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Could a prism make it so you could read a flat led screen at ~eye level? (slrpnk.net)
submitted 8 months ago by to c/nostupidquestions@lemmy.ca
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[โ€“] 14 points 8 months ago (2 children)

yes, in fact modern projectors use a 'short throw' technique like this so that the projector lens part only needs to be inches from the screen above to lay out a very large, flat display below... kinda of the opposite of your image

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  • [โ€“] 5 points 8 months ago* (1 child)

    "snorkel lenses" look ridiculous on large projectors.
    https://epson.com/Accessories/Projector-Accessories/ELPLX02-Ultra-Short-throw-Lens/p/V12H004X02

    Goes in the front like a normal lens, shoots backwards like a cursed lens.

    The problem with short-throw lenses is that they will exacerbate any geometry issues. So aligning them is hard. And ANY tiny little non-planer issue with the screen surface gets massively multiplied.
    You can get away with a lot of issues using long lenses. Short lenses are a pain.

    ETA:
    Linked is a 0.35 ratio lense.
    So for every 0.35m from the screen, it will project a 1m wide screen.
    0.7m away? 2m screen. 1.25m away? 5m wide screen.
    3.5m away? 10m wide screen.

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