My one, only, and first (real) 35mm camera is a Minolta SRT 101 dating to 1971-ish. It was apparently ahead of its time in terms of through-the-lens (TTL) metering and even by today’s standards it seems to work pretty damn good as far as I can tell.
That said, there is a small obstacle to getting the light meter running to begin with. The camera is designed to use the obsolete and hard-to-obtain PX625 battery. Of course, the light meter is the only thing that needs the battery, so if you can set up your shots by other means the camera works great. In fact, for a while I was using a light meter app on my smartphone and/or using the Sunny 16 rule as a basis for guesstimating the exposure, and that worked fine enough that I still occasionally forget that the camera even has a built-in light meter. But it’s definitely worth using.
OK, but how? Find some legacy battery from the days before mercury cells were banned? Order from Russia and hope you don’t get scammed? Buy or rig up some sort of adapter to get a modern battery to work in it? Nah. It’s simple. I don’t know about other cameras but a 1.4v #675 hearing aid battery from the grocery store will work just fine for the SRT 101. No adapters. No compensation. Just put the dang thing in and go. Yes, the 675 is smaller than the 625 and you can buy or make a spacer to get it to fit more snugly, but this is unnecessary. It is easy enough to place the battery in the center of the cavity and carefully screw the lid back down, holding it in place good enough that it makes contact and the current can flow.
1.4v is close enough to the original 1.35v that it makes no noticeable difference, in my experience. I’ve heard the modern zinc-air batteries drain faster. I didn’t grow up in the era of mercury batteries so I can’t compare, but a single battery will get you through several, perhaps many, rolls of film, depending on how you meter. I don’t meter constantly. I’ll usually flip the meter on when I start shooting and then just go with it until the lighting situation changes.
junkyard photo 