Check for decentering on your new lenses!

This is the 3rd lens I have received new lately which has been decentered. All Canon zoom lenses.

With the latest purchase of a telephoto zoom and UWA zoom lens, I could see even through the viewfinder of the 6D that one side was soft. After a round of test photos in various conditions with IS on and off, it remained always the same. The 15-85 was the worst decentering I have ever seen, but this one is just bad enough to bug me. My 16-35II, while softer in the corners by design, is at least equal enough to my eye, that I can tell no difference.

When you get a new lens. Go outside in good light and get the camera on a tripod or high shutter speed like 1/2000 th. Find an object with sharp details, like a license plate, and shoot it from around 50-100 feet away with the lens stopped down a little. Put it in all 4 corners for 4 photos and then import them into photoshop, cut them and put the corners next to each other. It should be apparent which side is softer if any. Do this for several different setups just to make sure it isn't a fault in your testing.

Next, send it back to Canon if off center.

I don't know if Canon has been slipping on QA lately or I just had bad luck. But in all the gear I have purchased in my life, I never had bad copies. Lately I have been sending faulty gear back way too often.

The black marks are to hide part of my neighbor's license plate.

UWA = good to go! Even if soft in the corners, it is at least even, which is all I care about.

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All on the same body?

Andrushka wrote in post #15584659
All on the same body?

Should be so, IMO, for the test to be conclusive.

I am confused it seems you mention your using a 6D and also a 15-85..how can you even do this the 15-85 is EF-s

My 24-70 II was decentered brand new. Right side of the image was softer no matter the aperture. Compared to the left which was very sharp.

I sent to Canon and they basically told me they could not correct it. So I exchanged the lens with who I bought it from. The replacement is perfect edge to edge. I was very happy with the exchange!

That was the only lens that I noticed any decentering issues with though. All lenses will have it to some degree (non are flawless, but some may be undetectable to the eye). As long as it is not obvious, no real problem.

agedbriar wrote in post #15586525
Should be so, IMO, for the test to be conclusive.

05Xrunner wrote in post #15586532
I am confused it seems you mention your using a 6D and also a 15-85..how can you even do this the 15-85 is EF-s

Exactly why I asked

My dad has a t1i. Which was getting a 15-85. But that lens sucks no matter is decentered or not. The lens barrel on those things allows zoom creep and the front element can't stay straight because the lens droops down when fully extended. Good optics, but the build quality is insufficient even for the price. I rented another one and it was the sloppiest POS I have ever seen, so they get even worse over time.

Both new zooms tested on 6D. 6D is flawless.

B&H are giving me another copy of 70-200.

Canon_Lover wrote in post #15591374
My dad has a t1i. Which was getting a 15-85. But that lens sucks no matter is decentered or not. The lens barrel on those things allows zoom creep and the front element can't stay straight because the lens droops down when fully extended. Good optics, but the build quality is insufficient even for the price. I rented another one and it was the sloppiest POS I have ever seen, so they get even worse over time.

Both new zooms tested on 6D. 6D is flawless.

B&H are giving me another copy of 70-200.

Something smells funny...

Why don't you tell us what lenses exactly you tested on which body?

And the 15-85 is regarded as a great lens...

pyrojim wrote in post #15591501
Something smells funny...

Why don't you tell us what lenses exactly you tested on which body?

And the 15-85 is regarded as a great lens...

I appreciate that you guys are trying to help, but I am expert enough on gear to know that testing lenses should be done on the same body.


Both zoom L zooms tested on 6D. 15-85 in t1i.

The 15-85 is only good optically when not decentered. Other than that, the build quality of the zoom barrel is sub-par. Especially considering the price. Image quality when new is only a fraction of what makes a lens great. I am not the only person who feels this way about the 15-85's build quality. Most people I think who buy it, wouldn't care anyways about zoom creep and barrel wobble.

My old 15-85 was also decentred slightly, although not as bad as the two copies of the 17-55 f/2.8 IS I had last year. Now it's something I always check for when I get a new lens.

As far as lens creep goes, I had two copies of the 15-85 and both had it. I lived with it though as the second copy I had was sharper than the first.