Public Service

[kymtman]

I have purchased one of the best classic meters that I have ever owned, a Gossen Luna-Pro. I did not have the

funding to buy an adapter to replace the Mercury batteries. Rather I took the unit apart and inserted a silicon

diode to reduce the voltage to 2.7v from 3.1v from the battery carriage to the + on the circuit board. This unit

is tack on with my Nikon D2X. This is my third one that I have converted with great success. The batteries needed

to replace the mercury batts will be silver oxide 1.55v (2ea). If anyone has a luna pro in need of conversion I

would gladly

do the conversion for you. The service is free if you pay for the parts. My email is rtincher@prtcnet.org

I am retired and need something to do to keep me from going cuckoo.

It takes me about 30 minutes to make the conversion, and it is much better that most of the adapters offered

today, and cost you a lot less for sure. You will be expected to pay shipping both ways. The reason why I posted

to this forum is most of the classic cameras are without correct meters. Merry Christmas!!

Ronald Tincher

[rnt]

Interesting. The forward drop of a silicon diode is .7V. Are you sure you didn't use a germanium diode?

They have the correct forward drop of ~ .4V.

[dan_b.4]

So what parts, specifically, would you need, and can you suggest a place to buy them? (As you can tell, I'm not much on do-it-yourself

electronics!)

[rnt]

Never mind. I see from one of your earlier posts that you're using a shottky diode which has a .1 to .4

forward drop.

[richard_beisigl]

Ron, I have a Luna Pro, and would like to know how much it would cost to convert it.Thanks.

[kymtman]

Gentlemen;

The adapters use two schottky diodes. I use one silicon diode 1n4148 which has a voltage drop of 0 .8 measured

with my digital volt meter with two new LR44s. I bought a bunch for about 15 cents each. I use a piece of foam

to wrap the LR44 batteries to hold them in place. The LR44s are less in diameter then the original Mercury. I

was informed by a friend of mine that his batteries lasted for a little over a year. He used the Energizer batts.

I suppose it depends on the amount of use they get. There is no worry about corrosion with the silver oxide

batts. I live in Kentucky and I don't know how much the post office will charge, not as much as an adapter for

postage both ways, I am sure. My other post where a friend of mine was to do the work has declined, due to his

work load. He is a tv repairman as I once was. If you are satisfied with my work then I would not hesitate to

accept a donation if you feel you should. I am on a limited income.

Thanks guys for your interest

[kymtman]

The drop that I refer to when I measure the voltage is as follows. I use two new batteries and measure across them and the diode and to get the voltage rendered. I divide the dropped voltage with the battery voltage to get the percentage of drop. in most cases the results are 0.8 percent, enough to bring the new voltage between 2.48v and 2.71v. I have two meters (LunaPro) and a Sekonic and my new digital Nikon that measures superbly and my LunaPros are within 1/4 of a stop. Can you ask for more than that with classic equipment?

[BrianS1664879711]

Ron... you're a very generous guy! Keep busy, though, since retirement can be very short if you don't!

[rustys pics]

Years ago I bought the 1.5 volt adaptor sold by Bogen for the Luna Pro. It is still my most accurate meter, more responsive

than the Luna Digital I have, which is starting to freeze up. The Analog Luna keeps on ticking.

[razondetre]

Ron, what we all need is someone to rip out the solar cells from cheap Dollar Store $1. handheld calculators and install them in the selenium cell meters built into cameras (like my Contessa) or handheld meters (like the Zeiss Ikophot or Gossen Pilot) and then calibrate (if necessary). Just haven't had the time to try this type project yet.

 

My father is an old time electronics repair guy and retired now but he spends most of his time rebuilding turntables and feeding cats. No time to rebuild my flashes.

[JDMvW]

I was lucky enough to find a model of the Luna-Pro SBC that uses an ordinary 9-volt battery. Best meter I ever had, including some old Sears rebadged Gossens from the selenium days.