I've had my 3100MP for about two years now and I only just recently noticed this. Don't know if it's a new problem or not. In fact I'm not sure it's a problem... but it sure looks as though it must be. 

There appears to be, within the lens, a curved, matte black surfaced thin object, or perhaps a coating on one of the lens surfaces, that is blocking almost the lower half of the lens!

It seems to be at a slight angle, making me doubt that it's supposed to be there. 

It does not cast a shadow on the projected image (any more than the diaphragm in a camera lens produces a "porthole" effect on the film) but it must certainly be cutting down on the light output.

Can anyone with a 3100MP take a good look at your lens and see if you're seeing the same thing in yours?

Does anyone have any idea if this stuff is supposed to be there? If so, what function does it serve? aside of course from blocking some of the light. If I took this to a lens repair place and had them open the lens and remove the coating, what would be the result?  Aside from more light.  Would it let out some glare that is maybe being blocked now?

I've looked at a LOT of small DLP projectors lately and I've never seen anything like this in their lenses. 

The opaque area does not move or rotate in any way as the lens is focused or zoomed.

This sort of thing is hard to catch in a photo, but here are attempts.

In this one the light is coming up at the projector from the bottom, and we're looking down at the projector from the top:

In this one we're looking up at the projector from underneath it.  Light is coming from above the projector's top surface.

Anyone?

Message Edited by jeh14 on 09-28-2004 11:58 PM