Originally Posted by daniel~
You're welcome. :-) Well what I'd do is run a mini test: shoot a dozen of pics, rewind the film but leaving leader outside, then use one of my own perfectly-working camera to finish the rest. It's a quick & economical way to get a roll finished and to find out how the new gear performs.
I happened to have one old ISO 100 12exp. print film in my fridge, so I used it. The results: constant underexposure. I checked the combined voltage of the alkalines with a multimeter and it read 2.55V (2x1.275). Quite normal for half-depleted alkalines and it also confirms my initial theory that the light meter needs constant voltage.
The underexposure was fairly serious (more than 1 stop) and clearly visible also in the prints, so I find it possible that the meter might be calibrated even for 1.55V silver-oxide batteries. On the other hand the age of the camera speaks against that, since in the early 1970s silver-oxides were new technology and most meters were still calibrated for mercury batteries.
So, now I will probably activate a pair of zinc-airs and shoot another roll of negative film with them. Fortunately the Rayovac zinc-airs I use seem to last at least 6 months after activation. No need for expensive WeinCells, which won't last much more than a year after activation either. The Duracell zinc-airs usually deplete in 2-3 months due to more efficient -- in this case too efficient! -- air intakes. I will probably take some shots with silver-oxides as well to see the difference.