Lightmeters - some questions

[Telecolor 3007]

Hello. I do have some questions about old light meters. I have two Selenium photo cell "Gossen". Both showing different values. I don't know which one is wrong, because I don't have other meter. I guess that photo cells got some reading modifications because of the time. Is there any way to adsjust this.
Other thing is that in the past there where some 1.35 Volts batteries that can't be produced today because of enveriomental reasons. Can such ligthmeters be adjusted if you put 1.5-1.6 Volts batteries. Adjust to make correct readings. I have a camera that haves such lightmeter.
Some of the old (pre mid-'70's) are using batteries that are still produced, but they are rare.

 

[DesertRatt]

I'd try calibrating an old selenium meter to a modern working meter. Find out what the error is...1 EV? 5? Etc.

There us a battery called the Wein Cell which is sold today and is 1.35v. About $5. I've used it in old Yashica cameras.

 

[ic-racer]

Zinc cells are close to 1.35. I use them in all my equipment that was designed for mercury batteries.

 

[Telecolor 3007]

I put Zinc one in my camera and it leaked...

 

[ConradH]

Selenium cells age, some say more so with exposure to light. You can get a rough idea of accuracy using the sunny-16 rule. Go outside on a sunny day and see if you get readings close to 1/ISO for the shutter speed at f/16. I still have a few selenium meters that are fairly accurate.

Mercury cells were wonderful, 1.35 volts, very accurate and stable over their entire working life. Light meter circuits were minimal and took maximum advantage of that stable voltage. Yes, you can use a zinc-air cell but they die quickly once unsealed. You can add a diode to drop the voltage of a 1.5 volt cell, but fussy about the particular diode and the cell voltage still drops with use. I just don't bother with 1.35 volt stuff anymore as it's a pita and there are other far better options. I often recommend the Gossen Luna-lux SBC because it uses a standard 9V battery and, using a null technique, is extremely accurate. Fairly common on the used market for about $50. There are much more sophisticated meters that use common batteries, but usually for more than I want to spend. They can often do flash as well.

Just because they're cool and have a long & interesting pedigree, going back to the Norwood Director Norwood Director - Camera-wiki.org - The free camera encyclopedia, I recently got a Sekonic L398A. It requires no battery, is a bit quirky and weighs a ton, but very accurate Available both new and used. https://www.bhphotovideo.com/c/product/435535-REG/Sekonic_401_399_L_398A_Studio_Deluxe_III.html