For the first time in a couple of months I've used my iSight camera which is built into my Intel iMac and found that it is requiring an enormous amount of light but still producing an extremely dark picture. In fact it is totally unusable.
When I go to try it out with iChat Video Preview it will produce a faint glimmer of an image for about half a second then go black. The sound is working fine. It behaves exactly the same with Skype as with iChat.
When I last used these programs, a couple of months ago, everything was fine and I could get a good picture even with very low levels of light.
I have upgraded the OS since that time. I don't know if that will have had an impact. I could have been on 10.5.2 when I last used the camera, I can't remember, but I'm now using 10.5.4.