Tech Question, re Nikon FTN CdS Cell Resistance Measurements

[F4U]

Ive got 2 FTN Finders here, both working but both have gone non-linear. They'll both read perfect in the mid ranges. But as soon as I throw a test wall at it down at 1/8 sec and f/2.8 (ASA 200), It's off by a stop or more, tested against my Sekonic 308. On the other end if if throw a 1/250 or 500 f/11 at it, It's off a stop and a half at that end. The typical first suspicion is that one of the 2 cells has gone sour. Since they're wired in parallel, I'm going to have to de-solder one leg on all 4 cells and set up a test light source and use my multimeter to find any 2 that match the best. Logical. Test each one with the same light source, and repeat with no light. But I don't know what the ohmeter readings are supposed to be on these cells. I thought about going on Digikey and studying data sheet on CdS cells to get an idea. But these Nikon cells may very well have a built-in neutral density filter or a lens. Sure would be nice to know the official Nikon resistance data on these cells Thank you.

 

[Bill Burk]

I’d pick up a couple parts FTN finders, that way you get them as they came from the factory. I put a generic cds in a Pentax finder and can’t get low readings to work. But parts bodies give me good cells almost all the time.