According to Imaging Resource the 16-35mm f/2.8L II lens sharpness is subjectively worse than 17-40mm f/4L on full-frame. Here are the Blur diagrams for 16-35 and 17-40 on FF. So, analysing this, the 16-35 is horrible on F/2.8 and less sharp on F/4 than 17-40. But these are just scientific conclusions. What could you say from your experience on these lenses blur and, say, colors or picture in general?

  • \$\begingroup\$ Do you always plan to shoot only at 16mm or 17mm and with wide open aperture? \$\endgroup\$
    – Michael C
    Jul 10, 2016 at 10:46
  • \$\begingroup\$ Sometimes this is interesting when shooting at bar or cafe. And if 16-35 is more blurry, there's no point in buying it in favour of 17-40. \$\endgroup\$
    – igorp1024
    Jul 10, 2016 at 17:57
  • 1
    \$\begingroup\$ Be aware that a Canon EF 16-35mm f/2.8 Mk III is rumoured to be announced soon. Also, I have the cheaper EF 16-35 f/4 and find it to be ridiculously crispy in the corners even wide open. \$\endgroup\$
    – Bobulous
    Jul 17, 2016 at 18:36

2 Answers 2


I had them and shot them side by side and the 16-35II was hands down better in the ability to clearly resolve and separate details. The color was more lively, too.

I think both are great for people photography, but if you want landscapes with perfect sharp corners, you may want to look further. The 17 and 24 T&S lenses are quite good, so are ~20mm lenses from Zeiss.


The comparisons between the EF 16-35mm f/2.8 L II and the EF 17-40mm f/4 are a fairly mixed bag. It may well be that copy-to-copy variation of the same model is just as great as the difference between samples of two different models as tested by a reviewer. You can also throw the much newer EF 16-35mm f4 L into that mix as well.

At some focal lengths and apertures (such as widest focal length and aperture) the 16-35mm f/2.8 is the weaker, the 17-40mm is in the middle, and the newer 16-35mm f/4 is the strongest. Wide open FL and wide open f-number

At other focal lengths and apertures they are much less different. 28mm f/5.6

At 16mm and f/5.6 the 16-35mm f/2.8 is very good at the center and not good at all in the corners as tested by DxO Mark.
16mm f/5.6

The tests at Imaging resource to which you linked does not reflect this same eccentricity. Neither do the image quality comparisons at The-Digital-Picture, where the 16-35 f/2.8 looks generally better than the 17-40. As Roger Cicala often points out, the state of a lens' elements being in proper adjustment or not can have just as much to do with how the lens was handled by the shipping courier as they do with how well they were adjusted before they left the factory or service center. Since he is the founder and chief lens guru at lensrentals.com he probably has about as much experience with lenses that have been shipped frequently as anyone else on the planet.

I own and have used the 17-40 extensively. I've never owned the 16-35 f/2.8 II and have used it only sparingly. In my opinion the only major difference is the maximum aperture. When you're in very low light and need that extra stop just to get anything usable you don't worry so much about the slight differences in acutance or CA (Where the newer 16-35 f/4 is better at most focal length/aperture combinations than the other two).

If you are primarily concerned with keeping a subject near the center of the frame sharp and aren't worried about the out of focus areas near the edges and corners any of these lenses do a pretty good job. They're all very good in the center but the performance drops off to one degree or another near the edges.

If you are looking for a lens to do large display sizes of commercial quality landscapes none of theses lenses are what you probably need. To get that kind of quality you should look at wide angle primes, but be prepared to pay significantly more for better optical performance. If you don't need autofocus, any automated or semi-automated exposure modes, or the higher build quality of the Canon "L" series then you can get about the same optical performance at a much lower price for a lens such as the Samyang/Rokinon/Bower/whatever (other name it's being marketed under) 16mm f/4, 24mm f/1.4, and 35mm f/1.4 primes

I've used the 17-40 to do astrophotography with moderately good results. The stars near the corners and edges do start to show coma a bit. Canon 5D Mark II, ISO 3200, 17mm, 15 seconds at f/4. Looking almost directly overhead shortly after a near full moon had risen in the east. The image was edited to be viewed in a dark room, so it does look rather dark when viewed on a white background. (Resized from 5616x3744 to 1536x1024) starry sky

It also does fairly well in brighter light. Canon 5D Mark II, ISO 800, 17mm, 1/160 sec at f/4. This image was fairly heavily processed including lens distortion correction and some tone mapping of the raw file. (The lens correction increased the resolution from 5616x3744 to 5811x3874 which was then resized to 960x640 for web viewing) afternoon practice


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