Cylindrical Perspective Window

The cylindrical perspective window is a drawing tool which allows a used to trace the local landscape in near perfect perspective. As another Exploratorium prototype, it based off the museum's existing perspective window. The original is a flat window to draw on with a fixed eyepiece, my version uses a curves sheet of lexan instead of flat glass which makes the entire drawing surface the same distance from the eye.  Optimally one would use a spherical window so all points were equidistant from the eye.  However, because this window is for drawing landscapes in the far field, most of the drawing happens in the middle of the window so a cylindrical window makes decent approximation of a sphere as long as you do not draw at the upper of lower edges of the window.

I decided to use a slot made of laser cut acrylic with a chin rest instead of a round hole for the view port as it avoids the need to adjust the height of the eyepiece. The rest of the perspective window is made of plywood cut on a cnc router, maple dowels and the legs are made from some cardboard tubes from butcher paper rolls. The window structure has a series of plugs that fit into the cardboard legs holding them on securely but also allowing legs a base plate to be removed for easy storage.    

 The curved window widens area you can draw on without distorting the image horizontally, making very wide angle drawings possible.

Here is an image of a drawing taken from above and to the left of the original eye position.