On Thu, 6 Aug 1998 16:19:21 -0400, "Michael A. Covington" wrote:

>I've just been thinking...
>
>The 100-mm f/2.8 lens on my Carousel projector is a 3-element lens.
>
>I'll be it would be appreciably sharper if I masked it down to f/4, right?
>Brightness is not an issue... I think I'll try it. Has anyone else tried
>this?

Yes, and the brightness loss is a worthwhile trade for the improved
sharpness and DOF - I stuck a thin round piece of black paper
into the rear of a projection lens, with a circle cut in the middle.
This is a reasonable way to improve "El Cheapo" projector lenses.