"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Mary Fisher wrote:


We turn them off when we're not using them - of course. Shouldn't ALL
electrical equipment be turned off when not being used? It makes all
kinds of sense - even for little old me.


Except that when you *do* want them, you won't be able to see them to turn
them on 'cos it will be dark!

It's very rarely so dark that you can see nothing at all.

It takes a lot of skill to light proof a photographic dark room thoroughly.