I have been shooting panos for a few weeks now. In about a third of the room shots of the ceiling, when the pano is completed, will have either a lighter or darker circle where the ceiling shot was stitched in.
I've tried altering the exposure in several different ways but I haven't been able to get a grip on exactly why this problem happens. Consequently, my exposure solution is not solving the problem. I'm shooting the rooms with a Canon 20D w/Sigma 8mm. Usually I "Blend" the exposure meter readings and pick a level close to the that needed for the shadowed areas in the room.
Anyway, any suggestions on consistenly avoiding the ceiling ring either through exposure manipulation or specific processing techniques?
Your input would be greatly appreciated.