What is pinhole photography? Well. Like with any other type of photography, one will need a camera, but one without a lens. Pinhole Photography is lensless photography! Before we go there however, let me give you a brief history. That will explain a lot.
The Frenchman Niepce is credited with the invention of photography and like with many inventions, it was a process of trial and error, but all of Niepce’s efforts were based on two previous discoveries. The discovery in 1727 by the German professor Johann Schultz that the mineral silver salt darkens by light and not by heat and the Camera Obscura. We leave the minerals alone for now. They are not relevant for this essay. The Camera Obscura however, is the centerpiece! Nobody knows for sure when the Camera Obscura was invented, but some historians trace it back all the way to China in the 4th century B.C. The name means “dark chamber” in Latin and is basically a large projector. What they did was, they darkened a small room with light admitting through a single tiny hole on one side and a wall of some sort on the opposite side with the result that an inverted image of the outside scene was casted on the opposite wall. Later Camera Obscuras became a lot smaller and even portable. They were used by scientists for scientific purposes and by some artists, who used them to trace a scene, like a landscape, on a piece of paper. Some called that cheating. Some experts in today’s day and age even accused Johan Vermeer of using one. Most experts though think he didn’t. Nevertheless, the jury is still out on that one. They just can’t understand how he could paint so realistically. Anyway, to create a reasonable sharp projection, the size of the hole had to precisely calculated. More about that later.
A pinhole camera is not any different than a Camera Obscura. Especially not a film-based pinhole camera, which is, like a Camera Obscura, just an empty box with a tiny hole on one side and a medium on the opposite side to capture the projection. It is the simplest camera you can imagine. No lens, usually no viewfinder, no electronics, and no confusing buttons. This empty box could be any lighttight material and could be either rectangular or cylindrical, or even anamorphic. Some purist pinhole photographers make their own cameras from all kinds of things. From used cigar boxes to soup cans. They also come in all film formats, from 35mm to 8 x 10 inch sheet film. Besides film, a light sensitive piece of photographic paper can also be used. People who use an 8 x 10 pinhole camera use that a lot. It is a lot of fun and a heck of a lot cheaper than 8 x 10 sheet film. ($15-$25.00 per sheet in the U.S.) The pinhole cameras I own are all made from wood or plastic of some sort and range in film size from 2 ¼ x 2 ¼ inch to 4 x 5 inch sheet film. I don’t like to use anything smaller than 2 ¼ x 2 ¼ inch. (6 x 6 cm). I have one plastic toy camera that I converted to a pinhole camera. That one has the luxury of a viewfinder. My 4 x 5 inch cameras are homemade by a friend of mine and look just like little bird houses for nesting. Most pinhole photographers have a good collection of cameras, not because they might be hoarders (they might be or not be), but also because for each focal length, you need a separate camera. Medium to extreme wide angle though seems to be the most popular. Theoretically, medium to longer telephoto cameras are also possible, but you would run into technical and practical problems if the focal length gets too long.
There are also digital pinhole cameras that are regular DSR’s or mirrorless digital cameras that use a specialty lens with no glass as a substitute for a real lens or use a homemade device of some sort. We save that for another day. (or not)
Will any size of the pinhole work with any pinhole camera? Can I just drill a little hole in a lighttight box, and I am done? Unfortunately, no. The (pin)hole is the most important part of the camera and needs to be made as precise as possible. The hole sizes vary for each focal length. You can find the focal length by measuring the distance from the hole to the film plane. There are formulas to calculate the ideal diameter of the pinhole. Once you know the focal length and the diameter of the pinhole, you can calculate the aperture or f-stop if you like. You do that by dividing the focal length by the pinhole diameter. For instance, a focal length of 70 mm and a hole diameter of 0.30mm is 70 divided by 0.3, which gives an aperture of f/240. To avoid confusion between the focal length and aperture, focal lens is written with an upper case F and aperture with a lower case f and followed by a forward slash. Even some professional photography websites manage to mess this up, so I thought that a clarification about this might be helpful.
