Make the Sky in a Room

Imagine viewing the spectacle of dawn and sunrise while remaining in your bed. During a storm, lightning will seem to fall in your room, so that you want to hide under the covers to escape the storm. You will see street lamps far away, and some nights, if your window is facing the right direction, you will see the moon run among the clouds. It is possible to bring the beauty of the outdoors right into your room by simply mounting a lens on the bedroom window, and admiring the outside scene projected on a wall of your bedroom. Note that the image will be inverted.

Steps

  1. Ask the optician to reduce a lens diameter so that it can settle down precisely in the bottom of a 24x36 film container, as shown in figure 2. This work is commonly performed by opticians to fit lenses into eyeglass frames, therefore do not be afraid to ask that to the optician. After this operation, make a case for your lens as that shown in figure 2.
  2. Buy a shutter and saw it to the right width, then insert it into the window opening as shown in figure 3. The light must pass through the lens only. The shutter has to be fully opaque, to completely shut out the light, and must slide along two lateral guides. Make sure to open a hole in the tissue to allow light to enter the room, but take care to close off every other light source.
  3. Mount the case with the lens in the hole made in a wooden board as in figure 4. Place the board on the window-sill and pull down the shutter so that no light filters among the slats. The board must be shorter than the window's width in order to be put into place, so as to close the remaining opening also.
  4. Make two coaxial holes of different diameter. The window slats have two walls, one inside, the other outside. Make the internal hole with an annular drill. Make the external hole with a circular path of little holes, removing the central part, and finishing with a half-round file.
    • When you finish working the hole, place some glue and insert the lens case into the slat.

Tips

  • If you cannot find this type of shutter, buy an anti-mosquito roller web instead. Replace the web with a black plasticized tissue, or a black plastic strong film.
  • The lens will project the image on every wall of the room, floor and ceiling. The only wall excluded is that of the window. The image will be distinct only on the wall opposite to the window. The other walls will send reflected light which will lower the contrast of the principal image.
  • The eyeglass industry is the only one that measures focal lengths as diopters. So, when you go to the optician to buy the lens for this experiment, he will ask you how much power, or diopters, you want it. This simple formula allows you to pass from the focal length to the diopters:

    • D = 1/FL
      • where:FL = focal length of the lens (expressed in meters)
      • a converging lens of half a meter of focal length has a power of +2 diopters. In fact: D = 1/0,5 = +2
      • a converging lens of {{safesubst:#invoke:convert|convert}} of focal length has a power of +0.25 diopters. In fact: D = 1/4 = +0,25
      • Place the sign "+" before the power of a converging lens and the sign "-" before the power of a diverging lens. For this experiment you need a converging lens.

Warnings

  • For more detailed information, please read the source of this article, before and while attempting to create this: The Sky in a Room

Things You'll Need

  • Film canister (24 x 36" / 60 cm x 91 cm)
  • A converging lens
  • Shutter (opaque, wooden) / anti-mosquito roller web
  • Saw
  • Cutting implements

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Sources and Citations

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