Old light meter quandary?

Bill wrs1145

Bill wrs1145

A native Texan
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Nov 12, 2022
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Does the vintage Gossen Luna Pro use: an adapter w/ 2 LR44 batteries, or 2 EPX625G batteries (w/ no adapter)?

Thanks,
Bill
 
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If you can get the adapter that Gossen made that lowers the voltage of the silver oxide batteries to match that of the 1.35v Mercury batteries the meter was designed for, then use that. Do not use LR44 (Alkaline) batteries; you MUST use SR44 (Silver Oxide. Also S76 or 357 work too) batteries.

Alkalines do not keep a stable voltage; it constantly drops as the batteries are used. The Luna Pro does not have built in voltage compensation, so the batteries must deliver 1.35v each (total of 2.7v) at all times or the meter will not be accurate. For this reason, the EPX625G will not work on this meter. The starting voltage (1.5v) is too high and they will constantly drop as they are used, so the meter will never give consistent readings.
 
This is one of the reasons why I finally got my Sekonic L-308 that eats one AA, and takes a very long time to do so ;)

All the classic meters are very nice, don't get me wrong, but that one "just works" does incident, reflective and (should I ever get the desire) flash metering too for a decent price new and my pretty blue 60th anniversary model was even less used.
 
I had several meters converted and calibrated by Quality Light Metric in Hollywood but the owner retired a few years ago and I’m not aware of anyone repairing meters and converting them now.

Anyone know of a light meter repair and conversion service.

George at QLM rebuilt my Weston Ranger 9, Luna Pro, Weston Master V and 3 Leica MR meters. They all take modern batteries now with the exception of the Master V which is a selenium cell. In the Master V he re-magnetized the galvanometer, replaced the cell and the low/high range grid and calibrated it. The all work like new now.

Anyone else doing this? I have one more Ranger 9 I’d like to get calibrated.
 
I think it is sufficient to drop down the voltage with a Schotky diode. However, repairing a meter is far more complicated.
 
Look up KANTO or C.R.I.S MR-9 adapters. I just bought two for my Gossen meter, and they cost me more than the meter did, but should be good for the life of the meter and more. There are also Wein cells, which are also acceptable but not as long lasting as the silver oxide batteries that the adapters use, so the cost adds up eventually.
 
I've used the MR-9 adapters with good results too, but now only in those cameras that take a PX-13/PX-625 original battery. My vintage meters turned over about a dozen or so years ago ... All my current meters use AAA, AA, or CR123 batteries.

G
 
I've got the MR-9 adapters. The only question I have is my online source sells only SR44SW batteries. Will they be acceptable?

Many thanks, guys,
Bill
 
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