[surewinlui]

I took the following photo at aperture f22 and noted a circle and a dot in the photo. Both the circle and the dot did not appear in the photo when it was taken at large aperture f1.8.

http://www.dcfever.com/photosharing/view.php?id=693671

I do Mirror lock up and see that there is no dust in the CMOS surface.
Is the black dot caused by dead point in the CMOS.

Please H E L P and comment?

[vicliu]

may be dust

[Obi-Wan]

DUST on CMOS, can be removed by air, or go to CS OR if u don't use f22, it will be ok

[Obi-Wan]

the bright spot may be caused by diffraction (just guess)

[yinlung]

don't brush by CCD brush............. keep it in warm/hot air ...make the humidity low and blow with air