In this issue
Issue #9 January 31, 2013 Jan 31, 2013 Jan 31
Issue #24 August 29, 2013 Aug 29, 2013 Aug 29
Issue #1 October 11, 2012 Oct 11, 2012 Oct 11
From Issue #9 January 31, 2013

Light Motif

A pinhole lens cap finally brings infinite focus and undistorted images to digital cameras.

By David Erik Nelson Twitter icon 

Justin Lundquist was watching TV in 2009 and saw a commercial for one of the first cameras built around the new Olympus/Panasonic “Micro Four Thirds” system. These are high-end digital cameras with interchangeable lenses, and are similar to digital single-lens reflex (DSLR) designs, which show precisely through the viewfinder what the camera captures via its lens.

The design goal with Micro 4/3 was to make a professional camera significantly more compact than any DSLR. What got Lundquist on the phone to his soon-to-be business partner — another Chicago-based photographer, Ben Syverson — was a word that probably didn’t impress anyone else watching that ad: “mirrorless.”

In order to shrink the camera body, Olympus/Panasonic did away with the angled reflex mirror at the heart of any high-quality camera, which allows a shooter to see the lens’s view through a tiny viewfinder. Because the design had a compact camera body and no mirror in the way, Syverson and Lundquist (who happens to be my brother-in-law) realized that they could remove the lens entirely and place a usable pinhole within a few millimeters of the camera’s CCD sensor.

Lundquist, a freelance photographer, has experimented with pinhole cameras for decades. The mirrorless guts of the Micro 4/3 allowed him to finally see beyond the necessity of hacking together his own little digital pinhole camera: He could offer a pinhole add-on to an existing body. The Pinwide, a “pinhole cap,” is the result. It transforms any Micro 4/3 camera into an honest-to-god ultra-wide-angle digital pinhole point-and-shoot.

A super brief foray into physics

A lens creates a sharp image by gathering photons and directing them toward its focal point. Collecting more light reduces exposure times and noise, creates brighter images, and increases detail. But a lens bends the light it gathers; the image it casts is not true to the object. The most obvious example of this is the barrel distortion created by a wide-angle lens.

Strong distortion from a fisheye lens. Photo by Wade Patrick Brooks.

You and I both know that no architect designed a roofline with that curve, and no masons tried to build it that way. This image is grossly distorted, but every image coming through a lens has at least subtle distortions corrected by optics and electronics.

A pinhole camera creates no such distortion because it never alters the path of any photon. Instead, it sharpens an image by massively reducing the number of photons that reach the image plane. Blurriness, in part, is caused by a “point-to-patch” correlation between object and image, where photons striking a given point on the object scatter at slightly different angles and thus strike over an area of the image plane, rather than at one point. By blocking these stray photons, the pinhole brings us closer to an ideal point-to-point correlation between object and image.

The closer you bring a pinhole to the sensor, the smaller it can be. A smaller pinhole blocks more stray photons, and thus yields a sharper image. Shorter distances between pinhole and sensor yield a wider viewing angle, because the entire cone of light cast by the pinhole falls onto the tiny CCD sensor, which has about half the area of a US postage stamp. The result is a super-wide-angle field of view with no lens distortion.

Go build a camera

It’s not hard to make a simple non-mechanical, non-digital pinhole camera. Grab a cardboard box for its body. An oatmeal canister or other tube is good, because you want it lightproof, and any joint is an opportunity for a leak. While you’re digging through the recycling bin, keep an eye out for an old pie tin or soda can.

Cut a small square hole in the side of your would-be camera body, roughly midway down the length of the tube. Don’t worry about making it perfect. This isn’t rocket science; it’s photography.

Spray-paint your box and its lid matte black, inside and out. If the lid or bottom is translucent, back it with a circle of thicker cardboard or plastic before painting. Once that paint dries, you’re just a few minutes away from taking pictures. Cut a piece of aluminum a half inch or so bigger than your square hole. Drill a hole in its center with a pin, then tape that little square of aluminum over your tube’s little square hole. Electrical tape is handy here; you want this to be light tight.

Want to take a picture? That’s where things are trickier today than once upon a time when Kodak was solvent and every school or rec center had a fully stocked darkroom. Those days are gone, but if you have access to a darkroom, then you’re going to go into that darkroom, slide a piece of photo paper into the back of the tube, seal it up, cover your pinhole with your thumb, and head outside. Find something well-lit that you want to photograph, point your camera in its general direction, and remove your thumb for a few dozen seconds. Stay still! Don’t even breathe!

Cover that hole back up, head back to the darkroom, pull out the paper, develop it, and — pow! You’ve got a negative version of what you photographed. Want a positive version (that is, one where the shadows are black and the light is white)? Clamp another sheet of photosensitive paper on top of your negative image, expose them to really bright light for a good long while, and then develop that second paper. Voilà!

Even a pinhole evangelist like my brother-in-law acknowledges that this is a pain in the ass.

“The reason it sucks is because you’re stuck being near a darkroom, because it’s a one-shot thing: You put one piece of 5-by-7 [inch photographic] paper into the oatmeal can, you go out somewhere relatively close, you go back into the darkroom and process it and see how it looks. If you want to take another picture, you load it while you’re in the darkroom and go out again. So it’s simple to build and to use, but it’s not practical for taking a bunch of shots out and about.”

