Projecting 8x10 (or other LF) transparencies?greenspun.com : LUSENET : Large format photography : One Thread
I am shooting 8x10 color transparencies and am thinking whether it's possible to project them. I guess the only option would be to use an 'overhead' projector - the kind used for business presentations in the corporate world. Has anyone tried this? I wonder what the quality would be like. Such projectors with decent light output cost several hundred dollars, so buying one for experimentation would be risky.
-- Dan Benjamin (firstname.lastname@example.org), December 25, 2001
Couldn't you project ANY format via an enlarger set up horizontally?
-- John Burnley (email@example.com), December 25, 2001.
I would think an experiment would be quite inexpensive - most cities have presentation rental businesses who have OHP's for rent at reasonable rates. I doubt you'd be pleased with the quality, and would definatly recomend boxing in the OHP, so the light from it doesn't lower the apparent contrast of the projection, but without trying it, you can't know if it'll be good enough.
-- Eric Boutilier-Brown (firstname.lastname@example.org), December 25, 2001.
Overhead projectors usually have a fresnel lens to distribute the light evenly under the glass where you put the transparency, so they typically project the pattern of the fresnel. The lenses aren't terribly sophisticated either, so they usually have some pincushion distortion. It doesn't seem like a promising approach.
-- David Goldfarb (email@example.com), December 25, 2001.
Overhead projectors designed to project photographic transparencies have a stage between the lens and the base so the film is not placed on the fesnel of the projector. 20 odd years ago Linhof made an adapter that fit a Liesegang overhead to project 617 Technorama images. It worked well but did not sell which resulted in its' being discontinued. It should not be all that difficult to rig up a similar system.
-- Bob Salomon (firstname.lastname@example.org), December 25, 2001.
Thank you to all the responders. It seems the best way to go optically might be an enlarger, but for 8x10, even used I imagine they are either too expensive or too hard to find. Renting an overhead projector is something I hadn't thought of and it should enable me to see if the pinchusion or other distortion is objectionable. Also I hadn't thought of building a stage to separate the transparency from the fresnel. Of course, just viewing the 8x10 transparency on a light box really is wonderful and can't be replaced by anything, but I just may rent an overhead to what what results of projection are.
-- Dan Benjamin (email@example.com), December 25, 2001.
Are you going to be showing your transparencies on location? If not, you might try finding an old Elwood 8x10 enlarger. The model I have pivots so you can project horizontally. They usually sell for a couple of hundred dollars or less. It might be fun to rig a filter holder on one so you can make big-big cibachromes. Photographic systems has Ilex 229mm barrel lens on sale ---I think they're around $40-70. Mine works fine as an enlarging lens , I wonder how it would do for projecting trannys? This set up might make an intersting option for you. Way to ponderous to cart around for presentations, though!
-- John Kasaian (firstname.lastname@example.org), December 25, 2001.
What about the heat that overheads throw out? Would that cause a problem? Dean
-- Dean Lastoria (email@example.com), December 27, 2001.