For my money, the black drop appears to be substantially caused by the
eye's own optical illusion, and is dependant upon the image scale of the
eyepiece (the effect was more pronounced at what experience tells me is
medium magnification and wasn't noticable when the Venus image was very
small (zooming out the Photoshop image greatly) or very large (highly
zoomed in.)


Thank you ! I concur with this. I purposley made hi magnification
images and kept them slightly dark to Verify this effect . In Dayton
Ohio Seeing was Fantastic and the Disc of venus exibited No Black drop
shape that I could image. my pics at :

http://home.woh.rr.com/directoryww/0...itOfVenus.html

Woody AKA (disposable Spambait E-mail)