Archived posting to the Leica Users Group, 2001/01/18

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Subject: Re: [Leica] Lunasix lunacy
From: "Mike Durling" <>
Date: Thu, 18 Jan 2001 20:29:24 -0500
References: <>

A long time ago my Luna Pro was reading about a stop high.  I opened it up
and if memory serves me well there are two little calibration screws
(potentiometers) inside.  I don't remember but one may be for the high scale
and one for the low.  There are screws to open the shell up under the
aluminum plate on the back.  I just borrowed a reliable meter from another
photographer and did the adjustment myself.  That was fifteen years ago and
the meter always gives me good exposures.

My Luna Pro's mercury cells are about at the end of their life so I will
probably be looking for a replacement power source too.  Others on this list
have recommended using hearing aide zinc-air batteries.  They are a little
small so you have to use a rubber grommet around them and a copper washer to
make up the height.  They are much cheaper than Wein cells.

Mike D
Williamsburg, VA

- ----- Original Message -----
From: "Peter A. Klein" <>
To: <>
Sent: Thursday, January 18, 2001 2:55 PM
Subject: [Leica] Lunasix lunacy

> My Leicas have no internal meters.  I have an old Gossen Lunasix 3
> (European equivalent the old CdS Luna-Pro, most closely equivalent to
> the current Luna Pro S).  It takes mercury batteries, which are now
> banned in the U.S.  My last mercury cells have run out.
> I tried to use the Bogen adapter that takes silver oxide cells--it was a
> little too big for the battery compartment.  I called Quality Light
> Metric in Los Angeles, who wants about $70 to CLA the meter and
> "recalibrate it to use current (alkaline?) batteries."  A local camera
> repairman wants at least $50 for a similar job.
> So I picked up a pair of "Wein" zinc-air cells, which are supposed to
> replace mercury batteries.  With the Weins, the Lunasix's battery test
> reads just a little *above* the red zone that indicates proper voltage.
> Mercury cells gave a reading right in the middle of the red.  The Weins
> are reading 1.4 volts each on my voltmeter, rather than 1.35 the mercury
> cells are supposed to generate (the reading is with no load, of course).
> And light readings are a little different than before.  The local repair
> guy tested my meter with the Wein cells, and told me it's reading one
> stop high, but consistently.  Fine, so all I need to do is set the film
> speed to half what it actually is.  But he says he can only test down to
> EV 6 at ISO 100 (11 on the meter's low light range, corresponding to
> EV8, or 1/60 at f/2 on 400 speed film).  He also says that no meter test
> device he knows goes much lower than that.  So he claims one can't test
> the accuracy of a meter at common available light levels.  Hmm...
> I've also noticed a small discrepancy between the high and low ranges of
> the meter. 12 on the meter scale is both the highest reading on the low
> range and the lowest reading on the high range. But I've noticed that if
> I take an incident reading, and place myself a sufficient distance from
> a light source to get a 12 on the high range, the reading on the low
> range is usually a bit over 12 (closer to what would be 13 if it were
> not off the scale).  Wein, Wein, why don't you align?   Does anyone know
> if this is caused by the Wein cells' voltage being a little high, or if
> this is a quirk of the Lunasix 3 itself?  If so, which scale should I
> believe?
> With all that's going on, I'm not sure I trust the meter, and I'm not
> sure I want to spend $50 to $70+ on a 30 year-old meter I could only
> sell for $30.  Also, I wonder if the Wein cells will change voltage over
> time, with a change in reading.
> I'm beginning to think I should just buy a new meter like the Luna Pro
> Digital or the Polaris Digital, as testified to in the archives by Jim
> Brick, Kyle Cassidy and others.  OTOH, it's a shame to trash such a good
> meter as the LunaSix 3 if I can get it working reliably without sinking
> a lot of money into it.
> Comments, anyone?
> --Peter Klein
> Seattle, WA

In reply to: Message from "Peter A. Klein" <> ([Leica] Lunasix lunacy)