Luna Pro calibration - part II

[Igor.Burshteyn]

Here is the reference to part I.
http://www.rangefinderforum.com/forums/showthread.php?t=9020
Folks I was wrong when I wrote my LunaPro is off 3-5 stops (don't drink much beer when you meter!). Finally I compared LunaPro measurements to Sekonic L508. So real world data is:
in incindent measurements, LunaPro meters +1EV over Sekonic, quite consistent; LunaPro's reflected measurements from 18% grey card give half stop to full stop over incindent ones.
How it looks now? Can this be adjusted by zero position screw, or still LunaPro requires full calibration? Any experience to share?

 

[phototone]

If I recall correctly the LunaPro should give the same value when reading a grey card using reflected light position, and from grey card position with incident sphere in place aimed at light source. If it doesn't then perhaps your incident sphere has yellowed or aged and is not permitting the correct amount of light through.

While I don't know how to calibrate a LunaPro, I do know that the meter has four adjustment screws in addition to the zero adjustment. These, while not user adjustable from the outside are for calibration of the low and high end of the "LOW" range, and the low and high end of the "HIGH" range. There are no compensating adjustments for the Incident Sphere.