Selenium cells aging in light?

I know this has been in many forums, but has anyone got any real knowledge?
Should I store selenium cells covered or not? As I have my cameras in vitrine there is no direct nor hard sunlight to the cells, but some light does come to them. Is it harmful for the cell, or ist it a myth?

I've always heard they should be covered and kept in the dark.

Steve

i allway stick on the cell window a piece of black plastic tape (like that use by electricians)
you must protect selenium lightmeter from continuous light ....(remember the kiev's lightmeters folding flaps...)
i did that on all mщy zenit bodies (E and EM..)

quote:

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Originally posted by cedricfan

I know this has been in many forums, but has anyone got any real knowledge?
Should I store selenium cells covered or not? As I have my cameras in vitrine there is no direct nor hard sunlight to the cells, but some light does come to them. Is it harmful for the cell, or ist it a myth?

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Excessive light and humidity will degrade the efficiency and shorten the life of a selenium cell.
A certain amount of light generating a miniscule amount of current in a selenium cell causes the needle to move accordingly. It has to be a rather delicate litle instrument and should be treated as such .
Since we already know that selenium cells lose their efficiency over a period of time anyway it makes good sense to keep it covered and in the dark (case or pouch)) when not in use and stored in a dry place. This shouldn`t be a problem since they come in a case of some sort.

The meter in my Kiev 4 is only about 1/2 stop off but is so strong that if I open it directly to the bright sun it will shoot off the scale and stick there. I have to tap it lightly to get it back to the rest position.
John

oh no! You're telling me that me displaying the cameras without cases on the shelf actually damages them? Jeez! I need to start doing what Alain is doing... but... doesn't the electric tape leave some glue after some time, especially in the summer? Can anyone suggest an alternative? Some plastic tabs and scotch tape? But that is even worse...

Thanks!
Vlad.

http://f1.grp.yahoofs.com/v1/4PHlR7GbZRQI9vIn881OeQoQoEAWvmIEgbBBx4exMO70JEEbbbH0lNbNsyuEUeOTazl8SDxuLmEu5jD6HmzH/Misc/E_EMcell.jpg

Smena rules

How to store selenium celled Zenits with working cell? Simply print this, glue on black self adhesive tape and put it on cell when camera is in display vitrine...

That is what I once wrote in ZCG but stopped doing as I was not 100% sure it is needed. I may have several more "cell pictures" still somewhere, must dig into my archives...

And yes, electric tape does not leave residue if you replace it every 10. year and don't store cameras in sauna or greenhouse!

Smena rules

Prints in real size at least in my printer

Smena rules

Of course my comments above were made assuming the metering lens had a Kiev like cover that keeps out most of the light but I see this is not the case for many other cameras. I also did not consider displays where the leather case would not be used.

Having been a certified electrician for the past 48 yrs I am very familiar with selenium cells and other types of photo cells. I have always used black vinyl tape (3M brand) to block the light and deenergize these cells.(usually testing purposes) Some of which required 2-3 layers to block out direct sunlight but of course that should not be necessary for the intended purposes on this thread. One thickness of a good tape should be sufficient for such low powered meters.
I would caution against using cheaper discount store black vinyl tape for long term storage or display in any unusually warm environment as the adhesives used are probably not spec grade and can often leave residues that could be difficult to remove especially on black paint oor leather (ette).
3M (scotch) is a high grade electrical tape undoubtedly the most popular brand black tape used in the trade and for good reasons. 3M or other high quality black tape can be found in any good electrical supply store.
But in the end none of the above should cause much harm to a (metal) camera surface and how hard would it be to use a small amount of lighter fluid or solvent to remove tape residue. I`d only be overly concerned if the tape was adhered to a soft or painted surface.

Now the above is all well and good for newer harder plastic or glass cell windows but we really have to consider the reality that some of these cell windows are of a softer plastic and the possibility of having to clean tape residue from them can be damaging. If it were me I`d not hesitate to place dark paper or cloth between the cell window and tape to prevent the possibility of having to clean tape residue from it at a later date.
John

Ha! These are great! Thank you Juhani! I will try to print these! [:) ]

John thank you! I do like to take hot baths with my Zenits so I have think about that electrical tape....


Vlad

The Selenium cells life can be very long, 20 or more years. I doubt that room lighting would hurt them. Bright daylight would have a bearing on the longevity, They were used for many years because cameras had room to spare then ,also that was the technowlegy then. The cds and relatives require a voltage to operate and just regulate the flow and don't produce the voltage to run the meter. The modern cds and gallium types are more sensative in lower light levels. So it breaks down to how do you shoot pictures, In low light or daylight. And as far as aging goes in the selenium cell most metering systems have a potentiometer to adjust and compensate for some aging. Don