Strange vignette

<p class="MsoNormal"]Could someone tell me what&rsquo;s going on here?<span> The lens is the 24-105 at 24mm on a 5DMII.<span> I expected vignette in the corners. But what
is the blue in the upper corners?<span> (ISO 400<span> 1/80 at f8.0 and EV of +1)<span> I took the photo down our drive to record the
major snow fall.<span> The second picture is a
crop of the upper right corner.<span> Oh,
there was definitely no blue sky showing.



<p class="MsoNormal"]http://roffee.org/dump/wiwiredblue400.jpg
<p class="MsoNormal"]http://roffee.org/dump/wiwiredbluecrop400.jpg
<p class="MsoNormal"]Thanks
<p class="MsoNormal"]Larry

@TheRoff...


Please have a look at the following url, it seems that there are others out there with thesame issue. Some have submitted the lens to Canon for further analysis while others cranked up the ISO and stepped down a few to correct.


http://photo.net/canon-eos-digital-camera-forum/00Djmn


I've got the same lens, however mounted on a APS-C body.


Sorry, not sure what else I can say...[:$]

Perhaps the culprit is a UV filter? I don't know that I get this much vignetting on my 24-70 at 2.8. I suspect a UV filter because the vignetting is not gradual, but is very strong in the very-most corner. I expect vignetting to seem stronger with broad areas without much tonal variation (like the arizona blue sky), but with detail like this it is unusual to notice.