Help! I think I got a bad 16-35

[friedmud]

Help!  Just received my 16-35 f/2.8 II... and I think I may have received a bad copy.  It is unbelievably soft on the left hand side (and not great on the right).

I am shooting with a 7D and really did not expect to see much, if any, falloff in sharpness due to the crop.  Please, if you have a 16-35 and a 7D, please let me know if this is normal or not.  I'm really thinking about dropping this thing back in the mail tomorrow to try to get a new copy...

Here are a couple of full sized, untouched JPEGs from the RAWs I shot this afternoon.  Look on the left hand side... especially going toward the upper left corner...

Exposure   0.001 sec (1/1000)
Aperture   f/2.8
Focal Length   16 mm
ISO Speed   100
http://farm8.staticflickr.com/7215/7162586786_902d2be46a_o.jpg

Exposure   0.003 sec (1/400)
Aperture   f/4.5
Focal Length   16 mm
ISO Speed   100
http://farm8.staticflickr.com/7212/7162590958_1d6f4a284b_o.jpg

I think this last one demonstrates it the best.  It was shot at f/7.1 which should definitely be pretty good in this situation.  The focus was basically right in the middle of the frame.  Just take your eye from the middle of the frame, straight to the left and watch what happens on the rocks...

Exposure   0.003 sec (1/320)
Aperture   f/7.1
Focal Length   16 mm
ISO Speed   100
http://farm8.staticflickr.com/7223/7162594740_f0b313beb3_o.jpg

I can't imagine what it would look like on a FF camera!  The left 25% of the frame would be unusable.

This is crazy for $1,600!

Please give me some feedback here... I need to know if I'm crazy...

[friedmud]

Anyone out there with a 16-35 on a crop body that can comment?

[neuroanatomist]

Looks like decentering to me, I'd exchange it. 

I don't really use my 16-35mm II on my 7D, I use the 17-55mm f/2.8 IS instead.  But here's a 100% loupe view of the extreme left side of an image (symmetrical with the juice bottles on the right in the full image) from my 5DII at 16mm f/4.5 - the barrel distortion is quite bad, but the sharpness is decent even at the edge on FF.

[friedmud]

Thanks neuro.

I have a 17-55 f/2.8 IS as well.  But... it's broken right now (seized up zoom) and it's always had a problem on the right hand side of the frame (REALLY soft... way worse than this 16-35).  So, instead of putting money into that I figured I would get something weather sealed and that will work on FF.

Of course, the 17-55 is unbelievably good optically (except on the right in my copy!)... I know I'm going to miss a bit with the 16-35... but I don't want it to have obvious problems...

Thanks again for your reply - it's going back today.

[wickidwombat]

yep looks like decentering that second pic of the bricks shows it pretty well, the others its not so easy to see

[friedmud]

New lens will be in on Monday... I'll definitely post some samples from it!

[Vossie]

Just curious as I also have a 16-35 on order: was this covered by warranty?

[KreutzerPhotography]

I shoot a 16-35 II on a 50d and dont get that much CA. My only "issues" with the lens are from distortion. But That is expected.

[friedmud]

Well... I got the second one in... and I think it's "worse" than the first one...

http://farm8.staticflickr.com/7225/7200555090_cbf80747a8_o.jpg

It may be a bit better on the left (not by much)... but overall the resolution is less (sigh).  I'm going to take it out shooting tomorrow and see what's up.... but this is definitely disappointing.

Vossie... no warranty needed.  I only had it in my hands for about 12 hours... just shipped it back to the seller for exchange.

Not sure what I'll do this time...

[wickidwombat]

actually now you mention it, thinking back to my first 5Dmk3 that i returned the left to right hand sides seemed "off" on all my lenses I didnt really worry too much since i couldnt get it sharp in the center to start with but perhaps that camera's sensor was out of alignment something like this could explain what you are experiencing, do you have other lenses to test, very very odd that 2 16-35 would be bad in a row?

[helpful]

Wish someone would have told you that the bad part of the image was out of focus and saved you from sending off and getting a second "bad" copy of the lens.

The fact it is out of focus can be differentiated from lens sharpness or lens aberrations by the way the image looks. It is really weird that it is out of focus, however. It could be the camera sensor as someone mentioned.

There are two aspects in which the sensor might be to blame. Part of it is just the sensor is not very sharp, as you can see even in the center of the frame. The Canon 7D does not have the best sensor. No matter how low of ISO you go there is always some mushiness at pixel level. But clearly the center of your images are much sharper than the left side. So there is more to it than sensor image quality. Maybe there is also an issue with sensor alignment.

One way to find out if the lens is sharp on the left side, and the sensor is skewed, is to use live view to focus, and move the focusing box to the left side and center it on a very well-defined subject/object in the image. Use a tripod when doing live view to make extra sure, because hand movement does affect the camera's ability to determine the exact focus. The live view focusing mechanism feeds directly from the image sensor, so even if the sensor is out of alignment, it will still obtain focus on the sensor for the desired object--but then the rest of the frame might be out of focus.

