Hello,
I have a 1963 camera that uses a 5mm diameter cds cell to collect light to determine aperture and shutter speed.
However the cell seems to be massively oversensitive. Even when I place a finger over the cell the camera meter registers some light. It should drop down to show no light.
There is no way on the galvanometer to adjust it so I am wondering what has broken.
The camera runs off a 1.35v volt button battery.
Is there anyway to test the cds cell to see if it has got shorted out internally, would this cause over sensitivity?
Wires and battery seem in good condition, but could internally corroded wires cause this?

Any help gratefully received!!

Thanks
David

 

Hello,
I have a 1963 camera that uses a 5mm diameter cds cell to collect light to determine aperture and shutter speed.
However the cell seems to be massively oversensitive. Even when I place a finger over the cell the camera meter registers some light. It should drop down to show no light.
There is no way on the galvanometer to adjust it so I am wondering what has broken.
The camera runs off a 1.35v volt button battery.
Is there anyway to test the cds cell to see if it has got shorted out internally, would this cause over sensitivity?
Wires and battery seem in good condition, but could internally corroded wires cause this?

Any help gratefully received!!

Thanks
David

You haven't really convinced me that anything is wrong. You should take a known-good camera side-by-side, and use it to see if the test camera produces exposure advice that doesn't match up. Check and double-check the battery, too. I think a failing battery can cause some pretty goofy behavior.

Also, can you see the meter change value if you set a different ISO? Not sure meters back then allowed for that?

 

yes done that. I suspect the CDs cell is OK as it registers light.
Battery is brand new, but 1.55v rather than 1.35v which wouldI think, cause a higher reading.
However testing with a known good camera gave a reading of f2.8 at 1/125 sec with 400ISO, my problem camera gives a reading of f8 at 1/650 sec with 25ISO!
All contacts and wire give a good resistance reading with a multimeter, so no dodgy contacts that I know of.
I can only surmise that the galvanometer is "blown" (it has no adjustment screw), or the CDs cell is internally shorting out giving very high readings.
It's very puzzling, never come across this before!

Thanks
David

 

Battery is brand new, but 1.55v rather than 1.35v which wouldI think, cause a higher reading.

Isn't a higher reading what you are seeing?

The circuit is very sensitive to the battery voltage and yours appears too high
Is it the exact replacement?
Different type batteries of the same physical size can have different voltages.
It sounds like you may have an alkaline or silver-oxide type, rather than a mercury type required, which gives the desired and stable 1.35V.

 

The battery in a 1963 camera is probably a mercury cell. They exist on eBay and probably other places.