Bert - I hear you, but a "dark" is a dark, is it not? Brian's example dark has a very apparent discontinuation, I'm not sure that you can contribute it to mirror shadow, vignetting or light scatter - it appears too pronounced to me. There is no reason that I know of where a proper dark should display these properties. Aperture fully covered - no light. Vignetting aside in the flat example, (yes, welcome to full frame
) shouldn't the "dark" be consistent across the frame edge to edge? I would have thought so - unless there was pretty severe light leakage when Brian's example dark was exposed.
Brian - what's it like if you take another shot with the lens cap on, covered in a black cloth and sitting in a dark cupboard for 300 seconds?