Despite the pain-in-the-assery of it all, pinhole cameras offer certain advantages that keep us coming back. First and foremost is that a pinhole camera has no lens, which means an infinite depth of field with no lens distortion. In other words, everything from the pinhole to infinity is equally in focus. Set your camera in a meadow and take a picture of the clear sky; each blade of grass is just as sharp as the moon.

But the most readily recognized hallmark of pinhole photography is the natural vignetting. This is the fairly pronounced circular light falloff from a bright center to shadowed edges.

A dearth of commercial pinhole gear

Despite the enduring allure of pinhole, no decent pinhole analog, digital camera, nor accessory has ever come to market. This isn’t to say that there’s been no attempt at pro-grade pinhole gear, just that the results have been disappointing.

Despite their complete lack of experience in engineering, industrial design, or physics, Lundquist and Syverson immediately realized why: most pre-digital interchangeable-lens SLRs and their electronic DSLR descendants use the method (developed in the late 19th century) of allowing a single objective lens to serve as both the viewfinder and the “taking” lens.1

SLRs and DSLRs have a flip-up mirror mounted just behind the lens. When you squint through the viewfinder, that mirror is resting at a 45-degree angle between the lens and your eyepiece, which has its own fixed 45-degree-angle mirror — it’s like a periscope — beaming whatever the camera sees directly to your eye. When you press the shutter release, the little mirror flips up out of the way and the shutter cycles, exposing the film. Then the mirror drops back into place and you’re back to viewing. DSLRs may use an image sensor instead of film, but they otherwise maintain all of an old film SLR’s internal mechanics.

This clever arrangement of flip-up mirrors is fine if you’re using a lens, but replacing the lens with a pinhole proves entirely unworkable: The reflex mirror forces a huge gap between the pinhole aperture and the sensor (or film). At that distance, the pinhole itself must be made larger to allow more light to pass through. The result is a blurrier image that overspills the sensor, and is thus cropped square. This is totally unacceptable to guys who really care about pinhole.

Going pinwide

But making a workable product — one that performs consistently — is a far cry from hacking something together from recyclables and tape. The real challenge is the pinhole itself. First of all, that hole has to be as smooth and round as possible. Additionally, you want the material surrounding the pinhole to be thinner than the diameter of the hole — otherwise, light bouncing off the interior surface of the passage scatters unpredictably on the image plane, blurring the picture. The Pinwide’s design calls for a pinhole less than a third the size of a period on a printed page; you aren’t going to get that in molded plastic, or even by popping pins through pie tins.

Committed non-digital pinhole hobbyists buy thin metal foil that’s been custom micro-drilled, or even laser-drilled. While this can have good results photographically, the cost is prohibitive: at $30 a pop, using either method would have doubled the price of the Pinwide.

Then Lundquist and Syverson discovered the chemically etched aperture grids made for electron microscopes. These are minuscule holes burned through tiny circles of ultra-thin vapor-deposited foil. They’re produced using an industrial process and can be bought only in bulk; totally impractical for a lone hobbyist monkeying around on his own, but a fraction of the cost of a manually drilled pinhole aperture once you do the per-unit math. And they take awesome pictures.

Signal and noise

As our tools become cheaper, cleaner, and crisper, we tend to grow nostalgic for the old “noisy” things of the past — the roar of a guitar overdriving an underpowered amp, the smeary Polaroid colors imitated by Instagram filters. I suggest to Lundquist that the Pinwide, which introduces the flat, wide angle and vignetting of yore to high-resolution digital photography, is one more example of our tendency to make yesterday’s noise into today’s signal.

Lundquist sets me straight: Yes, the software-based “pinhole” effects take a clear digital image — albeit one distorted by a glass lens — and further muck it up with filters, masks, and circular cropping. But the Pinwide is “just showing more of the image through to the dark edge where it’s falling off, instead of cropping out what’s naturally there.” Any other camera configuration, from a junkshop toy 35mm point-and-shoot to a $6000 Canon EOS-1D X with all the trimmings, discards much of the large, circular image captured by its lens, preserving only the sharp, bright square at the center.

An actual pinhole photograph, analog or digital, is “a straight image that’s being captured with just the light and the sensor” and nothing intervening. All you see is what’s there, and you see it more and more clearly as you block out more and more of that stray light.

Pinhole photos by Justin Lundquist.

  1. Amateur analog cameras, on the other hand, usually use a separate low-quality lens for the viewfinder — a sorta crappy version of the classic “twin-lens reflex” design — while cheaper digital cameras use either this approach or low-resolution electronic viewfinders that pull an image from the CCD. 

David Erik Nelson keeps house in Ann Arbor, Michigan, with his wife, toy poodle, and two human children. His writing includes the geeky craft book Snip, Burn, Solder, Shred, a monthly opinion column in the Ann Arbor Chronicle, and short stories that have appeared in magazines like Asimov's, anthologies like Steampunk II: Steampunk Reloaded, and sprinkled across the Web. His novella “Tucker Teaches the Clockies to Copulate” is now available as an illustrated e-book for Kindle (and basically everything else).

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