Photographing without lens, the same (un)sharpness in all image areas and very long exposure times: This is what people associate with the term "build your own pinhole camera". The projects presented here go one step further. But above all, they are a lot of fun and encourage experimentation.
Razor blade aperture and multi-hole cameras
Building a pinhole camera yourself is also so popular because the time and materials required are kept within reasonable limits. Unlike a normal camera, pinhole cameras do not have an optical system of lenses that focus the light rays. Rather, the distance of the pinhole from the sensor determines the angle of view. The shorter the distance, the more wide-angled is the result. The smaller the pinhole, the sharper the shot.
One difficulty in constructing a pinhole lens is to make the hole as small as possible, but as accurate as possible, to avoid unnecessary blurring due to diffraction of light. Normally, a fine needle is used to pierce a hole in thin aluminum foil or cardboard. The result often has very frayed edges at the beginning, which can still be deburred with fine sandpaper. However, this requires some practice to achieve a good result.
An alternative is to buy a ready-made pinhole. It usually consists of a thin metal foil into which a hole has been lasered or drilled. This quality can’t be achieved with do-it-yourself tools. However, there are some alternatives, but they differ in the achievable image quality. But first I would like to deal with the different adaptation possibilities.
Pinhole camera mounts and camera connection
In the first step, the pinhole must be fixed in a mount. To do this, cut a round cardboard disc with a hole of about 12 mm in the center. The pinhole can now be attached to the back of this disc with transparent tape. The correct outer diameter depends on the camera adapter used. The pinhole can then be attached, along with the frame, to a camera adapter or modified camera cover with some double-stick tape.
Camera cover
The most cost-effective variant is to use a camera cover that is no longer needed. These are usually made of plastic and are usually already included with the digital camera. If you drill a hole with a diameter of about 10 to 12 mm in the center of the cover, the pinhole mount can be attached to the outside or inside of the camera cover.
M42 lens adapter and camera cap
Flat adapters to the M42 thread are available for almost every camera bayonet. To attach this to a digital camera, a modified camera cap is used, this time with an M42 thread. Since these camera covers are very inexpensive, they are well suited if you want to make several different pinhole variations. Due to the M42 thread, they can be changed quickly and easily.
Retroadapter
This also very flat adapter from the lens bayonet to a filter thread is actually used to adapt a lens in retro position to the camera. Here, the pinhole mount is simply inserted into the adapter and fixed with adhesive tape. Depending on the retroadapter used, the cardboard disc that serves as a mount for the pinhole may have to have a slightly different diameter.
C-mount adapter
With adapters to the C-mount thread, the lens thread is set back a few millimeters. This makes it possible to place the pinhole very close to the sensor. This way a very wide-angle result can be achieved. The mount of the pinhole aperture is simply glued into the adapter or, if it is a combined C-mount/M42 adapter, secured with a filter adapter with M42 male thread.
Zoom pinhole camera
Since with pinhole cameras the angle of view changes with the distance from the sensor, and not the focus as with a lens, a pinhole zoom lens is obtained with the use of one or more helicoid adapters.
Pinhole camera with razor blade apertures
For the first of the pinhole camera projects presented here, I would like to take a somewhat more unusual approach. Here the hole is not drilled, but assembled from several parts. This sounds a bit strange at first, but on closer inspection it is very similar to the way an aperture works in a normal lens. The base here is also a round disk made of black cardboard, which serves as a pinhole frame. Now cut commercially available razor blades into pieces about 20 to 25 mm long.
Three of these sections are glued to the cardboard disk with the help of tape so that they overlap each other and form an even hole. This works best if you work with a stand magnifier and mount the razor blades on a surface that is illuminated from below, such as a slide light table.
The edge sharpness of the hole also has an influence on the image quality. On the left a razor blade aperture, on the right a hole pierced with a fine needle in aluminum foil.
To align the razor blades exactly, use a lamp as backlight and a stand magnifier.
Pinhole camera with razor apertures
The procedure for the slit diaphragm is almost identical, except that here only two razor blades are used, which are mounted in parallel at a distance of about a quarter to a third of a millimeter, so that a very thin, evenly wide slit is created.
The results of the slit camera look a bit like images with motion blur or drag along, with the effect affecting the entire image. The length of the slit has an influence on the width of the blur. This can go from moderate to completely abstract. In addition, the direction of the blur can be influenced by rotating the slit lens.
The finished razor blade apertures in a cardboard frame. On the left a triangular pinhole, on the right a slit pinhole.
Build multiple pinhole camera yourself
The mounts have the same construction as the other pinhole cameras. The material used is a simple black cardboard, in which the holes are pierced with a thin needle. There are no limits to the number of holes and their arrangement. Here you can let off steam creatively.
Rows of holes, regular grids, ring-shaped arrangements and so on, everything is possible. If you do not want to use the center hole created by the cutting circle, you can simply close it with some black paint.
However, one must consider that the quality of the holes in a box is not very precise. But to try out a certain hole pattern, it is of course enough. Once you’ve decided on a pattern, you can then transfer it to another material, such as plastic or metal foil.
The necessary exposure times change with the size and number of holes, so that under certain circumstances times become possible that can also be realized without a tripod. The closer the holes are to the edge of the mount, the more likely vignetting becomes.
With a fine needle, countless variations of multi-hole inserts can be made.
When choosing a motif, you can follow the principle: "The more holes, the calmer the motif should be". In the case of strong color or formal contrasts, the original motif still remains recognizable, while small-scale, detailed motifs tend to have structures as the result.
Flexible pinhole camera made from Super 8 lens
Normally lenses of normal 8 or Super 8 cameras cannot be adapted to digital cameras. The flange focal distance is simply too small and the image circle would only illuminate a small part of the sensor format. Nevertheless some of these lenses can be used. However, to do this, all the lenses of the lens must first be removed. Only the aperture remains. Depending on the lens it can be closed very far. With the Westarit 1:2.5/12.5 mm used here, an aperture of about 0.6 mm remains at f/16, with the aperture fully open it is about 4 mm.
Since with pinhole cameras the sharpness of the image depends on the hole size, the modified lens gives you the opportunity to directly compare different hole sizes live.
The lens of a Super-8 camera without the original lenses becomes a variable pinhole camera.
The results range from recognizable to completely blurred. In addition, the lens can also be adapted to the camera with a helicoid. Then you get a zoomable pinhole camera with variable hole size. To what extent this can be used creatively, everyone has to decide for himself. However, it is interesting to note,
to get a very clear idea of the theory, if you change the parameters "hole size" and "distance to the sensor.
Pinhole camera images
Before taking the picture, the pinhole should be cleaned with a bellows to remove any dust that tends to settle unnoticed in the tiny hole.
As a rule, pinhole cameras should be used from a tripod because of the long exposure times involved. Depending on the hole size or number of holes, it is also possible to realize hand-held shots. Even shooting with flash is possible to some extent.
Especially the very long exposure times with small hole sizes have their very special charm. In addition to static motifs, flowing water, trees moved by the wind, or even busy city squares are among the motifs that lend themselves to pinhole camera images.
DIY in photography
This article is taken from the book "DIY in Photography" by Cyrill Harnischmacher.