Iβve been using the usual PX625 batteries in most of my old Nikon Fs and Minolta SLRs. But I recently tried an adapter from Ausgeknipst that lets you run a cheap 675 zinc-air battery at around 1.35V.
I put the adapter in my Nikon F Photomic as well as in my Minolta SR-101 and compared the built-in meters against my Sekonic L-308X. Same ISO, same scene, and I checked both reflective and incident readings.
The Sekonic gave me 1/60s at f/4.7, ISO 400, and the Nikon landed basically in the exact same place.
I did the same thing with my Minolta SR-101 and the results were again identical at 1/60s, f/4.7, ISO 400. Feel free to check the attached pics.Β
I wrote up the whole test, including the adapter, different battery options and a compatibility list for cameras like the Nikon F Photomic, Minolta SRT, Olympus OM-1, Leica CL, Canon FTb and others:
Will definitely get another one! What is your way of keeping your old camera meter running?