotspots in IR, which is a much bigger issue than edge sharpness for me. I couldn't find information on whether the 16-35 f4L IS was good for IR or not. I could have tested, but it's difficult since IR performance varies a lot more than visible light in terms of weather etc.

For normal purposes I'd agree with you and would have got the 16-35 f4L IS instead, mainly for low light work. But again, the type of photography I do often warrants a tripod since exposures can be in the minutes.

Both of my IR DSLRs are APS-C, so I tend to use my 15-85 mostly with them, so hadn't spotted that.

Depends on the lens design. Most these days are optimised only for visible light.

I used to use my 10-22mm for IR on my 7D and 40D, and it did the job well in the sense that it wouldn't produce hotspots at small apertures. The problem I had with it however was the severe chromatic aberration that would only appear in IR. This was made worse when I used it on my 6D after doing modifying it for FF use, as the severe chromatic aberration in IR was amplified even more. There was also a lot of ghosting.

My 17-40mm exhibits similar chromatic aberration in IR, but nowhere to the same extent. The results are sharp but I've yet to do more than test photos with it in IR light at this point due to the abysmal weather conditions. Hotspots are nonexistent no matter what aperture I use, which is brilliant. It's in line with the rest of my lenses in this regard.