Selenium Cell in Zeiss Super Ikonta IV
I'm still digging through the camera collection I inherited. Just coming to the bottom of the pile. Yesterday, I found a Zeiss Super Ikonta IV.
It's got a selenium cell light meter. It looks like the meter has gotten weak with age.
Comparing it to my Gossen meter (CdS cell) which I trust, the meter in the camera seems to read about 6 EV too low.
I would like to run a roll or two of film through this camera to decide whether I want to keep it as a shooter.
Question: Should I assume the meter in the camera is shot?
Option #1: When using selenium "stack" rectifiers in old movie theaters it is sometimes possible to rejuvenate them if they aren't too far gone. I don't suppose that's possible in this case. Is it?
Option #2: Is it possible to assume that the 6-EV offset is constant and just add 6 to whatever the meter says?
Option #3: Probably the most likely solution would be to just keep the Gossen in-hand and use that instead of the camera's meter. It's an uncoupled meter anyway. It's not that much of an inconvenience to use the hand held one, I guess.
At this point, I'm thinking Option #3 is the answer but, just for knowledge, what do you think about options #1 and #2?
The one I got as a gift I used recently. I don't know if it's the same problem or it's just how selenium cells work, but it's pretty much spot on in bright daylight. It's not accurate indoors. I just carry a small meter when I shoot with it. It's a lovely camera.
In my limited experience, when selenium cells begin to fail, their error is non-linear. A reliable hand-held meter is a better option.
I would say that it actually is linear i.e. the voltage output will double for each doubling of light but as we measure light on a logarithmic scale, it is unlikely to be six stops out over the whole range of lighting possibilities.
Originally Posted by Jim Jones
"People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.
If you like using the camera, you might want to find out if Quality Light Metrics would service the meter.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
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I just took the camera out and tried a roll of film in it. Everything seems to work, mechanically speaking.
I used my Gossen light meter instead of the built-in. It's not that much of an inconvenience, really. Even when working the camera's meter is not coupled so you still have to transfer your reading to the lens controls. Just having the hand held meter on a lanyard around your neck isn't that much more of a burden. Besides, I've taken to carrying my hand held meter with me even when I use a camera with TTL metering. Regardless of whether you trust the TTL meter or not, it's still a good habit to carry a "backup" meter anyway. Isn't it?
Anyhow, I don't think the camera's meter is failing in a linear manner.
I compared its readings to the Gossen and I found that it is anywhere from 4 to 8 EV off. I can't tell if it is predicable. It was pretty cold outside today so temperature might have affected things. The camera's meter always seemed to read low. One time it would read 4 or 5 stops low. Another time it was nearly 8 stops low. It could have been the cold but, no matter which way you slice it, the meter isn't trustworthy. Don't you think?
Just so you know: Even though it was cold out I protected the camera as much as possible. I wore a heavy, winter parka and I kept the camera folded up and stored it in an inside coat pocket when I wasn't using it.
Besides that, I liked using the camera. I'll develop the film soon and see how it turns out. If the pictures come out as I expected, I just might keep this camera as a shooter even with the dead selenium cell.
My old ~1963 Kodak Instamatic 500's Gossen Selenium meter seems bang on outdoors in comparing to my not quite as old 1973 Canon FTbN's Cds (Mercury cell powered) meter. Indoors the Selenium cell doesn't do much but with a manual flash you don't need it anyways, just dial in the ISO on the flash, set the indicated aperture and shoot away.
You might find this link interesting. http://elekm.net/zeiss-ikon/repair/meter-repair/
Mr. Elek is a regular here. I find his website really interesting and useful.
The Gossen meters on the Retina cameras appear to be sealed units, which protects the selenium cell from the elements. It's uncommon for a Retina meter to be dead.
The Zeiss Ikon camera meters aren't, and for the most part have just the metal flap and the slotted plastic cover over the selenium cell. I don't have a Super Ikonta in hand, but for some Zeiss Ikon meters, the cell isn't dead. Rather, the contacts have become oxidized. The way that you can sometimes tell is by the reaction of the meter needle. A sluggish needle usually indicates a cell that is near the end of its life -- usually.
From what you describe, that seems to be the case with your camera. When you point the meter at a bright light source, the needle should instantly jump.
If you're a bit of a tinkerer, you probably could get the cell from a Zeiss Ikon Ikophot light meter and swap it for the one in the Super Ikonta. Obviously, you'll want one with a live cell.
The Super Ikonta, if it has the Tessar, is an excellent camera, and I would simply use a handheld meter. It's like having a Super Ikonta III.