Camera Batteries

batteries are not easy. So now figuring out which battery goes with which camera and which charger can sometimes be confusing. Maybe all of the time. These notes are intended to throw some light on this problem.

Battery and camera development proceeded together in lock step. For a century cameras were purely mechanical and batteries were irrelevant. The first need for electricity was for light metering. Canon’s Model 7 introduced in September of 1961 used selenium photocells to power a calibrated meter. Canon’s first battery arrived with the Model 7S

in April of 1965. This camera a CdS (Cadmium sulfide) cell which varied in resistance depending on the amount of light falling on it. To function as a light meter it required a source of electricity.

The mercury battery was known in the 19th century but was not developed until 1942 for wartime miniature devices. By 1965 it was available as a commonly used button cell. It most valuable feature was an almost constant voltage of 1.35 volts during its useful life. It was used in several models till about the end of the “F” series.

The Canonflex series did not require batteries. They all used clip-on selenium meters except the the Canonflex RM which used a built-in selenium meter. No batteries in the bunch.

It was with the AE-1, introduced in April of 1976, that Canon embraced batteries for their cameras. The AE-1, and all of the “A” series, used electrical circuitry to control exposure and shutter timing and operation. This required more power than could be obtained from a button cell.

Prior to the 1960’s the most common batteries were Zinc-Carbon based. The problem with them was that they did not have a great service life. They simply did not provide sufficient power for many uses. Research in the 1930’s led to development for silver oxide batteries which had good power characteristics and shelf life but they were expensive to produce and they were mainly relegated to watches and hearing aids.

In the 1960’s a new type of battery was introduced to the market that we commonly call an “alkaline” battery. These have 3 to five times the power capacity of zinc-carbon batteries, better shelf life and are much more ecologically acceptable.

Because alkaline batteries decrease in voltage as they are used they are avoided in light metering circuits where they could affect meter readings. The battery called for in the AE-1 User Manual was a 6 volt silver oxide battery which had good energy density and had a constant voltage during their lifetime.

Later it became common for people to put alkaline batteries in their AE-1’s and rely on the films exposure latitude to handle any exposure effects. But that is not really encouraged, especially with color film.

Accessories such as the Power Winder A of the Speedlite 155A used alkaline AA cells.

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