It could be field curvature, but your f/7.1 image ought to have had plenty of depth of field to deal with that problem.

Wide angle lenses are notorious for their need to have the camera they are mounted on built to super precise lens mount tolerances. They have a lot of depth of field, but the back focus distance is so short (hint, due to the short focal length) that just a few millimeters can change focus from infinity to a few inches away.

For the photographer this means depth of field is very generous, but for the camera manufacturer, it means the lens mount has to be ultra carefully made to line up exactly with the corresponding lens. People have had similar trouble with the Nikon 14-24mm.

[friedmud]

Thanks Helpful and Wombat.

I do agree that it is "weird" that I got two in a row that are off on the left.  I agree that it seems like something else must be wrong.

However, I can't see this with any of my other lenses.  In particular, my 70-200 is ultra sharp all the way across the frame... and my 17-55 f/2.8 is great on the left (although soft on the right... but it was also soft on the right with my XSi).

The next thing I'm going to do is actually go test this lens on my XSi.  The sensor is much more forgiving... but if there really is something wrong on the left it should still show up.  If it doesn't, then it might be a mating issue with the 16-35 and my 7D.  Indeed, I did notice that this lens is really "tight" when I go to lock it in... so there might be something to that.  Could need to send the body and lens off together to have them adjusted...

I will also try live view focusing on the left... I hadn't thought of that.

Thanks for the tips - I'll try them out and get back to you guys.  BUT it won't happen until tomorrow because Diablo 3 came out and that's what I'm doing for the rest of the evening ;-)

[neuroanatomist]

BUT it won't happen until tomorrow because Diablo 3 came out and that's what I'm doing for the rest of the evening

Clearly, your priorities are out of whack. Really, just live with the soft left side, or better yet, get a PowerShot and just shoot auto-mode jpgs.

 

Let us know what happens...

[sarangiman]

FYI I finally took the plunge & sprung for the Nikon 14-24/2.8 + Novoflex G EOS Adapter.

On my 5D Mark III, 1 copy of the Canon 16-35/2.8 & 2 copies of the 17-40/4 needed f/11-f/16 to get the edge to edge sharpness that I get on the Nikon 14-24 at f/2.8.

I don't think any of the Canon wide zooms that I've tested have ever, at any aperture, gotten as sharp/even across the field as the Nikon 14-24 by f/4-f/5.6 (b/c diffraction starts limiting resolution at those high f-stops, especially on shorter focal length lenses).

My 17-40/4 was sent to Canon FSC b/c the left side was severely softer than the right. It was softer than the right even at f/18. When I got it back, it appeared to have been fixed (though still required f/11 for the kind of performance I see on the Nikon 14-24 at f/2.8 ). A couple weeks later, the right side became severely soft compared to the left. And it had just been sitting in my bag at home in between (no drop, no abuse, nothing).

So I wonder if it's both a design & quality control issue.

I gave up & went for the Nikon 14-24. With Canon's stellar Live View implementation, it's a cinch to focus. Auto-exposure even works just fine (no Auto ISO though). The Novoflex adapter gives me aperture control.

Here's a comparison (left edge, center) of the Nikon 14-24 at f/2.8 (left) & Canon 16-35 at f/11:

View full-size here: http://cl.ly/G3k9/Nikon14-24_vs_Canon16-35_Left.jpg

And here's the right edge, center:

View full-size here: http://cl.ly/G3bg/Nikon14-24_vs_Canon16-35_Right.jpg

The Canon lens is at f/11 b/c that's the aperture at which at least started to look sharp at those edges. There is more flare in the Canon shot b/c the sun had sunk lower, but I think you can still easily see the sharpness difference.

So, in a nutshell, I'm not at all surprised by your results. Others do make a valid point though that you should check if this happens with all your lenses (better to test similar focal length lenses... especially wide-angles)... if so, then your sensor or lens-attachment ring could be imbalanced.

[friedmud]

sarangiman: Thanks for the post... that makes me feel better because I sent the (second) lens back today for a refund.  I just couldn't bear the edge sharpness for $1,600... and on a 7D!  No excuse for a full-frame lens not to be sharp all the way to the edge on a crop body... especially not for $1,600...

The sharpness on that Nikon is incredible!  Especially at f/2.8!  Wow!  I love the 14-24 range as well... perfect for what I'm going to be using it for... Landscapes.  I don't need autofocus in my ultra-wide... I always do all of my landscapes using manual focus anyway.  I'm really going to have to look into that.

In the meantime... I've decided to send my 17-55 f/2.8 IS in to have the zoom fixed and see if they can do something about how soft it is on the right.  That lens is badass other than the softness on the right... super sharp everywhere else and f/2.8 + IS makes it very handy in a lot of situations.  I guess that I've learned that what I already had was really pretty awesome and I didn't appreciate it ;-)