Odd Focus Plane

[Kayaker72]

Yeah, I noticed that too, sharp bottom left/top right, and blurry bottom left.
That's what you get when you use a Tilt lens like a TS-E.
But it's also what you get when a single element is tilted, or 'decentred'.
Here is a nice write up on the phenomenon.
And you're right, it can happen with a loose element or three. From what I've heard the 15-85 is a bit prone to it, my copy vignettes differently on the left-right sides at 15mm, which is also a sign of decentring. Does yours? Other than that, have you dropped it, or even slightly banged it lately? even worse if the IS was on at the time? and did you use IS for the shot? sometimes the IS elements might not settle to the correct spot when you turn it off.
Another thing to look out for is a worn mount on the lens or the camera, a tiny bit of wear at wide angles can lead to a lot of 'tilt' too.

Dr....I don't have a TS-E, but agree, that is what I am seeing too. Thanks for the link, I'll work on setting up the tests later today.

As for your questions, have always seen more vigetting in the top left corner and to a lesser extent the bottom left. The lens hasn't been dropped recently, to my knowledge. IS was on at the time, I almost always shoot with IS on for the 15-85. I did check for wear, but don't see anything obvious.

This shot while it does show something, probably isn't the best for narrowing down any faults. Have you tried shooting in portrait configuration, then turning the camera 180 degrees and reshooting to see if the fault can be duplicated, top and bottom of image?

Some more test shots needed.

Thanks Steve....I'll give that a try as well. I've only noticed the issue in landscape and not in any of my portrait shots, so it will be interesting to see if it can be replicated.

The phenomena is not consistent at all. For example from the day in Sedona, I only see the issue in 2-3 of over 240 shots. So, an issue with IS or a loose element makes sense to me. A few other examples from that day that were perfectly sharp (to my eye):


Sedona-9428 by kayaker72, on Flickr


Sedona-9268 by kayaker72, on Flickr

Granted, the rest of the day I shot at f/5.6-f/11. I apparently hadn't had enough coffee yet when I took the landscape shot at f/4.5


Thanks for the suggestions....
Brant