A gentleman brought in a rather ancient camera today. Seems it has a view finder that looks down into the camera. Only problem is, he has to physically pick the lens out of the holder and increase the distance about 1/4" to obtain a clear view.
Figuring I needed to decrease the focal length of the lens, I added various powers until he said "that's perfect!" Consequently, I need a lens that is +1.50 stronger than the one currently in the camera's viewfinder. It is the form of the lens that may prove troublesome, however...
The lens currently has a power of +12.50 diopters. I need to increase it to +14.00. The lens is 27mm (I'll need a 28mm lens, to properly edge it, however) in diameter and has an ocular curve of +2.50 and a base curve of +12.50.
Oddly enough, if I compare the lens clock readings to the actual power of the lens, the result is that the index of the lens must be around 1.44, hmmmm. I'm guessing that my clock readings must be slightly off and the lens is actually CR-39 (however, he bought the camera used over 20 years ago... the lens is decidedly not glass).
Anyone out there able to make a lens to the specifications I've provided???
Thanks,
Pete
PS- The gentleman is leaving the country on Oct. 1st, and would ideally like to take his revamped camera with him...
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