Originally posted by Ontarian50 Earlier references to a "bridging circuit" in Spotmatics making them impervious to battery voltage errors doesn't ring true with me.
The fact is that you're completely wrong, physics is not an opinion....and I've taken DOZENS of rolls of film that prove that. NEVER had a single undersexposure, not even with slide film.
Some "underexposed" shots:
The battery used is a Vart PX625A 0% mercury and lead.
Originally posted by pathdoc Interesting. What are the implications for non-Takumar lenses that lack the aperture-data arm?
Essentially a M42 lens without the aperture blade can be metered just stop down. Just three companies in the M42 era were able to invent a system to meter wide open: Pentax, Fuji and Praktica.
Pentax had the additional blade, Fuji invented an external pin that engaged with a slot in the bodies of high end cameras and the DDR guys used a ingenious electric system with resistances or capacitors that could be read by the body. All these systems are different and the SPF is also incompatible with some M42 lenses like the Soviet Helios.