Need battery for Canon Ftb: Mallory PX PX-625
I need a 1.3v M20 (#625) battery for my Canon Ftp. Mallory PX-625 and Eveready EPX 625 are listed as replacements. However none of these are mercury batteries and the voltage is usually 1.5 not 1.3.
Does it matter if the battery is not Mercury?
Does it mater if the nominal voltage is 1.5 and not 1.3?
This battery powers the built-in meter.
Why do I use this antique? Well I need to take ultra slow pictures (1 second) from a tripod and using a bulb operated operating button to avoid camera shake.
Nothing newer that I can afford offers these features.
All replies appreciated.