Originally Posted by RandyFreeman
I finally got a chance to try my prisms. I set the prisms on a table in front of my projector. The Crystal Factory prisms have a greater angle than the prisms from Massillon Plaque. Because of this I needed to set the new prisms at less of an angle to the light path. This will make my new housing 1" shorter and 1/2" wider than my old housing. I have a projector that has a recessed lens and the geometry of the new prisms make it easier to get the prisms slightly closer to the lens. Every little bit helps in this situation.
I did this experiment during the day, in a room with lots of light. I was just trying to figure out the angle of the prisms so I can build the housing. I did notice that the coated prisms seem to have reduced the reflections. In fact I didn't see any reflections on the walls. With my uncoated Massillon Plaque prisms, under the same condition, I saw some strong reflections on the walls.
My old housing was fully adjustable. This time I'm going to make a simple housing that isn't adjustable. I'm just going to set the prisms at the angles that I determined during my experiment and I expect the new lens will work perfectly.
very valuable piece of info. Thanks
I am glad I returned the massillon plaque prisms. They
were pretty much like mirrors!
and yes I had to tilt those prisms a lot to get the stretch as
the angles were small. This made the beam on the second
prism way too big, falling very close to the top edge, which could
cause more reflections.