Quote Originally Posted by wiltw View Post
I know, with certainty that SOME meters could substitute 1.5v for the original 1.35v battery, and not have a problem.
But SOME meters absolutely cannot simply be compensated for even a constant 0.15v difference simply because the amount of meter error is different at different levels of light being measured! The meter in the Olympus OM-1 is one of these...I know, because I still have a few mercury oxide cells and compared the mercury oxide reading with a 1.5v substitute, and the error was NOT consistent at different light levels.
The Pentax Spotmatic series may all be ok (when they use a bridge circuit with Silver Oxide or alkaline batteries).
The Pentax K1000 series ditto (they use a dual coil galvanometer for similar effect)
But I'd use silver oxide in either myself, e.g. cept when stuck on Sunday, with dead battery and no shops.

The rest probably all need a Shockley diode to drop the Silver ovide 1.5 volts (nominal) to close to 1.33 volts.

Most of the time I remove battery and use sunnyside f/16...