venchka said:
EDIT TO ADD: There is no mention in any of the literature that the Canon QL17 GIII has any kind of voltage regulation. The only Canon camera that I know for a fact has this feature is the Canon EF SLR. If you can prove me wrong I will use alkaline batteries in my QL17.
There's no regulation. I think I posted the simplified schematic with my re-calibration project. If anybody wants I can post it again. I've had it looked over by a couple hardcore electronics geeks and all of us agree that it's a very simple series circuit.
The schematic looks so confusing because there's all of the stuff in there for the Canolite flash, but if you take that out and follow the path for current, it's really the battery, the meter, the light-sensitive resistor cell, the resistor of the speed and aperture dials, and the calibration potentiometer (sp?) which is just a variable resistor.
I forget the exact numbers, but there's something like a 15% error with the newer battery. It makes the whole circuit a bit "hotter", more meter movement for a given luminance, thus a tendency to underexpose.
Using just the calibration potentiometer I was able to get within a half stop or so, calibrating for ISO 1600 film at the most sensitive end of the scale, and for the new battery. By rotating the meter itself to do a true "two-point" calibration, I was able to get the thing very close, both at the dim and bright ends of the scale. This was quite a project, but it did turn out quite well.
🙂