Wein cell battery

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carobert@lakeheadu.ca - 20 Jul 2006 01:22 GMT

I have a Canon Ftb-n which I hate to put out to pasture. I purchased
the new Wein cell battery for it and the reading are off by 4 or 5
stops. (I checked it against my light meter and my T-70.) Any ideas on
this. Thanks, ahead of time.

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Chris Loffredo - 20 Jul 2006 09:13 GMT

> I have a Canon Ftb-n which I hate to put out to pasture. I purchased
> the new Wein cell battery for it and the reading are off by 4 or 5
> stops. (I checked it against my light meter and my T-70.) Any ideas on
> this. Thanks, ahead of time.

Could the battery be defective or discharged?

You did remove the air-hole covering sticker?

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carobert@lakeheadu.ca - 21 Jul 2006 01:17 GMT

Yes I removed the sticker. I will try to see if it is out by a constant
amount and then I could adjust my ASA to compensate. Either that that
or try another Wein cell; though I understand they don't last very
long.( I have only had this for a year and have hardly used the
camera.)

> > I have a Canon Ftb-n which I hate to put out to pasture. I purchased
> > the new Wein cell battery for it and the reading are off by 4 or 5
[quoted text clipped - 4 lines]
>
> You did remove the air-hole covering sticker?

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Chris Loffredo - 21 Jul 2006 01:29 GMT

> Yes I removed the sticker. I will try to see if it is out by a constant
> amount and then I could adjust my ASA to compensate. Either that that
> or try another Wein cell; though I understand they don't last very
> long.( I have only had this for a year and have hardly used the
> camera.)

That is the disadvantage of Wein cells; they only last a few months (3-5
in my experience), even if the camera is never used. And they are not cheap.

You could buy one of the adapters made to take silver cells, which lower
the voltage (they cost less than 2 Wein cells), try to fit a silver cell
directly into your camera and see what the difference is, or even try an
alkaline cell and measure the difference fairly often (as it runs down);
different meters react very differently to the slight voltage
differences involved - in some cases the differences are negligible.

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Norm Fleming - 21 Jul 2006 16:58 GMT

>> Yes I removed the sticker. I will try to see if it is out by a constant
>> amount and then I could adjust my ASA to compensate. Either that that
[quoted text clipped - 5 lines]
> in my experience), even if the camera is never used. And they are not
> cheap.

You can use hearing aid zinc/air batteries which are very cheap. The 675
size fits exactly the battery chamber of old cameras taking 675 mercury
batteries. They can be easily modfied to fit the larger 625 battery slots
by fitting a rubber washer or a slice of lab tubing or anything else to take
up the space. True, they don't last long but they are so cheap it doesn't
matter. You can prolong the life by removing from the camera when not in use
and taping over the air holes. I have used these for some time in an old
Canon FTb-n (same camera as the original poster). The readings are spot on
with a hand held meter, and the exposures are right on the button..

I have found that for this camera, the silver cell alternative suggested
below just does not work. The meter becomes erratic and is not simply off
by a fixed number of stops.

If you try and estimate exposures in all conditions (natural light, not
studio) by the sunny 16, and keep checking with a meter, you will gradually
become quite accurate without needing a meter, except in very low light.

Cheers

NF

> You could buy one of the adapters made to take silver cells, which lower
> the voltage (they cost less than 2 Wein cells), try to fit a silver cell
> directly into your camera and see what the difference is, or even try an
> alkaline cell and measure the difference fairly often (as it runs down);
> different meters react very differently to the slight voltage differences
> involved - in some cases the differences are negligible.

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Chris Loffredo - 21 Jul 2006 17:52 GMT

> You can use hearing aid zinc/air batteries which are very cheap. The 675
> size fits exactly the battery chamber of old cameras taking 675 mercury
[quoted text clipped - 9 lines]
> below just does not work. The meter becomes erratic and is not simply off
> by a fixed number of stops.

I'll certainly look into the 675 type cells you suggested.
Though the devloting-adapter for silver cells is probably more
competitive, at least in the long run.

I don't understand why a silver cell caused problems in your case - at
least with a devolting-adapter or a re-adjustment of the meter, they
should work perfectly as they deliver constant voltage (practically)
throughout their lives.

I've used the following 625 mercury cell alternatives successfully:

Photomic FTn for Nikon F; 2 alkaline cells, meter readjusted, gives
acceptable results throughout battery life.

Exakamat meter prism for Exakta Varex; 1 alkaline cell, meter
readjusted, gives acceptable results throughout battery life.

Gossen Lunasix 3 hand held meter; 2 alkaline cells, meter readjusted,
gives acceptable results throughout battery life.

Leicaflex SL; 1 silver cell in devolting-adapter, meter not readjusted,
accurate in all situations.

TTL prism for Kiev 60; 3(?) silver cells with spacers, meter readjusted,
gives accurate results throughout battery life.

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Bob Hickey - 24 Sep 2006 04:30 GMT

it exactly right. It only reads for the rectangle inside, which is like a
wide spot meter,which makes no sense. Every camera has a different metering
pattern, and I found it best to just use a hand held meter for all and not
worry too much about finding the right battery. Bob Hickey

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