Re: [Leica] Pradovit P150--and RT300

["Jeff S" <segawa@netone.com>]

- -----Original Message-----
From: Gary Todoroff <datamaster@humboldt1.com>
>The RT300 projects beautifully, but I have a question for the LUG. The
>light path of the RT300 has the bulb facing at a right angle to the
>condenser/film/lens light path. A special "dichroic" mirror sits at 45
>degrees to reflect the bulb down that path. My mirror has a mottled
>appearance with a green cast to it, which is probably reducing light output
>and maybe even affecting the color. Does anyone know who carries the mirror
>as a part? Can it be resurfaced? (Leica no longer carries RT300 parts).
>
Very interesting, Gary; I wonder if it's using a "cold mirror" to reduce
damaging heat, rather than a very thick heat absorbing element, as the
American Kodak projectors do. If it is such a mirror, it may be difficult to
resilver, but Edmund Scientific (www.edsci.com - ask for the big optics
catalog, not the skinny one of consumer goods) sells new ones. A cold mirror
would pass the infrared portion of the light straight on through the glass
as if it were clear, but reflect the visible portion at a right angle. If
it's an ordinary front-surface mirror with some sort of (protective?)
coating, a number of places catering to telescope makers could resilver it.
I wouldn't mind seeing the innards of that thing--if it is indeed a cold
mirror, whatever's behind it gets flooded with IR, and should get mighty
hot--wonder how they accomodate it.

When you get a chance to try it out, why not post a review? Besides outright
performance, it's good to know whether it's likely to be the first projector
you reach for when it's time to give a show, or whether something else
captures your fancy by virtue of convenience, etc.

Jeff