making a camera obscura with inverted image

Discussion in 'Alternative Techniques & Photo Gallery' started by harriet, Aug 16, 2008.

  1. harriet

    harriet TPF Noob!

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    hello

    am making a camera obscura in a shed.

    does anyone have any ideas about inverting a wall based hole image? i was thinking about pentaprism or a makeshift pentamirror, does anyone have any thoughts, advice or experience?

    thanks :)
     
  2. Bifurcator

    Bifurcator TPF Noob!

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    You're making a dark room? And you want to do what?
     
  3. Steph

    Steph No longer a newbie, moving up!

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    A camera obscura is a dark room with a small hole in a wall, which is going to produce an upside down image of the outside world (a bit like a pinhole camera). I think the OP is asking ways to get the image the right way up.
     
  4. Helen B

    Helen B TPF Noob!

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    They often have a lens and mirror arrangement in a little turret in the roof, so the image is projected downwards onto a table, and viewed the right way up.

    Where the projection is from a hole (with or without lens) in one wall onto an opposite wall, as in this case, it is more difficult to arrange for an erect image. The image is naturally vertically inverted (upside down), but because you are looking at it from the 'wrong side' it is correct in terms of left and right when viewed from inside the room (laterally correct).

    You could project an erect (ie up is up) image with one lens and three front-surface mirrors, in a vertical arrangement, that is also laterally correct when viewed from inside the room. I'll sketch an option out later if I get the chance: first mirror is above a lens (the optical axis of the lens is vertical) sending the incoming rays downwards to the lens, second is below the lens sending the rays upwards to the third mirror that turns the rays towards the wall.

    Best,
    Helen
     
  5. Bifurcator

    Bifurcator TPF Noob!

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    Wow, a pinhole camera the size of an entire shed. :D Kewl! What's the purpose?
     
  6. Helen B

    Helen B TPF Noob!

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    Well you could do it with an aircraft hangar.

    Another link.

    From her other posts I guess that she wants to make large prints directly inside the camera obscura. Most of the time the reversed nature of the print is accepted (ie when the print is turned the right way up it gets laterally reversed).

    Best,
    Helen
     
    Last edited: Aug 18, 2008
  7. harriet

    harriet TPF Noob!

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    helen- to clarify i want to make it a live experience with the hole in the wall- so people are inside the shed which is why i want to invert it- a sketch would be great of your written idea if possible- is this like the pentamirror? can i give an email address?

    thanks for the hangar link- amazing stuff :)
     
  8. tasman

    tasman TPF Noob!

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    My front door does this through the peep hole. I see an image of the house next door projected on the wall and it is right side up. So you might want to try it.
     
  9. windrivermaiden

    windrivermaiden TPF Noob!

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    our window blinds do as well, the little holes in the top act as lens. I never thought that multiple holes would work and the room doesnt have to even be that dark. It is so cool.
     

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