BetterPhoto Q&A
Category: To Be Categorized

light meters

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August 18, 2000

There are several solutions:
(1) One is what you mentioned; get camera modified for the higher voltage cells. However, if you use alkalines after doing this they have a gradual voltage falloff during their life that will affect metering accuracy. Silver and Mercury cells keep a steady voltage until they are just about ready to drop dead. It is also the most expensive option.

(2) You can get a direct replacement Wein zinc-air cell which has the lower Mercury cell voltage from most large photo stores. These are just under $10 a cell and once you activate them they have a limited life. However, the Wein cell was specifically designed for mercury replacement in cameras and since its size is much bigger than a hearing aid cell, it will last longer.

(3) You can get an adapter ring that allows using readily available 675 zinc-air hearing aid cells which also have the lower Mercury cell voltage. The ring is reusable and the cells relatively inexpensive. These smaller cells will run down faster, and once activated they do have a limited life. A source for the adapter is here:
http://www.olympusguy.com/NewLArt8.htm

(4) Another adapter uses a diode to drop the voltage of a Silver MS76 to that of the Mercury cell. The reusable adapter has the shape and size of the 625 Mercury and is very sturdy metal. The smaller, readily available, Silver MS76 fits inside it. The Silver cells last longest. It is a little more expensive than the adapter ring. This is the option I've used on both my OM-1n and Rollei 35S which also used the 625 Mercury cell. A source for them is here (see the MR-9 battery adapter):
http://www.criscam.com/

Hope this helps you out. The OM-1 is a real workhorse camera body! My 1n just keeps running and running and running.
-- John

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September 02, 2000