Film vs. Digital... Die, Die, Die! (was: VCF suggestions...

I don't dispute there were electronic cameras going back about 40 years. But fully mechnnical ones exist too. There have even been automatic exposure cameras that don't use a battery... (Contact me off list if you want to know about lock-needle mechanisms and a strange camera with a pneumatically-timed shutter). Most electronic cameras need either 3V or 6V. Some of the later ones with motors use AA or AAA cells, the ones that just use the battery for the meter and chutter control often use silver oxide batteries. AFAIK Mercury cells are no longer made :-( Some older cameras had a fairly simple exposure meter circuit that depended on a constant and known battery voltage (which was the case with a mercury battery). Put a modern alkaline cell in there and you get the wrong exposure. Others used a bridge circuit, with the correct exposure being the balance point of the bridge. These are independant of battery voltage [1] so it's relatively easy to keep them going now. [1] Well some of these cameras had the meter scaled either side of the balance point for 1 stop over/under exposure. This won't be accurate if you use a non-mercury battery, but there's a trivial and obvious workaround. Pentax (idiots!) made a camera with a bridge circuit where the correct exposure was just off balance. The official reasone was so that if the battery was dead you didn't get the pointer on the correct-exposure mark. But of course this thing depends on the right battery voltage. More modern electronic cameras tend to include voltage regulator circuits anyway. -tony