I just tried grinding my own GG the other day and have a question for those who may have gone this route before. I used the 5 and 3 micron Aluminum Oxide "dust" from Willmann-Bell and went at it for quite a while - I think my hands will never feel the same agin! I spent about an hour and a half on it in total.
The glass looks extremely smooth and is more fine than any GG I have used before. However, when I compare it with my other GG's (a B&J and whatever is on my Gundlach), it isn't as completely opaque as the others. Of course, it is also finer and smoother. Now, when the camera is focused, it doesn't seem to make a difference, but when it is defocused, there is a hot spot in the center and I can see an outline of the lens aperture.
My question is simply this: should a finely ground glass be totally opaque or will will it be more translucent than one which is roughly ground by comparison? Do I need to go at longer with the 5 micron dust perhaps, or is this as opaque as it's gonna get?
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