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Mug
Tinkerer
Username: Mug
Post Number: 1
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 25, 2009 - 04:03 am: | 
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Did anyone know how to (re)calibrate the Gossen Lunalite lightmeter ? The are three potmeters inside R12, R18 and R19.
The deviation is not liniear so move the ASA knob is not the solution (its about 1 small EV)
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Glenn
Tinkerer
Username: Glenn
Post Number: 708
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 25, 2009 - 03:55 pm: |
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From distant memory the pots are for battery voltage and high/low range cut off/change point. Sadly I cannot recall where I found this information on the web. I need my meters calibrated to traceable standards, so did not bookmark, but a quick twiddle with a screwdriver will soon set you straight as to the function of each pot.
However as I have stated before on this forum, to accurately re-calibrate the meter you must have a known standard to compare it with. To do anything else will have you chasing your tail and getting nowhere! |
Mug
Tinkerer
Username: Mug
Post Number: 2
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 26, 2009 - 09:52 am: |
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I have an recent & good Sekonic meter to compare. There is no battery check knob, so a pot for this not needed. I can measure the resistance values of the pots (if I want back to the original settings). And just find out by trial and error, where is what potmeter for. But if anyone already did such experiment, I could be get faster good results. |
Mug
Tinkerer
Username: Mug
Post Number: 3
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 29, 2009 - 03:50 am: |
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These are my values: Before re-calibrate:
R12 : 2k9 Ohm
R18 : 290 Ohm
R19: 4k4 Ohm
I see no difference in when I change R12 (function of this pot ?)
Calibrate Low light: R19 , Calibrate High light: R18
After calibration:
R12 : 2k9 Ohm
R18 : 460 Ohm
R19: 5k5 Ohm
My low level 'test' light was: 1 sec 1.4
My high level 'test' light (cloudy daylight) was: 1/125 sec F16 |
