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Eclair Cameras: Re-marking an ACL Ground Glass for Super-16

I just answered an e-mail regarding alignment of Super-16 markings on an ACL ground glass. I thought it a useful enough question to pass on. Mark.

Q: How much coverage should one expect from a s16 modified ACL? I have recentered the viewfinder adapter and now the image is nice and centered. However, I can only see roughly half of the additional s16 frame space. Is this just the nature of the conversion?

A: The S-16 markings on the ground glass need to be made in exactly the right place, so that the markings line up with a little convex lens that is glued onto the whole ground glass prism assembly.

You can't assume that if you line up the new markings dead center with the old, that this will necessarily work. In fact, I think that models with the built-in light meter place this lens in a slightly different spot than those without (if memory serves me correctly). So there isn't an exact rule-of-thumb about where to place the new markings.

In the HD-144 kit I include a "S-16 markings" letraset rub-on so that your tech can experiment beforehand with where to place the new markings before having the etching done, to make sure the markings are positioned correctly to be in perfect alignment with this convex lens. Otherwise the edge of the image will indeed be cut off --- the convex lens is just exactly the right length for S-16 (by chance). I once had the S-16 markings put in an incorrect spot on an ACL ground glass prism assembly, so I had to soak the prism in acetone, remove the little lens, realign it by scotch-taping it in place and experimenting to find where it needed to be for the new markings, and then re-attaching it with glue that's used to bond glass (the kind that is activated by exposure to sunlight). Very, very painstaking work --- much better to have the markings etched in the right place to begin with. Also, with another ground glass assembly that I tried this with, the little lens wouldn't come off even with acetone soaking.

(no, acetone didn't seem to affect the mirrored surface as far as I could tell).

This email was sent to: elroro@propagandaindustries.org

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