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[MF3D.FORUM:1118] Re: Projection Lenses


  • From: Paul Talbot <ptww@xxxxxxxxx>
  • Subject: [MF3D.FORUM:1118] Re: Projection Lenses
  • Date: Sat, 19 Aug 2000 00:14:54 -0500

Do any of the (few) folks with MF projection experience
have some thoughts to share on these questions of Tom's?
I'm interested to learn more!

Tom Hubin wrote:
> 
> 35mm projectors typically offer 3 focal lengths for projection from the
> front, middle, and back rows of the audience.

I think most stereo projectors come with one FL lens.  The
venerable TDC had a choice between 4" and 5" FL, but I think
it was generally sold "either/or." 

> Is this also true for MF projection?
> 
> What focal lengths and fNumbers are used for various projectors?
> 
> What does a new or used, mono or stereo, MF projector cost?

A lot.  MF stereo projectors have not been commercially manufactured,
that I am aware of.

> Is an MF projector generally larger and/or heavier than a similar 35mm
> projector?
> 
> I have been doing some number crunching for condenser optics for various
> theoretical slide formats and projection lenses. My math indicates that
> for a well designed illumination system (light source plus condenser
> optics) that the lower the fNumber of the projection lens and the larger
> the slide format, the more light delivered to the screen. Any comments?
> 
> I do not mean to suggest that you can increase the diameter of your
> projection lens to get a brighter screen image. But rather that the
> illumination source and optics are designed to fully fill the projection
> lens that is intended for use with the projector.
> 
> So is it generally true or untrue that MF screen images are brighter
> than 35mm screen images?
> 
> Is this too technical for this list? Should I move the questions to
> Tech3D? 

This list tends to be more technical than Photo-3D, so I think it
is fine for here.  I just wish more of us had the experience and
knowledge to answer your questions!

Paul Talbot