In article , ethz95@dds.nl says...

>Recently, I bought an old Gossen Lunasix 3. This light meter works
>with a CdS cell. Someone told me that CdS cells get less sensitive
>when their're getting older and after about 25 years they quit working.
>I know that selenium cells have a limited lifetime. But CdS cells??
>Can someone please inform me about this?

I kinda doubt all of the above - I have some Weston selenium meters
from the late 1930's that work fine, and old Nikon F meters with CdS
cells can also work fine (usually, problems that appear in old meters
are contact problems, not cell problems, and even old faulty selenium
cells can be disassembled and the internal contact areas cleaned,
which often restores their operation to normal [if pressing on the cell
makes it work, cleaning probably will, too]).
Hope This Helps