finnegan Posted May 30, 2015 Share Posted May 30, 2015 <p>From a post somewhere here I found a recommended replacement for a Pentax Spotmeter Mercury battery. I just got an old but almost new-in-box Honeywell Pentax Spotmeter. I found a manual for it which has a 1.3 Volt Mercury listed and a 9 volt dry battery, the latter from what I know is a rectangular one, where that goes I don't know yet.<br /> The post recommended a WineCell battery to replace the Mercury. The one they have is 1.35 volts, not 1.3.<br /> 1.35 is the spec listed for the one replacement they have for a mercury in a Pentax 1/21 Spotmeter, not a Honeywell Pentax Spotmeter. I'm hoping they are the same or use the same batteries.</p> <p>If so, the question remains: will a non-mercury 1.35 Volt work for the original mercury: 1.30 Volt.<br /> Any idea about this arcane point - but necessary for me.<br /> Thanks.</p> Link to comment Share on other sites More sharing options...
sarah_fox Posted May 30, 2015 Share Posted May 30, 2015 <p>A mercury battery is actually 1.35 volts, so yes, the Wein cell battery will work.</p> <p>I don't have an intimate knowledge of the Pentax spot meter, but I am quite familiar with the venerable Gossen Luna Pro and Luna Six meters, both of which were designed for mercury cells. In my experience, these meters, which are considered among the most stable and accurate of their kind, are almost all inaccurate without re-calibration, even when running the old mercury cells (which can still be found). I'm not talking about fractions of stops of errors, but rather whole stops -- even several stops. I would be stunned if the Pentax meters were more stable and accurate without periodic service and recalibration.</p> <p>My approach to the Luna Pro has been to clean/repair and then re-calibrate the meter to Silver Oxide cells (1.55 V). Silver oxide cells, like mercury cells, have a very stable voltage throughout their life. (Alkaline coin cells, often confused for silver oxide cells, do NOT have a stable voltage.) I don't know whether you can recalibrate to the 1.55V silver oxide voltage with the Pentax spot meter.</p> Link to comment Share on other sites More sharing options...
William Kahn Posted May 30, 2015 Share Posted May 30, 2015 <p>The WeinCell battery should work, if the original battery was the PX625/PX13 mercury cell battery. I've used it for years to power the light meter in my Olympus OM-1.</p> <p>(Edit: Sarah beat me to it...)</p> Link to comment Share on other sites More sharing options...
lex_jenkins Posted May 30, 2015 Share Posted May 30, 2015 Wein batteries are overpriced. #675 zinc air hearing aid batteries work just as well for a fraction of the price, even with the higher prices than 10 years ago. Be sure to replace them often. They'll last anywhere from one to six months. Exhausted batteries will leak through the air vents. Usually spring pressure is enough to hold the smaller batteries in place. If not, just make a shim from any non-conductive material, like a rubber or plastic gasket. Link to comment Share on other sites More sharing options...
finnegan Posted May 30, 2015 Author Share Posted May 30, 2015 <p>I had decided to skip the whole thing and ask for my money back and my return of the meter. Actually the Seller hasn't accepted the payment yet/, So, I thought I'd ask that he cancel the payment or just let it expire which it will in about 5 days and meanwhile I send the meter back.</p> <p>But I did buy it after all so, I'll a get a Weincell but start with the hearing aid battery and try that. <br> I'll post a report after.<br> Thanks So much!</p> Link to comment Share on other sites More sharing options...
bebu_lamar Posted May 31, 2015 Share Posted May 31, 2015 <p>Yes if you buy a meter to use then avoid one that uses mercury battery. It's not worth it. Besides a meter that requires a constant battery voltage to function is of poor design any way.</p> Link to comment Share on other sites More sharing options...
finnegan Posted May 31, 2015 Author Share Posted May 31, 2015 <p>I tried the 675, think it is, hearing aid battery. It's too thick the to allow the cover, the kind you screw in or out with a coin, to close. So I ordered the WeinCell. Hopefully that will do the trick.</p> Link to comment Share on other sites More sharing options...
bebu_lamar Posted May 31, 2015 Share Posted May 31, 2015 <p>If you get the LR52 battery it would fit and work but the accuracy is affected. </p> Link to comment Share on other sites More sharing options...
GerrySiegel Posted May 31, 2015 Share Posted May 31, 2015 A lot of cameras used a mercury battery and my understanding that the voltage was fairly stable during the life of the battery and then a large drop. So it became necessary to find a substitute with the same voltage curve for devices and cameras that did not have an internal voltage regulator. If you find a mercury battery that the EPA has not restricted, it will last just short of forever. I am now using a Wein combo for the Analog resistance style Luna Pro and find it gives a close readout to several cameras with short tele lenses and also with my Minolta IV which has voltage regulation built in. There are times when a handheld meter is just the ticket. Like everything, they may need adjustment and service. Last time I looked Gossen still offered service for the oldies. I would consider a Sekonic if I had to replace my Minolta. Brighter display readout. The one handed Gossen is still a worthwhile item and is most affordable used. Link to comment Share on other sites More sharing options...
GerrySiegel Posted May 31, 2015 Share Posted May 31, 2015 I show several that I have owned over the years, Bill. Each had its pluses and minuses. The selenium Weston meter was simple and required no battery. Mainly good for reflected light. I found it in my ancient box and somehow it got salted and is now laid to rest. The Minolta is fairly complicated but is a solid piece of gear, even if you find one used. Some company has taken over Minolta meters, cannot come up with name off hand. They are a good value. Readout is fainter than I like. One AA alkaline, easy to find. The Gossen someone gave me. Mint conditon and very easy to use. I had two mercury cells which lasted years...Wein works OK so I expect Lex's suggestion will also...all Wein seems to add is a little bushing plastic... With the Gossen semi spot adapter I got for 20 bucks it makes a decent reflective semi spot which I like and keep on it...easy attachment is nice. The attachment for the Minolta also does the job but is kind of bulky and takes more care to fit on. If you buy a super duper new or late model Sekonic it will last a couple lifetimes I betcha and save in film cost and earn its keep. But a used one is fine...for a budget handheld to gain and to gain experience with metering light. Even the old Weston took some thinking and getting used to, and it came with a smart booklet.<div></div> Link to comment Share on other sites More sharing options...
finnegan Posted June 4, 2015 Author Share Posted June 4, 2015 <p>Well, the WeinCell was too thick, like the hearing-aid battery so I asked Seller for return and my money back. I just contacted him, no time for a response yet. And next time I'll find out FIRST of meter uses mercury batteries.</p> Link to comment Share on other sites More sharing options...
rogerwb Posted June 4, 2015 Share Posted June 4, 2015 <p>Buy the Wein cell once. W<br> hen the battery expires, push it out of the adapter ring and replace with a 675 hearing aid battery.</p> Link to comment Share on other sites More sharing options...
finnegan Posted June 5, 2015 Author Share Posted June 5, 2015 <p>I'm sorry Roger, don't understand what you mean?</p> Link to comment Share on other sites More sharing options...
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