Should the lens cap stay on when projector is not in use?

If it's ceiling mounted and not subject to fingerprints (usually from passing toddlers) I wouldn't worry about it. Yes, a slight amount of dust may accumulate, but a good microfiber lens cleaning cloth will take care of that.


Of course, you'll probably get some responses from those who put it on everytime, but I don't see the benefit.

I'm probably at the far end of the spectrum. I don't cap mine at all and in over a year all I have ever done is blow at it to get the large surface dust off. The little stuff that remains looks exaggerated when it's lit up but it doesn't (to my eyes) effect image quality.