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CJ
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 23, 2005 - 02:38 am: | 
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Has anybody heard of this manufacturer? When Googled, almost all of the links returned are in German. I appears to be a decent meter, albeit constructed entirely of plastic.
I'm thinking I'm going to need this, as the meter in my Ricoh 500G suddenly reads only f/22 with battery, and rests in the gutter at f/2.8 without one; nothing in-between. |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 23, 2005 - 03:58 am: |
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The manufacturer of this meter was made by 'Feingeraetewerk Weimar' which translates into 'Manufacturing plant for precision devices of Weimar' - probably a manufacturer for industrial instrumentation. The Weimarlux was probably the result of an east german law forcing all manufacturers of industrial goods to put up a line of consumer goods to improve the market situation.
However, they currently can be bought dirt-cheap on german ebay (I found a fully functional one on a fleamarket for USD 5). They feel a bit flimsy but seem to be quite accurate. There is a german website where someone tested it against a Gossen Lunasix and found almost identical results. It runs on a PX625 mercury cell. It has a read out scale running from 1 to 20 or so, but this is NOT calibrated in EV steps so you can't compare readings directly to other light meters - you always have to check the f-stop/speed combo.
BTW there was a complete line of Weimarlux meters but only those with a CdS designator have a CdS cell - all others have selenium cells with all known disadvantages. |
CJ
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 23, 2005 - 04:15 pm: |
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Thank you again, Winfried! Yes, I can understand they go for very little money--I think I paid $7US for mine.
Incidentally, does anybody know the correct way to compensate for the presence of a higher voltage battery in units like these? Being in the US, the only 625s we have access to in stores are 1.55v, not the mercury 1.35v batteries.
I've read on Matt Denton's excellent site that to compensate for a situation like this, one needs to set the ASA to 2/3 of your actual film speed. Correct?
Also--I'd love to use the solution that Rick Oleson details on his site for modding a smaller but correct voltage battery to replace the mercury 625s, (I've done it for my other cameras) but the Weimarlux meter has this strange battery contact setup, where there's a metal ring that the battery fits into--which acts as a contact--thus eliminating the rubber O-ring setup as useful...
Has anyone tried aluminum foil as a workaround for situations like this? |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 24, 2005 - 04:12 am: |
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I have posted this many times in many places: the higher voltage of an alkaline cell CANNOT be compensated. Even if you get correct readings initially, the voltage of alkaline cells is in no way constant over time and you would have to recalibrate the meter again and again.
However, the Weimarlux CdS is a fairly simply designed meter and I happened to find the diagram in an old east german photo book. There are three variable resistors inside: one sets the readings at the higher end, another at the lower end of the range, and the third sets the battery indicator. If you manage to put a silver oxide battery into the compartment (silver oxide batteries have stable voltage of 1.55V) it should be possible to recalibrate the meter to this battery voltage. But again, this is NOT possible with alkaline cells. Another practical solution is to use silver oxide cells and solder a Schottky diode in series with the battery. |
CJ
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 24, 2005 - 10:35 pm: |
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Thank you Winfried. I don't think I made it clear that I've been fitting silver-oxide batteries to my cameras that require 625s. I'm definitely not using alkalines. I've read numerous posts on this site, as well as that Topcon (?) site that discusses the discharge curves of various batteries.
Also--thank you much for the Weimarlux resistor info. |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 25, 2005 - 04:07 am: |
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I see - I have not seen any silver-oxide batteries in 625 format over here in Germany, so I had no clue they are available in 625, too. However, for b/w and color print film it might be sufficient to compensate by setting the ASA dial, these films do not need to be exposed more precisely than within +/- 1/2 f-stop.
I have heard that some zinc-air/Wein cells come with a metal adaptor allowing to use them in 625 compartments. Also, the (expensive) Wein cells should be available in genuine 625 size, too. |
WernerJB
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 25, 2005 - 03:53 am: |
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Winfried, as always, is right, this lightmeter IS somewhat flimsy, even inside: soldering joints are obviously as bad as the ones in early Sixties' Japanese cameras. Mine has got a battery compartment for 675s (one of the later models, I guess), so replacement is easy. When I got it worked only intermittently and during troubleshooting I discovered several points inside that needed resoldering. Like on the top cover of Minolta SRT models the central screw is hidden under the red dot on the dial, the meter can only be opened from the front. After lifting off of the round dial as a whole and removal of the blach sqare dial (in direction of the cell, be careful not to bend the needle!) the innards become visible, further dismantling is not advised and requires the taking apart of the more delicate parts ! |
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