Strange flare with 5dII. Please check.

Started Feb 12, 2009 | Discussions thread
OP elgeorgio Forum Member • Posts: 59
Image quality test

Since unwanted reflections are a long standing enemy of image contrast I did the following test:

Took two pictures (a lot more actually, 11 pairs to be precise, I just present one pair here). The second was with the camera rotated by 180 degrees. Bellow I post one strip of each one (Sorry for size, 1:1 pixel ratio).
All settings were the same for both shots:
Camera on tripod.
Portrait orientation.
Manual focus with live view (focused only once per picture pair).
Release with remote control during live view (see mirror lockup).
Manual exposure (from exif: f4.5, 1/400, ISO 400, EF24-105L @ 105mm).
Shot in Raw and processed in DPP with default settings.
Exported to TIFF and cropped/combined in CS3.
Exported to jpg with maximum quality.

I had to crop a bit to the left/right to make the images best fit.

Observe how the fairly bright sky affects the image quality when it is towards the bottom of the camera.

There is no motion blur, just degradation of contrast ( I had to even convince myself).
Check the letters on the solar collectors.

Note how the situation reverses as you go from right to left. Top strip is worse at right side, bottom strip is worse at left side (do not forget camera was in portrait orientation). The side that was closer to the bottom side of the camera suffers the most.

The top strip has the effect more obvious because the sky at the right side was brighter.

Also note that this is not extreme shooting conditions; the sky is within dynamic range without any highlights recovery.

Nothing catastrophic but goes to show that even if we do not see bright bars across our pictures, the issue is still there and under specific conditions may be real problem for some; being psychological or practical

Cheers
George
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