|
Yes I see the shield in the pic, that should be more then enough to stop stray light. Sure is a curiosity what the cause of the optical effects is that flatfielding cant get rid of.
One final thing, I used to do flatfielding using a floodlight lighting up the white wall of the house, however with the modded camera excess IR light seemed to be causing effects in the flatfield that led to a faint ring like area in the middle of the finished images. I now use a fluro light, and , holding it by hand, illuminate the white wall of the garage with the scope pointing at it. I aim for flats with the histogram roughly in the middle. The fluro light is low in IR light, so only visible light goes into making the flat. Perhaps your focal reducer is passing IR light differently. Might be worth trying that, illuminate somethign white, such as a square of cardboard held in front of the scope with a fluro light and see if that helps. I also tried sky flats with my system but always seemed to get uneven results.
Scott
|