CoffeeCam: a Shutter for Large Format Pinhole Can Cameras

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Making a pinhole camera from a can or an oatmeal box is a traditional exercise in beginning photography (see links below). Usually, the cameras produced are perfectly workable, but festooned with abundant gaffer's tape, and use a cumbersome flap of tape as a rudimentary shutter. This is a shutter and pinhole clamp designed to be fastened onto a small coffee can (espresso-sized) or similar. Used with sheet film or photographic paper, this kind of pinhole camera needs to be loaded with fresh film or paper (in the dark!) for every exposure Additionally, the shutter assembly can be 3D printed to mount on a flat surface, like a cigar box, OR on the lid of the can for a classic anamorphic pinhole camera. Better yet, put two shutters on your container for some versatility! Include is a script to generate tripod mounts for both flat and curved sides. As with the shutter assy, change the diameter parameter to fit your can. The TeaCam only needs one radiused mount, and is intended for anamorphic photography exclusively. . The OpenSCAD script 'coffeecam.scad' is easy to modify for your chosen cylindrical container or flat-sided boxes. The OpenSCAD script 'coffeecam_tripod.scad' renders a pair of tripod mounts, one flat and one radiused for your can's diameter. [Jana_Obscura] is a local photographer who has been testing my camera designs. Here's her latest shoot with the CoffeeCamHere's more from [EspressoBuzz], another local pinhole photographer. Both [Jana_Obscura] and [EspressoBuzz] have acted as proofing editors on the P6*6 user manual as well. ======== Addenda ======== Added TeaCam STLs and .scad files for smaller diameter tea tins (~66mm), allowing for clearance of shutter blade and bottom rim, and greater contact area for bonding tripod mount. Republic Of Tea tins have a nice, air-tight snap fit lid and ample room for 4X5 film/paper. ========= LYNX =========Making Oatmeal Box Pinhole Cameras Kodak: Making a pinhole camera PinholeDesigner (windows) Drill Your Own Precision Pinhole Apertures ATTENTION This work is licensed under the Creative Commons - Attribution - Non-Commercial license. This license applies only to the files and documents available for download from the Thing Files section of this Thing.All other related content (photographs, videos, and verbiage such as contained in "Description" or "Instructions" ) are excluded from this license. with all rights reserved, unless specifically available for download This notice constitutes a clarification, not a change, to licensing for this design. Instructions Pinhole cameras are often regarded as random and unpredictable. This is a fallacy - the quality and consistency of your photographs are directly related to certain design details. Most importantly, the *focal distance* of the film from the aperture (pinhole), and the diameter of that pinhole. Combined, these two factors determine the "speed" or *f-number* of your pinhole camera. For any given wavelength of light and focal distance there is an optimal pinhole diameter. Guessing at these values will give you unpredictable results. For the pictured pinhole camera, made from an ILLY espresso can, a curved sheet of 4X5 film will lie against the back of the can, which is 91 mm in diameter. The film can be oriented either vertically or horizontally, and, in either case, the lateral edges will be closer to the pinhole, and receive relatively more light during an exposure. Using a nominal 90mm, the optimal pinhole diameter is 0.40 mm. There are several alternate constants used to calculate an "optimal pinhole diameter". They will all be in the ball park. [F-number](http://en.wikipedia.org/wiki/F-number) for any camera is calculated as *focal length* / *aperture diameter*, or 90 / 0.40, yielding an f-number of 225, written as f/225. This relates directly to how long an exposure must be for a given film speed (and *reciprocity failure*) and lighting conditions. If make an exposure using the pinhole on top of the camera, such that light is falling on the film at a low angle, you will have significantly different F-numbers as the distance from the aperture increases. Using the ILLY coffee can, the top of the film, closest to the pinhole, has a speed of f/137, the middle f/212, and the bottom f325. These numbers are approximate and assume a vertical orientation of 4X5 sheet film. In addition to the distorted perspective such an _anamorphic_ camera creates, the potential exists for significant differences in exposure from one edge of the film to the opposite. This can be used to artistic effect or mediated by calculating your exposures with the medium or average F-number. This will necessitate some experimentation by the photographer. For a couple of beautiful anamorphic photos, see [Jana_Obscura's test shots with the CoffeeCam](http://www.jana-obscura.com/blog/2014/3/4/the-schlems-coffeecam) It is beyond the scope of this explanation to go into greater detail, but the following links are helpful: [PinholeDesigner, a windows application](http://www.pinhole.cz/en/pinholedesigner/) [Mr. Pinhole](http://www.mrpinhole.com/exposure.php) [Stanford Pinhole Calculator](http://pinhole.stanford.edu/phcalc3.htm) There are several important parameters in the OpenSCAD script: "curved" - makes the shutter mount curved or flat "can_d" - diameter of the cylinder the shutter will be mounted on "fudge" - a fit-tolerance setting for the shutter. The included STLs use a fudge of 1.08, or 108%, which is probably unnecessarily big. My prototype shutter is looser than I would like. The coffeecam.scad script has been updated to a more satisfactory 103% tolerance. The STL files persist in their looseness until which time I re-render them. This is the most complicated OpenSCAD script I have written. Among other things, there are different *translate* commands (in the "Top Level code" section) that will either lay out a plate or an assembled shutter for examination. Just change the appropriate commenting. I learned a few things about "componentized design" that I plan to use in the 6X9 version of the P6, predictably to be named the P6*9. I have measured diameters for the following containers: illy espresso can - 91 mm Lavazza espresso can - 109 mm McCanns Irish Oats - 114 mm Quaker Oats - 128 mm You will need to paint the inside of your can flat black. I drilled a hole 2 1/2 inches from the inside bottom edge (for 4X5 film), and used a "nibbler" tool to square it up. Scissors or a carefully wielded knife would work too. You could simple make a careful "X" in the can and bend the triangles over (inside). The shutter covers the hole you make, so don't despair if the hole in your can is a little rough. You may want to wrap the joint at the lid with a turn of gaffer's or electrical tape for light-proofing. I used a sheet of sandpaper around the coffee can as a form to smooth the mounting surface a bit. I then mounted it with liberal superglue before drilling the 3mm holes through the can. For best results, a gap-filling adhesive should be used for light-tightness. I have had good results with JB Weld, which I used to mount the tripod adapters. There is a lacquer on the outside of the ILLY can, so some careful sanding will help it stick. (I have repaired popped-off printed parts with super glue between the can and JB Weld) Bolting the shutter assembly allows you to disassemble to replace the pinhole if you want to experiment. If you're using a cardboard box (oatmeal or other), you might want to be more thorough with your gluing for mechanical strength. The film needs to be loaded and unloaded in a dark environment or a *changing bag* (for persons with large hands, a dreadful, claustrophobic device). I probably won't make any photographs with this camera until I have my darkroom set up again. If and when I do, I will post a link to the photos. I haven't planned to make this a *Customizer* app, but if that would be helpful to you, let me know in the comments. Additionally, let me know if you would be interested in purchasing a custom shutter and tripod adapters for your chosen container through my store at Tindie.com.