Wein cell size question

[colyn]

Anybody know the size of the zinc air cell that is used in the MRB400 wein cell?

This is the replacement battery for the Pentax Spotmatic cameras in place of the original mercury cell..

 

[titrisol]

Why not use a normal silver oxide battery?
Spotmatics have a Wheatstone bridge type meter so the voltage difference makes no difference
I got the information a few years back from here: http://tech.groups.yahoo.com/group/Spotmatic/files/
but had been using silver cells since the 80s because they were cheaper and the pictures came out perfectly
After becoming more picky I have checked mine with a 392 cell against a Nikon FE and is well between 1/2 stop

 

[kuzano]

They should...

They should...

The packaging on the MRB400 lists five Spotmatics served by that battery.

I get about a year out of Wein Cells (different number) for my Olympus OM-1. Part of increasing the life span is to take the battery out of the camera when not using it for extended periods and taping the air hole shut to stop the chemical reaction.

 

[colyn]

Why not use a normal silver oxide battery?

I tried this but got over a stop difference in exposure. The camera is accurate with the wein cell. Since I have the plastic wein cell spacer I'd like to buy the packages of zinc-air cells for easy replacement when one goes dead.

Spotmatics have a Wheatstone bridge type meter so the voltage difference makes no difference

This has been proven to be false in some cases. My OM-1 is off with silver cells unless I use the adapter with the Schottky diode to reduce voltage.

A full stop off on exposure won't in most cases affect the outcome when using negative film but will affect proper slide film exposure..

 

[colyn]

The packaging on the MRB400 lists five Spotmatics served by that battery.

Most of the Spotmatics use the MRB400. The Spotmatic F uses silver cells.

I get about a year out of Wein Cells (different number) for my Olympus OM-1. Part of increasing the life span is to take the battery out of the camera when not using it for extended periods and taping the air hole shut to stop the chemical reaction.

What I want to do is buy the package of zinc-air cells so when one dies I can replace it with a new one...not a new wein cell. I need to know which size zinc-air cell was used in the wein cell..

 

[newspaperguy]

colyn -

Your OM-1 does NOT have a Wheatstone bridge-type meter. As you've seen, it will not compensate for the higher voltage.

Like you said, the adapter, or have John H. rewire it. I did, and gave away my W-cell. I think it used the hearing aid size... came five to a card.