Quote Originally Posted by monochromeimages View Post
As far as I know this camera uses a moving needle type meter similar to my Canon F1 (first version). If so I have found a silver oxide battery is fine, the increased voltage just causes it to show a bit 'more light' than there actually is. Setting the ISO to half the actual ISO of the film compensates and gives correct exposures. The same also worked for my Canonet QL17 GIII. I'd be surprised if it doesn't work for you.
The Olympus OM-1 has a needle, too, which one centers in a permanently positioned scale. Its needle swings to one side when power is off. I have conducted direct test of Mercury Oxide vs. alkaline, and have found that the amount of error depends not only upon the actual voltage of the alkaline cell (which varies throughout its lifetime), but is also dependent upon the levels of light being metered, so it is impossible to compensate simply.

I have heard that if a meter needle is centered in a permanently positioned scale AND its meter needle stays centered when power is off, it uses a Wheatstone bridge circuit and is not subject to devialtions caused by different voltage (alkaline cell).