Advantages of, and Resources for Pinhole Cameras
Presented to the Milpitas Camera Club
by S.R. Hinrichs
Tuesday, August 10, 2004
© 2004 S.R. Hinrichs
This manuscript may be used for instructional purposes only.
Manuscript may not be used for commercial purposes without permission of author.
A little history
The Pinhole: Third imaging system invented by man
1.) The window: Invented about a half a million years ago.
2.) The plane mirror: Invented just after the Bronze Age, 6,000 years ago.
· The Greeks knew about the image-making properties of the pinhole.
· Alhazan (Al-Haytham) 1,000 years ago, explained the theories behind the pinhole, the image inversion, and the theory of the lens to which he ascribed the Arabic word for lentil to describe the shape of the lens of the human eye.
· Leonardo DaVinci may have used the pinhole as a tool to study perspective in the 1500s.
· Della Porta reinvented the pinhole camera and probably coined the term “Camera obscura.”
· Pinholes have practical applications in focusing xrays and other outside-the-visible spectrum radiation.
· The Pinhole Renaissance: pinhole photography underwent a resurgence of popularity, in the 1970s, 1980s and 1990s, re-establishing itself as a purely artistic endeavor.
The nature of pinhole images
Advantages that pinholes have over lenses:
(Providing that crystal-clarity is not an issue!)
1.) Great depth of field-relative clarity from a few centimeters to infinity
2.) Free of any linear distortion-lenses distort, pinholes don’t
3.) Wide angular field-the closer to the film plane the wider the field of view.
Other properties: (That contribute to the surreal properties of pinhole images.)
4.) Dilation of time-time exposures in broad daylight: most moving objects are motion blurred, smeared or disappear entirely.
5.) Concentric drop-off of brightness-lending more emphasis to the center of the image. (See diagram A)
6.) Overall softness-in both focus and tonal contrast.
Subject matter/resources for pinhole photographers:
The scenes you choose should have great depth. A vanishing point and elements in perspective make for dynamic images. Flat subjects should be avoided because they produce less-than-exciting pinhole images.
Scenes should have more tonal or color contrast in order to compensate for the softness of the pinhole image. Subjects with great contrast are rendered well by the pinhole.
The drawbacks of the pinhole image forces you to become a better photographer and compel you use the principals of composition to craft a better image. Using a pinhole camera forces you to become a better photographer.
For examples of what a pinhole camera does, visit the following Web sites:
Many pinhole images from around the world
See pinhole images from around the world, taken on World Pinhole Photography Day 2001, 2002, 2003 and April 25, 2004. Perhaps you would like to participate in the 2005 event.
Other sites: www.pinholevisions.org
Building cameras: www.zeroimage.com
Exposure guides: www.mrpinhole.com/calcpinh.php (has an interactive exposure calculator)
For the gear-heads: pinhole.stanford.edu/pinholemath.htm
Other types of cameras: http://www.abelsonscopeworks.com/cameras/turret.htm
Commercial sites: http://www.paintcancamera.com
Various types of pinhole cameras
· Simple box camera-round, square, triangular etc.
· Conversions for roll film-35mm, 120 roll film cameras or cheap point-and-shoot cameras. Enables you to use the existing roll film mechanism in your 35mm camera body. Plates can be made to fit over lens mounts or lenses can be removed and replaced with a pinhole plate or zone plate insert.
· Sheet film conversions-Old fashioned cameras with backs that accept 4 x 5 sheet film holders or Polaroid backs make ideal pinhole cameras. Bellows allow the angle of view to be narrowed or widened.
· Novelty-hollowed out fruits and vegetables, cowboy boots, vans, motel rooms, film canisters, human hand cameras-the sky’s the limit!
· Multiple apertures-bug’s eye view cameras, turrets, multiple holes, 360-degree views etc.
· Zone plate/light sieve cameras-Zone plates and light sieves are arrays that focus light like a lens, but have no optical focusing lens (they were originally developed to focus x-rays). Zone plates require focusing. (See Diagram E)
· The next frontier-highly specialized types of pinhole/slit imaging.
Omniscope and other anamorphic cameras-produce very distorted 360-degree panoramic images.
Wide angle/panoramic-produced with multiple pinholes.
Bugs-eye camera-uses arrays of pinholes to simulate an insect’s compound eye.
Slit cameras-various shaped apertures on litho film.
Building a pinhole camera requires you to consider several features:
1.) Focal length
2.) Choice of light sensitive media-roll film, sheet film, photo paper, Polaroid film, video matrix etc.
3.) Film plane orientation-parallel with lens plate, convex, concave or twisted
4.) Size and shape of pinhole-perfectly round, slit, bug-eye arrays, multiple holes, turret, light sieve or zone plate
5.) Film handling-sheets or roll film (manual or mechanical)
6.) Size of camera chamber-larger cameras with optimum-sized apertures have more image “meat” (pixels) than smaller cameras with optimum-sized apertures.
7.) Materials-durability, lightness, aesthetics, buildability etc.
8.) Purpose-Spy cam, art cam- …or what?
The focal length
· Focal length is the distance from the pinhole to the film plane.
· Focal length and pinhole diameter determine exposure factors for the camera. (See Diagram B and Chart C)
· A given focal length has a corresponding, optimum hole size that will produce the best image qualities.
· A longer focal length increases the exposure time required and, conversely, pinholes closer to the film plane require less exposure time.
· Holes closer to the film plane produce greater wide-angle effects and holes further away produce telephoto effects.
· The smaller the hole the longer the exposure time required.
· The smaller and rounder the pinhole the sharper the image. I use a #13 needle hole with good results-I’ve yet to find a #15 needle. You can also order micro-drilled and laser-drilled pinholes from several commercial sources. (See Diagram D)
· Materials: Aluminum foil works well, but is fragile. For a more durable hole you can use brass shim stock. If your pinhole matrix is too thick it will adversely affect the image-forming capabilities.
· Distorting the shape of the pinhole will also distort the image. Slits, oblong holes, star-shaped holes, lines, designs, zone plates and photon sieves-all produce different types of images. (See Diagram E)
A formula to arrive at the optimum focal length
A = Square root of 55 X F
A = aperture diameter in thousandths of an inch
F = focal length in inches (55 x F)
(There are probably at least 50 of these formulas in use.)
…Another formula for image clarity
This is a formula developed by nineteenth-century French photographer M. Jules Combe, in 1899, to achieve a high degree of sharpness:
A x A x 4 divided by 127 = camera extension in inches (focal length)
A = aperture diameter in inches
For instance: A #10 needle has a diameter of 18 thousandths of an inch (18 x 18 x 4 divided by 127 = 10.2 inches). Therefore, for optimum sharpness with a #10 needle hole, make a camera with a chamber 10.2 inches in depth.
Developing an exposure guide
· Determine pinhole diameter
· Measure focal length
· Calculate equivalent f. stop-Use formulas, charts or by experimentation.
· Plug numbers into exposure chart (See Chart F)
· Factor in reciprocity failure factor-add time for longer exposures
Plug in your numbers to the exposure formula: Shutter speed=1/ISO rating of film/matrix @ f.16. When f. 16 is factored down to the equivalent f-stop of the pinhole diameter then the time side of the formula should give you a calculation in seconds or minutes, depending upon the lighting conditions and the focal length of your camera.