are there any lens that can make the image of a large screen to smaller size so I can use with Delta 20 and Fujinon lenses?
Okay... there's two possible questions that you might be asking, so I'm going to answer both of them as well as I can. 🙂
One question is if it is optically possible, and the second possible question is if/where lenses are available for purchase.
Optically possible, I believe so. I'm still very unfamiliar as to how projection lenses work (other than they do), but going by what I understand of them at the moment, I think it is possible to shrink a screen and project through it.
As for where lenses are available for purchase, you'll need a positive-focal length (convex) lens and a negative-focal length (concave) lens. The convex lens needs to be as large (or larger) than the screen you're trying to image, while the concave lens only needs to be a little bigger than your projection lens.
The largest convex lens I found was a 20" on E-Bay, and I'm still kicking myself for not buying it. As for readily-available lenses, the largest surplus convex lens (that I've found) is 7 1/2" from Surplus Shed. As for bigger than that, your best bet is to use a fresnel lens. Either get one out of an old OHP, or buy a full-page magnifier from 3DLens.
As for concave lenses, Surplus Shed is great for them too. Just try to match to focal lengths of the two lenses.
Here's an image that shows the setup I'm trying to use to shrink a 5.7" panel down to 4.5"
Keep the wheels of imagination turning!
--Clint
One question is if it is optically possible, and the second possible question is if/where lenses are available for purchase.
Optically possible, I believe so. I'm still very unfamiliar as to how projection lenses work (other than they do), but going by what I understand of them at the moment, I think it is possible to shrink a screen and project through it.
As for where lenses are available for purchase, you'll need a positive-focal length (convex) lens and a negative-focal length (concave) lens. The convex lens needs to be as large (or larger) than the screen you're trying to image, while the concave lens only needs to be a little bigger than your projection lens.
The largest convex lens I found was a 20" on E-Bay, and I'm still kicking myself for not buying it. As for readily-available lenses, the largest surplus convex lens (that I've found) is 7 1/2" from Surplus Shed. As for bigger than that, your best bet is to use a fresnel lens. Either get one out of an old OHP, or buy a full-page magnifier from 3DLens.
As for concave lenses, Surplus Shed is great for them too. Just try to match to focal lengths of the two lenses.
Here's an image that shows the setup I'm trying to use to shrink a 5.7" panel down to 4.5"
Keep the wheels of imagination turning!
--Clint
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Other than the size of the box, is there an advantage to doing this? What's wrong with using a high quality fresnel (like one from an OHP). Does having the projector lens further away from a large panel degrade the picture? This is one thing I've never been clear on.
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