I was at a cousin's wedding this weekend, using my K7 with my DA* 16-50 lens. For a time (meaning it wasn't consistent), when I'd go outside to shoot some photos of the groups, I noticed a "soft" spot in my photos...kind of like a smudge, but it wouldn't happen when I was inside. It'd show when the light was in front or behind me, so I didn't think it was the sun...maybe humidity? Its always in the same place on the images...just right of center, towards the top. Its kind of like a little smoke. Maybe its my settings? I'm sure its user error, but what am I doing? I've attached an example. I took this at ISO 400, f/9 1/125.
I appreciate your help, and suggestions.