| Author | Message | ||
     Arnold Harris Rating: N/A |
What's wrong with testing a light meter with a second light meter, calibrated by inserting a fresh battery? This is a question, not a statement. I know little about light meters, and perhaps my question reflects naivete. The ones I have used over 35 years are exposure meters built into the Voigtlander Vitessa-T 35mm rangefinders that constitute nearly all the cameras I have owned and operated. These are powered by selenium cells. All but a couple of my 42 Vitessa-Ts have exposure meters that seem to function well. As I CLA and, as necessary, rebuild all these, I expect to test the built-in selenium cell units and their galvanometers against a newer and mountable Voigtlander battery-powered light meter. Unfortunately, the digital scale on the latter device is in f-stops rather than exposure values (EVs) as I am used to. However, the Compur lenses have f-stops imprinted on the bottom and exposure values on the top of the aperature setting rings. So I expect to know with sufficient accuracy whether any of my old selenium cell exposure meters need adjustment or selenium cell replacement. Frankly, I have been surprised to learn that these old selenium cell exposure meters still work at all after emerging from their German factories 50 years ago. But some knowledgeable people I have read think the selenium wafers are affected more by moisture and corrosion than by light. I also understand the selenium cells and their potted connections can be cleaned off with acetone. Has anyone on this forum tried that? In any case, new selenium cell wafers can be ordered in exact sizes and shapes from Magnetron in the UK, and Quality Light Metrics in Los Angeles CA can adjust the unit (the galvanometer, presumably) for old camera owners who can remove their light meters from the camera and ship them to Los Angeles. Arnold Harris Mount Horeb WI |