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

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Subject: [Leica] Lunasix lunacy
From: "Peter A. Klein" <>
Date: Thu, 18 Jan 2001 11:55:06 -0800

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

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

Replies: Reply from "Mike Durling" <> (Re: [Leica] Lunasix lunacy)
Reply from Randy Holst <> (Re: [Leica] Lunasix lunacy)
Reply from Rimrock Foundation <> (Re: [Leica] Lunasix lunacy)