Originally Posted by
Randy
I had a bunch of Series 7 filter adapters and had a +3 close-up filter in that size, so I just made a lens out of the +3 filter and a stack of about 5-6 of the adapters (screwed together makes a black tube of about 30mm in length) , mounting the lens at the rear of the tube and making an aperture out of black construction paper, and mounting that at the front of the tube...kind of like an unscientific attempt at copying a Wollaston Meniscus lens (concave side of the close-up filter facing the subject)
Anyway, wide open it is about f/7 but is very soft, so the aperture I made comes out to about f/16 - still soft'ish but doesn't create a lot of "glow" in the image. The aperture is about 20mm in front of the glass - guess I should experiment by moving it closer to see how that affects the image quality - just haven't gotten around to it.
Note - since the filter adapters are 55mm, I purchased a 77mm-55mm step down ring and used that to make my mounting flange - just drilled three holes in it for the screws to mount it to my wooden lens-board.
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