The SSubstitute for a Selenium Lightmeter!

[ianbelinchon]

Hi everybody. Happy new year!!
Anyway, I've got a 8mm movie film camera and it has a selenium lightmeter but, unfortunately, it's dead. I've read about cleaning the contacts can make it revive, but I've also been thinking about using Silicon photocells (like the ones calculators have for solar power). To my understanding, they work on the same principle: Light excites the material's electrons and it emits the current that the needle needs.
I'd like to know if anywone has tried this out, or if someone could measure the voltage and/or current flow from a living selenium lightmeter for a fixed reading of light. (ie. 100ASA, 1/100, f/11)
Thnks. Any comments and sugestions are welcome.!!! 🙂

 

[Chriscrawfordphoto]

It could work. The latest versions of the Sekonic Studio Deluxe meter actually use a silicon rather than a selenium cell. When I was in high school, I built a working incident light meter with one of those silicon photocells, purchased at Radio Shack, and a microammeter.

 

[Joao]

Hi
Maybe you find something useful here
http://www.tomtiger.com/
scroll the left side, click on th "Zenit Repair Project" and loook there for "Repairing the Lightmeter". Good pictures , detailed instructions and technical data. I hope it helps
Joao

 

[FallisPhoto]

Hi everybody. Happy new year!!
Anyway, I've got a 8mm movie film camera and it has a selenium lightmeter but, unfortunately, it's dead. I've read about cleaning the contacts can make it revive, but I've also been thinking about using Silicon photocells (like the ones calculators have for solar power). To my understanding, they work on the same principle: Light excites the material's electrons and it emits the current that the needle needs.
I'd like to know if anywone has tried this out, or if someone could measure the voltage and/or current flow from a living selenium lightmeter for a fixed reading of light. (ie. 100ASA, 1/100, f/11)
Thnks. Any comments and sugestions are welcome.!!! 🙂

Modern silicon photovoltaic cells are available from Edmund Scientific. They sell "grab bags" of up to 70 cells (and pieces of same) for about $10.

I have tried the "reviving trick" and it didn't work for me; apparently it does for some people though. Replacement with a modern solar cell does work, but you have to make allowances for different voltages.

What you do is get a potentiometer (variable resistor) and wire that (temporarily) in series with the solar cell and the camera. You adjust the potentiometer until you are getting good exposure readings. Then you disconnect the potentiometer and measure its resistance. After that it is simply a matter of soldering a resistor or two (with appropriate ohm values) in series with the battery and meter.

 

[ath]

The spectral sensitivity of silicon cells is heavily biased toward red and infrared. That's why the first silicon cells in meters were referred to as SBCs (Silicon blue Cell): they simply had a blue filter in front of them (and still have today).

 

[ianbelinchon]

great info! thanks a lot. I'll see what i can do and will keep you informed!

 

[thawkins]

Very Interesting - Could this repair be applied to dead Leica meters?

 

[ianbelinchon]

Very Interesting - Could this repair be applied to dead Leica meters?

I'm sure it could! Lightmeters are lightmeters after all. 🙄

 

[FallisPhoto]

Very Interesting - Could this repair be applied to dead Leica meters?

If it will work for a dead Zenit, or for an Olympus, I'm sure it will work for a dead Leica too. The technology is pretty much the same, at least for the light meter's power supply. http://www.xs4all.nl/~tomtiger/zenrep/meter.html http://www.thermojetstove.com/Autoeye/meter.htm

 

[john341]

Try Dick Smith , Tandy for a photoelectric cell or solar cell..it worked for me on a 35mm movie projector and produced great sound..should do similar for an exposure meter??

 

[kingsley244]

Folks, any updates on your experiments ?

 

[Blanc]

Tried real tests... Not the same wavelength response than a film.
Filtering (bertween blue and green) is needed and thought to achieve, plus once filtered you'll need an extra battery to compensate your filter 's effect in low light, sodium light...
Giving precise instructions is not easy as each element got it's own response curve that can be really different from one brand to an other...