Quote Originally Posted by Woolliscroft
This really is not the problem people think it is. Just put in modern 1.5v batteries and set the exposure bias or film speed control to over expose by two thirds of a stop. End of problem.

That could work to some degree David, the problem I understand is that the Canon EF is powered by two 1.35 volt Mercury Oxide PX 625 batteries , 1.5 volt silver oxide ones don't produce the power in the same way, looking at a graph comparing the power output responses they are very different,and would probably produce inconsistent exposures, I researched this recently when the battery of my Canon FTb Packed up. I found the best alternative is to use the PX 625 Zinc Air Wein Cells they don't last as long as the old Mercury Cells, but I have been using them for several months and they seem O.K