Leicameter and Wein cell issue

[Carl E]

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I recently bought a Leicameter to go with my M4, but when I insert a Wein cell (PX 625 replacement) in the battery compartment I have to apply a fair amount of pressure to the battery to get the meter to respond. If not the meter needle behaves erratically and the battery check will not work properly. In fact I have had to put a paper "spacer" on top of the battery before closing he chamber so that the battery is forced all the way in to get the meter to work.

 

Has anyone had similar issues with using Wein cells in their Leiameter?

[Robert J]

Since I had the same problem when using the mercury batteries in my leicameter,I don't believe the problem is restricted to the Wein cell.

[Carl E]

Thanks for the update. It seems I will just have to live with it and be on the lookout for erratic behaviour.

[willwright]

why are you still messing with wein cells? Use the 625a alkaline which is a direct replacement for the old mercury 625...you'll eventually need the meter adjusted to the higher voltage, and you could get an overhaul on it for around $50 at the same time. Weins are 20 years ago!

[Carl E]

I did not want to spend lots of money on re-calibration just now. It would probably be a lot more than 50 USD in Norway where I am based. I may re-calibrate the Leicameter if I need to service it for another reason later on.

[chrism]

675 zinc air hearing aid batteries are much cheaper, and I believe they have characteristics sufficiently similar to the mercury 625 that meters don't need recalibrating (at least this is true for the Olympus OM-1 - I don't have a Leicameter). They are much much cheaper than Weins too.

 

Chris

[cbretteville]

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Carl,

I bought gizmo that let me use std batteries in the Leicameter. Basically the casing from a 625 cell with some electronics added. I'll see if I can't dig up a link and post it.

 

Carl

[cbretteville]

Found it, a CRIS adapter, $32.99

 

http://www.criscam.com/mercury_battery_adapters.php

 

Carl

[masjah]

why are you still messing with wein cells? Use the 625a alkaline which is a direct replacement for the old mercury 625...you'll eventually need the meter adjusted to the higher voltage, and you could get an overhaul on it for around $50 at the same time. Weins are 20 years ago!

 

At the risk of going over old ground for the nth time, it's not just the voltage that's important, but also the discharge characteristic. Early electronics which used mercury cells relied on the fact that their voltage remains pretty constant to the end. Wein cells do this at the same voltage. Silver cells do this, but at too high a voltage. You can either (a) use Wein cells, ( pay for a recalibration to use silver cells, or © use an adapter, which takes a smaller size silver cell, and has a forward biased Schottky diode to provide the necessary voltage drop to what the original mercury cell would have been. Alkaline cells are not really a satisfactory solution because their discharge characteristic is far too "sloping"

[Joop van Heijgen]

Jay (leicajay):

 

 

"In helping my friend secure an MR-4 for his non-metered M's, I've gotten hold of several of them in working/accurate condition and discovered something interesting:

 

Checking the readings at the low, mid and high ends of the brightness range, I have found no variation between the following (voltages tested on a meter):

 

a new (never used) PX625 1.3V Mercury battery

 

a new PX625-A 1.5V Alkaline battery

 

a new MS76 1.55v Silver-Oxide battery in a CRIS MR9 1.3v adaptor

 

a new MS76 1.55v Silver-Oxide battery in a washer-spacer (left over from a Wein cell).

 

I did not have the same results when I tried this with a Leicaflex SL, M5 or CL, all of which required compensation with a 1.5v and then would still not read accurately at both ends of the brightness range.

 

Could it be that the MR-4, made by Metrawatt, has a built-in voltage regulator that nobody knows about? I'm reluctant to open these meters since I don't own them, and wouldn't know what I was looking at if I did. Just curious if anybody else has checked an MR4 with different battery types and found the same thing. I don't mean the readings are close, they're *identical*. BTW for using the MR9 adaptor I would recommend a 386 vs an MS76 because the latter is thicker and pushes the battery door open a little--and those battery doors don't look like they're too strong"

 

http://www.l-camera-forum.com/leica-forum/discus_e/messages/2/50437.html

[Michael Geschlecht]

Hello Everybody,

 

What I have done w/ my 1st version MR (tab out of side not on top) is use a silver 303/357 cell held in place w/ a 12mm split ring w/ the inside spiraled into the center like a watch/clock balance spring (done w/ 2 pair of small needle-nose pliers). After doing that I change the ISO to + 1/2 stop: ISO 100 film becomes ISO 150 or (easier) on the same meter DIN + 1.5 which is do-able because the MR doesn't have click stops for values. On my adjusted meter my now ISO 100 film will give me accurate readings from EV +2 to EV +18 being careful to not use the white portions @ either end of the scale as suggested by Leitz. Something I do w/ all analog meters.

 

I then find the meter matches its performance to a PX625 mercury cell used as a comparator. Double checked with both mercury cell & silver 303/357 w/ a Minolta 101. Since mercury batteries have not been around for years you can tell I have been using it this way for years. BTW the Minolta 101 was one of the World's earlier evaluative metering systems which means that aspect must be defeated in order to do the tests I performed.

 

Best Regards,

 

Michael

[Carl E]

Thanks for all the input

 

I have struggled with my MR-4 and the Wein cell. It seemed that the physical size of the Wein cell does not fit very well with the battery chamber of the Leicameter, so I have had intermittent failures and a seemingly rapid discharge of the battery itself. Today I tried a the modern P625X replacement and the meter now seems to work better than with the Wein cell, plus it seems to give readings that match my other camera. I think I will just let the 1.5 V cell sit in the Leicameter

[Joop van Heijgen]

Thanks for all the input

 

I think I will just let the 1.5 V cell sit in the Leicameter

 

Just curious if anybody else has checked an MR4 with different battery types and found the same thing. I don't mean the readings are close, they're *identical*.