Meter calibration Re: Leica CL Metering

[Chris Fortunko <fortunko@boulder.nist.gov>]

LUGs,

I recently reported on my experiences with calibrating light meters in Leitz
cameras. I find that the use of the gray card can lead to errors unless the
card is very large and focal length is long.

My preferred method is now based on the use of a good lightbox, like the one
you would use to view high-quality slides. I then use my M6 meter and 90mm
lens as the reference. The same lens is used on the camera to be calibrated.

I do not own a CL, but have heard that the original meter cells were not of
the highest quality. Personally, I like CdS meters. Too bad that the mercury
cells are no longer universally available.

Have a great X-mas and don't forget to use your Leicas,

Chris
At 03:27 PM 12/24/96 -0500, you wrote:
>The meter in the CL is very sensitive. 
>
>When I first got mine, and even now if I haven't used it for a long while,
>the meter takes some getting used to. 
>
>To see if the meter is out of calibration try the folowing:
>
>With either the 90 or 40mm lens meter a grey card covering the full imaging
>area at some ISO and note the readings. Now with the same lighting, use a
>trusted hand held meter and meter the same card. The readings should be the
>same. If not, note the difference.
>
>Since the camera is about 20+ years old, a metering circuit needing a CLA
>should not be a concern. Even a meter that is sticky is no great concern.
>You may want to contact Leica for a CLA estimate (I think mine was about
>$250 several years ago). Use it as a bargaining tool possibly to adjust the
>price. For those I have spoken to about this camera, I tell all that figure
>a CLA in the price. These cameras seem to be treated with more care than
>many others, but also seem to have been less used. This also means most are
>ready for a CLA.
>
>The area metered by the CL is not well defined in the manual, but does not
>seem to be bottom weighted and reads about 12% of the lens coverage
>principally centered about the center with less coverage to the left and
>right. Because of this shape, it seems to read (and change readings) more
>akin to a reading of less coverage. Also, the meter which reads underexposed
>when the needle is above the 'correct exposure' notch is somewhat
>disconcerting at first since this condition is opposite of most other
>metering systems.
>
>When I contacted Leica re: the 625 issue, I was told the metering would not
>be affected by the small difference in voltage. I did a quick comparison
>with my camera and found less than about 1/6th stop. Leica did tell me they
>could recalibrate the circuit. On my next CLA, I'll have it done to use the
>alkaline 625 since my other equip is being recalibrated for this standard
>voltage.
>
>Hope this addresses your concerns. The camera and its lenses are for me
>about as good as it gets since in 35mm, I use slightly wide angle to short
>telephoto focal lengths. The body is substantially smaller than the M series
>and with the 40mm attached is one mighty, great, hi quality and long termed
>systems made. Good luck.
>
>
>
>>
>Brian Levy, J.D.
>Agincourt Ont.
>dlevy@worldy.com
>
>
>