Pentax Spotmeter V Adjustment?

[kq6up]

Anyone know what pot adjusts the Pentax spot's y intercept for the scale? The slope is fine (it seems to be off by the same 2/3 of a stop on the top and the bottom of the scale). It compared well to my Gossen before I adjusted the zero back to the middle of the black dot. The previous owner might have adjusted this as a kludge instead of having it actually calibrated. If this is easily remedied by adjusting a trimmer pot or something, I have already been inside to secure two screws that were rattling around inside the unit. Opening it up is fairly easy now that I know how.

Any suggestions would be appreciated.

Thanks,
Chris Maness

[Jan Becket]

Is this the Zone VI version of the Pentax spot or the generic one? My Zone VI, as adjusted by Calumet, overexposes by 2/3 to one stop, relative to the reading of my Sekonic L-408 when both are pointed at the same 18% gray card. Send it to Quality Light Metric in LA for calibration.

[Regular Rod]

I don't understand. The only adjustment I've ever made on mine is with the little screw above the battery test button to get the needle to bisect the black circle exactly. The exposures seem to be correct. What is the "y intercept"?

RR

[kq6up]

Jan, QLM just uses another spot meter for comparison. If I know what pot/pots to turn, I can adjust it myself. He is a really nice guy and knows his stuff however he does not have a standard luminance source, and that would be the only added value for me to send it in (sans me not figuring out what pot to tweak).

Rod, I am not sure what jargon to use to describe the error/imprecision I am dealing with. I just used a math term to describe it. It is reading high across the whole range as opposed to a non-linear response to light or slope that increases too quickly or too slowly. The y intercept is where the line a graph intersects the y axis.

Thanks,
Chris Maness