Gossen Luna Pro F

[Ari]

Hi,
My recently acquired Luna Pro F is exhibiting signs of underexposure.
Compared to my benchmark, the Minolta IVf, it is consistently under by 1 2/3 stops.
I have reset the needle, changed the battery, turned the calibrating screw at the back; all to no avail.
Anyone have any tips, something I missed, or useful information?
Thanks

[Steve Hamley]

Do you have the exposure compensation tab set to zero? If there's a red spot showing on the edge of the dial, it should be covered up by the black tab.

Cheers, Steve

[Ari]

Steve,
The EC tab is indeed set to zero; I have to set it to -1 2/3 in order for it to line up with the Minolta reading.
I've read elsewhere that these meters are frequently off by at least one stop, so I guess I'm asking how do I re-calibrate it?
Thanks

[Darin Boville]

If it is consistent why worry?

--Darin

[Sevo]

My Profisix (the immediate predecessor, a.k.a. Lunapro SBC for the metrically challenged) never has been off - if there should be a systematic error that must be particular to the Lunasix F.

If the calibration screw at the back is past its range, you'll either have to live with it, or mail it in to Gossen Germany - they still service all black shell generation Lunasix/Profisix models.

[Ari]

Sevo,
What do you mean by "past its range"?
Thanks

[jwaddison]

I think all the adjusting screw does is zero the needle. There is no "range".

[Ari]

From what I can see on my meter, the adjusting screw moves the needle back and forth about a half stop, even if you keep turning it in the same direction.
If this isn't the norm, somebody please let me know, as that may be the problem.
Thanks

[Darin Boville]

I thought the adjusting screw was just to zero the meter (with no meter reading taken) not to bias the result one way or the other....might not have much "range" to it...

--Darin

[Ari]

I thought the adjusting screw was just to zero the meter (with no meter reading taken) not to bias the result one way or the other....might not have much "range" to it...

--Darin

That's correct; I suppose that the needle on mine is functioning properly.
Now, what to do about the almost 2-stop discrepancy?

[SMBooth]

This may help If your up for recalibrating it yourself.
http://www.graphic-fusion.com/lunapro.htm

[Ari]

Thanks, I'll have a look.

[JoeV]

I've owned a Luna Pro F for several decades, and recently it started having problems with not being able to zero the needle on the scale in bright light. So I shipped it off to Quality Light Metric in Hollywood, Ca. It came back good as new, with a calibration sticker, too. Price was well under $100.

~Joe

[Ari]

Thanks, Joe. Sending it out for repair is a last resort.

[Sevo]

This may help If your up for recalibrating it yourself.
http://www.graphic-fusion.com/lunapro.htm

That won't help, the only thing these have in common is the name. Gossen rather made a mess of its nomenclature. Besides calling all their pro meters Lunapro in the US, they re-used even their European names. The Lunasix F is a Profisix with added flash mode (released after the Mastersix, to pitch something against the flash enabled Autometer IIIF when flash capability moved into the mid price segment). The original Lunasix was the predecessor of the Profisix - a sixties plain electromechanical CdS meter, while the Lunasix F is a eighties digital metering computer disguised behind a pointer instrument.