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Pinhole Panorama camera idea


EricBall

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Roughly based on: http://blog.makezine.com/archive/2010/03/weekend-project-pinhole-panoramic-c.html

 

The design point is to make a 120 roll film cyclindrical panorama camera. My original idea was to make one with a 90 degree vertical field of view & 135 degree horizontal FoV, with the idea that a full 360 degrees would be covered in 3 shots. But then I got to thinking about adding a zenith shot (which would be easy if the depth of the camera was half the height), so up'd it to 105 degrees vertical FoV.

 

However, then I read a post which mentioned that the effective F-number of a wide angle pinhole camera falls off at the edges due to the greater distance from the pinhole. D'oh! 1/cos(105/2) = 1.62, which is almost 1.5 f-stops. Thus I decided to go back to just 90 degrees vertical FoV (1 f-stop) and not worry about the zenith.

 

From a design standpoint, unlike the Make camera, I decided to make the body interior the same height as the spool (65.5mm). The film guide then is pair of 5mm thick 28mm radius semicircles glued to the top and bottom. Roller pins at the front guide the film from the spools around the guides. Tension on the spools holds the film against the guide.

 

pinhole.zip - updated, with plans for whole camera

 

The lens is a laser cut pinhole 0.2 mm in diameter (aka 200 micron), in as thin of a material as possible. (Turns out the laser cut pinhole would be $30. So I'll start with making my own in some aluminum foil.

 

The result is a 56mm x 88mm frame covering the full 180 degrees (well, less than that due to both the guide pins and pinhole material thickness/fringing). Update - should be ~165 degrees.

 

Assuming 5mm material the camera dimensions should be 120mm x 80mm x 40mm, or 4.7" x 3.2" x 1.6", which seems very, very small. Update: 137.5mm x 45mm x 78mm according to current plans.

 

ToDos:

1. Determine possible 5mm construction materials. Done - black on black foam core board, 5mm thick (perfect), and $10 for the sheet.

2. Get a couple of 120 film spools, find out who sells & develops 120 film. Done - Was tipped off about a local camera show and picked up 3 rolls of color negative for $3 and 5 rolls of color slide (aka "reversal") for $10 (expired, but good enough for what I want to do). I've unrolled one of the rolls so I now have an empty spool.

3. Work out the miscellaneous hardware - guide pins, spool pins & winders. Update: pencils (dia 7mm) for guide pins, PC screws for spool pins, bent wire for winders.

4. Pinhole & viewing window. Update: aluminum foil for pinhole, exposed negative for viewing window.

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Sounds like fun! I cheated and bought a pinhole "lens" for my DSLR. If I recall correctly, it gives about 45 degrees horizontally. Because of limitations of the sensor and the size of the hole, though, I only get an effective resolution of about a 1MB, if my calculations and memory are correct.

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