Looking for the "Lightroom" folder. Need to build a 4x5 slide projector

[maddoc]

If it would give a strong enough picture, I would go for that. I think projecting a 4x5 slide film vs. a transparency with writing on it may be a little different though.

The ones we used back then at university were strong enough for color-copies of photos from magazines or books. RVP might be a bit dense but I would try it ...

 

[Rob-F]

I don't think heat would be such a big problem. A 4 x 5 has 20 square inches. A 35mm slide has 1.5 square inches. So the heat will be distributed over 13 times more area than for a 35mm slide. A typical slide projector uses a 300 watt halogen lamp. Assuming you don't need to cover a larger screen than say, 4 by 6 feet, 300 watts should do the job and the slides should run pretty cool. With the right screen, you can even go larger.

I wonder if some of those flat plastic fresnel-type magnifiers sold in places like Walgreen's, etc., could serve as the condenser? Maybe if stacked up. Otherwise, the lenses from a condenser enlarger should be good. You could put a 300 watt projector bulb behind it. ELH for normal brightness; ENG for extra bright. Don't forget the fan. I'd use a muffin fan. These are common in electronic equipment, and you can get them in electronic supply houses and online from places like Mouser.

 

[sevo]

If it would give a strong enough picture, I would go for that. I think projecting a 4x5 slide film vs. a transparency with writing on it may be a little different though.

As I said, some high quality overhead projectors could be fit with smaller illumination systems and the matching lens to enable projection of large format film, translucent scientific samples and the like.