On Wed, 9 Mar 2005 15:14:32 EST, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
Obviously a small (higher) f stop shows up fine detail that might get blurred
with a shallower depth of field.
This is precisely what is not obvious to me. If the dust is on the front element of the lens yes, it will be more visible at smaller apertures. But we are talking about sensor dust, which is right on the sensor, without a lens to "focus" it. j
Well, I'm not a physicist but it seems to me that at small aperatures a very small cone of light is reaching the sensor, while at large aperatures the cone of light is very broad. The narrow cone is more collimated (like a condenser enlarging lens) and images the dust particles better than the broad cone of light (like a cold light source enlarging lens).
Maybe it's more complicated than this, but this explanation seems to make sense and accords well with practical experience with enlargers as well. I stand ready to be corrected by the graybeard mavens here. ;<)
Regards, Jim
