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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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    • [โ€“] 8 points 8 months ago* (last edited 8 months ago)

    There are prism glasses for reading etc while lying flat in bed, whether you're lazy (they're sometimes called lazy glasses) or in traction. The prisms point the opposite way from climbing prism glasses.

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    [โ€“] 1 point 8 months ago

    Federal Prism

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