Sensor Dirt Advice

Started Mar 10, 2014 | Discussions thread
OP jamesbm Regular Member • Posts: 182
Re: Sensor Dirt Advice

hotdog321 wrote:

This doesn't look like dust or dirt or oil to me. I'm willing to be corrected, but it is much too big and diffuse. Are you using a filter? Could be some strange interference pattern. I would check the lens against a blue sky again rather than a white wall--it might still be there.

Thanks everyone for the advice and the previous image was indeed a crop.

I actually wondered if it was some sort of interference because initially I was using a polarising filter when I spotted the problem and I noticed some very strange looking digitised artefacts in Lightroom, besides the "horse shoe". These amounted to some rather un-smooth gradation across dark blue skies and a lot more noise than normal.

However the problems persisted without the filter. For example the area of sky in the attached image almost looks like hieroglyphics. It is exaggerated by compression and conversion to JPEG, but there are still a lot of artifacts in the original in the sky portion.
I tried a few sky shots this morning and I can't see anything after the air blast, plus a wall shot at f16 and 5s+ showed nothing. Hope to have some time to get out again later..

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