I bought a basic Spherometer a few years ago in an attempt to work out the refractive index of the simple meniscus lenses used in the Puyo Anachromratique Objectif d'Artiste - with some success!
I am not happy about using a single instrument for measurement, so bought another, this time Vintage, Spherometer recently. Whilst the first Spherometer was very basic - fine screw threads and vernier scales - this one has dial display, gears and can measure both -ve and +ve instantly. Works well and has, apparently, a calibration lever at the side.
I would very much like to hear from anyone who has experience of this all-american product made W.H.Reisner of Hagerstown, MD.
In particular:
- Does the number stamped on the back represent serial number or is it a calibration number. Mine is 159.
- What does the inner ring of numerals mean? The "hour" hand moves when I zero set the "minute" pointer on plane glass.
- Do the measurements/readings represent metric or imperial measure which have to be incorporated into the usual formula. Or was it supplied with a table which "turned" the direct reading into a radius.
I must say that it is delightful example of american fine engineering!
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