Is this normal for 17-40 L lens on full-frame?

<p>Hello All,<br>

I did some lens tests over the weekend because I was a bit unhappy about my 17-40L on my 5DII in the corners. I have attached a screen snap which shows at 200% the top left and top right corners at f8, firmly on a tripod using manual focus and live view. Please accept that the setup was fine. I also tested the 24-105, 70-200, 50 and 100 m and all were 100%. Does anyone else see this sort of deterioration in the top right with this lens? It is fine at f16. Thanks, Alan</p>

<p><img src="webkit-fake-url://D3271C8F-C8C5-4767-B536-FC9CB6332A68/image.tiff" alt="" /></p>

<p>Where is the "screen snap"?</p>

<p>Your image is not showing. You also didn't say what focal length you were shooting at. It's pretty normal for ultra-wide lenses to not be as good in the corners as longer lenses -- even 24mm offers a significantly narrower field of view than 17mm. That said, I was generally happy with the results I got with the EF 17-40mm f/4L even at f/5.6.</p>

<p>If the top right and left are equally unsharp (long with the bottom left and right), then it's probably fine. If you have to go to 200% on-screen to see the difference, then I wouldn't worry about it either.</p>

<p>If one corner (or two corners) is/are <em>noticably</em> worse than the others, then the lens may be misaligned.</p>

<p>Seeing the images would help.</p>

<p>another classic error: a not "perfectly" installed hood...</p>

 

The new DPP with DLO does help the 17-40 corners.

Out of focus areas become a bit grainy though.

<p>I have the 17-40 on a full frame and I find that at 17mm the corners are really bad (unsharp) from f/4 to f/8. This concers all corners evenly.<br>

At f/11 sharpness at the corners becomes acceptable.<br>

I have tested 3 different 17-40 lenses before I decided to buy the one that I have now. I though the corner issue was a problem with a specific lens, but after testing and reading up on the subject it seems that unsharp corners are simply a "feature" of this lens.</p>

<p>Hello All,<br>

Many thanks for your comments. Sorry about the missing screen snaps. I hope it is OK this time. The lens was 17-40f4L at 35mm f8, no hood!, solid tripod, live view, manual focusing. Both images are at 200% but I can still see clear differences at 100%. The photos are in the 17-40 lens test folder (http://www.photo.net/photos/Alan_Hogg). "left" jpg is upper left corner, "right" jpg is upper right corner. Thanks for your comments. Alan</p>

<p>I cannot see the example, but why in the world would you be "testing" at 200%!? You'll never make a print at close to the size that this represents.</p>

<p>Dan</p>

<p>If you are seeing difference between corners, first confirm that the target was truly parallel to the sensor plane. If the problem still exists, it is possible that you have a lens that need to go back to Canon for adjustment. Sometimes the lens can become decentered and one side or corner will be softer.</p>

<p>Dan</p>

<p>My 17-40L is slightly softer on the upper left side in way that is similar to your crop. I'm sure this indicates the need to send it to Canon for a tune up, which I plan to do now that I've upgraded to Gold CPS. I dropped it on the pavement in Yosemite. Everything else works fine. It's a tough lens. </p>

<p>G Dan Mitchell makes a wise point about having the plane of your sensor parallel to the plane of the wall. This can be difficult to ascertain.</p>

<p>Rather, why don't you go out and shoot the horizon at infinity? That's often how I test lens decentering issues. The Canon 17-40 & 16-35 are notorious, for these sorts of problems, IMHO. A couple days ago, I pitted the Nikon 14-24 at f/2.8 against a new copy of the 16-35 f/2.8II. I used a cheap Nikon-Canon adapter that rattled when the lens was on, you'd think giving a disadvantage to the Nikon 14-24.</p>

<p>Nope. It took f/16 on the Canon lens to get it to match f/2.8 edge-to-edge sharpness of the Nikon lens. But don't take my word for it, see for yourself (all images shot on 5D Mark III):</p>

<p>Left side of frame, 100% view, <strong>Nikon @14mm|f/2.8</strong> on left, <strong>Canon @16mm|f/11</strong> on right:<br>

<img src="http://cl.ly/G3k9/Nikon14-24_vs_Canon16-35_Left.jpg" alt="" width="800" /><br>

<a href="http://cl.ly/G3k9/Nikon14-24_vs_Canon16-35_Left.jpg">Link to full-size image</a></p>

<p>Right side of frame, Nikon on left, Canon on right:<br>

<img src="http://cl.ly/G3bg/Nikon14-24_vs_Canon16-35_Right.jpg" alt="" width="800" /><br>

<a href="http://cl.ly/G3bg/Nikon14-24_vs_Canon16-35_Right.jpg">Link to full-size image</a></p>

<p>Please view at 100% by following the links to really appreciate the differences. Apologies also for the flare on the Canon shot, as the sun had sunk further, or maybe it's more prone to flare, I'm not sure. Shouldn't really detract from the comparison though... it's pretty obvious that the Nikon is far superior & that's the understatement of the century.</p>

<p>Just to reiterate: that's<strong> f/2.8</strong> on the Nikon vs. <strong>f/11</strong> on the Canon. And the 14-24 still wins. This sort of performance is what I've come to expect from Canon's wide zooms. My Canon 24-70L, on the other hand, is absolutely stellar edge-to-edge at almost all apertures. I don't know what it is with the 17-40 & 16-35... I've always had exceptionally poor performance from those lenses.</p>

<p>I'm on the fence about switching to Nikon at this point after doing this comparison. Although I'm considering purchasing the $240 Novoflex adapter that allows for aperture control, then using the Nikon 14-24 on my Canon... no AF then though...</p>

<p>-Rishi</p>

<blockquote>

<p>I don't know what it is with the 17-40 & 16-35...</p>

</blockquote>

<p>I used to own the Canon EF 17-40mm f/4L USM. Lousy at the corners. I now own the Canon EF 16-35mm f/2.8L II USM. It is an improvement, but still not a stellar performer at the corners. The Nikkor 14-24/2.8 is a winner that Canon should have as an equivalent in their line up.</p>

<p>Thanks for your opinion Peter. Good to know I'm not alone in being annoyed by Canon's wide angle zooms.</p>

<p>Those comparisons I posted are actually from the middle of the frame, on either extreme left or right side. Not even the corner...</p>

<p>-Rishi</p>

<p>I don't know about you, but my 17-40 F4L is extremely sharp with very little vignetting in the corners on my Canon 5D Mark II. Much better at 24MM than the 24-105 which has both vignetting and horizontal line distortion issues.<br>

I primarily shoot at F4 with my 17-40 and it is just a nice sharp lens with great colors and excellent build. It is also the main lens I use for shooting music videos and it just works well no complaints at all.<br>

Here is an example of the amazing sharpness I get from this lens even hand held.<br>

http://www.photo.net/photo/9444451<br>

http://www.photo.net/photo/9444434</p>

<p>Care to post any edges/corners? That's an enlargement of the center, and even then, doesn't look that sharp to me (though I'm not sure what exactly was in focus).</p>