Now, in photography, the smaller the aperture (bigger number), the larger the Depth of Field, which is that section of the image that goes from the nearest part that is in focus up to the furthest part that is in focus. Since f/22 has a much larger Depth of Field than f/1.4 for instance, one would think that with an aperture of f/240, everything in the image would be in focus. Everything from right up to the hole to infinity and, technically speaking, everything is in focus. Everything is in focus, but nothing in the image is sharp. How come? Well, there is a snake hiding in the grass, and that is called diffraction. Even though you can see detail, it is always a little fuzzy. Without getting too technical here, that fuzziness is because light rays bend around flat surfaces and by doing so, the light rays become slightly distorted and are not exactly aligned anymore. This is called diffraction and causes the image to look a little fuzzy. The more accurate and “cleaner” the pinhole is, the less diffraction and the sharper the image will turn out. There are several requirements to obtain this accuracy; first, the material thickness must be as thin as possible, while remaining stiff enough to avoid distortion or crumbling of the foil and the level of accuracy of the pinhole. Not just in the location, but also in how the pinhole is drilled. There are 3 ways you can do that; You can “drill” the hole yourself with a fine needle. This method can give great results but is risky and requires a lot of expertise. Second, you can laser drill the hole, which is probably the most accurate method, but leaves sharp edges that don’t help and might even cause more diffraction in my opinion, and third, chemically etched pinholes, which can also give great results. I have all 3 kinds and to me it seems that the home made and the chemically etched pinholes give overall a better result than a laser. It is difficult to spot the difference between a well-made do it yourself pinhole and a chemically etched pinhole.
On a side note: Diffraction occurs also with normal lenses and becomes on average more noticeable with apertures smaller than f16 or so, depending on the lens. Every lens has an ideal aperture, which is for most modern lenses for DSLR’s or mirrorless around f/11. With pinholes, using a larger or smaller hole size than the ideal hole size will also influence the sharpness in a negative way.
So, now we know the aperture, we can measure the exposure and set the exposure time. With digital photography, there are 3 things that the photographer can change to come to the correct exposure, The ISO, the aperture, and the shutter speed. This is not the case with pinhole photography on film. The ISO (or sensitivity) is determined by the film you are using and fixed (there are some exceptions) and since a pinhole camera has also a fixed aperture, the only thing that is subject to change is the shutter speed. But how on earth do you set the shutter speed? Most pinhole cameras have some sort of mechanism to cover the pinhole to stop light from entering the camera. All mechanical of course. You will have to move this mechanism by hand. Some cameras have an adapter for a mechanical cable release, but it is either way all manual labor.
Keep in mind that the camera has no light meter, so a handheld light meter needs to be used. However, there is no light meter on the market that can measure those small apertures in f/200-f/300 range. This means that whatever shutter speed the light meter came up with any random aperture, needs to be converted to the shutter speed appropriate for the aperture of your pinhole camera. The exposure needs to be recalculated to the shutter speed corresponding to f/240 or whatever the case may be for the camera you are using. Fortunately, there are apps and tables for that. Because of this awfully small aperture, the 1/60 sec. or 1/125 sec. shutter speed you measured can easily turn into 10, 20, 40 seconds exposure or (much) longer and since we work with film, that means that we also need to use a little thing called the Reciprocity Factor. Reciprocity Factor is a time factor that needs to be added to the calculated shutter speed after the conversion to the smaller pinhole aperture. Film becomes less sensitive to light with longer shutter speed and that needs to be compensated for by adding more time. This compensation is called the Reciprocity Factor, which varies greatly from film to film. Fortunately, there are apps and tables for that too. Some apps do both calculations at the same time, so it’s not as bad and complicated as it sounds. Also, many photographers get used to their favorite films, so after a while it becomes second nature. Safest is though to keep those tables on hand.
So, why in the world go through all this trouble for a fuzzy picture, you ask?
A fellow pinhole photographer said it is about the atmosphere. It is not about capturing technically perfect pictures. It is about capturing atmosphere. He is right and to me, the pinhole camera is the perfect tool for that. A pinhole camera is just a box with no settings, buttons, adjustable rings, or adjustable this or that and no distraction. Just the photographer, a box, and the subject.
Sure, calculating the correct shutter speed is a technical thing that needs to be done, but it is done after the fact. After the image is composed as good as you can (remember no viewfinder) and ready to go.
One of the comments I received once about one of my pinhole Everglades images was that the image “Really conveys that Everglades look!”. That was one of the nicest comments I have ever received. Isn’t that what we are all going for? That image where the viewer, the subject, and the photographer all become one?
Rudy Umans – https://rudy-umans.pixels.com
January 22, 2023