1500 or 1000?

[d4v1dz33]

would 1000 grit ground glass be better for a Static gg or would 1500 grit ground glass be better?

alliteration would be fine

[d4v1dz33]

http://www.optosigma.com/miva/mercha...+%26+Apertures

which one would you buy?

[khmuse]

I am going to go out on a limb here and assume that you are asking about the application of a focus screen (ground glass) in an adapter application.

The question of better is subjective and is really a matter of well chosen compromise. What you are balancing is two divergent requirements. One is the desire for a fine grain surface (to allow for increased resolution) the other is the behavior as a focus screen. If you go too coarse (lower numeric grit size) the screen will have obvious optical grain, if you go to fine (higher numeric grit size) there will be a tendency toward having a center hot spot.

You will need to consider the trade offs and what is most important in your application.

[d4v1dz33]

what do you mean by having a hot spot?

[funkbomb]

Hot spot/vignetting is when the image is brighter in the center and then drops off to a darker image as you go outward towards the corners. This isn't caused by grain though.

What you're really trading off is if you have too fine grain, the aerial image (non-diffused) will show through, cancelling out the DOF effect. In my experience the 1500 grit Optosigma glass is too fine, however the 1000 is too course. I would use the 1000 grit before the 1500 grit, but only in a non-static adapter situation.