Stone Knives And Bear Skins – Part 1

Danger – long post ahead!

I have been looking at my website during these cold days and reconsidering its contents. In doing so, I came across an article I wrote over 15 years ago (pre-digital), and realized how it applies even more today. A few months back I came across someone who remembered reading the article and was all over the place about being glad to meet me because it had had an impact on him and his work. One cannot buy the feeling that accompanies this experience.

So I’ve decided to offer the article in two parts. Sometimes it’s a good idea to go all the way back to the beginning.

Click for larger image

Click for larger image

As the proliferation of technology continues to force its way into our lives, the hobby of producing images through photographic means has followed suit. Every aspect, from the exposure of film, through print production, has offered the photographer the ability to lose control of the art form. Whereas this may increase production, one wonders who should actually be allowed to sign the final product.

As a means of reversing this tendency in my own work, I decided to take complete control of as many aspects as I felt technically feasible. This sent me in two directions: expose the negative, not with an expensive automatic-everything camera, but with a pinhole camera, and create the print, not with commercially-produced paper, but coat my own and print using the sun. Stone knives and bear skins.

This article is the first of two parts where I will suggest that looking backward, when everyone else is looking forward, may be a consideration not only for contrarians, but also for those who wish to separate themselves from the field. Do I suggest tossing our cameras and paper away to follow this path? I would no more do so than suggest one remain using a single film, paper, and set of chemicals. This is a direction, a means of extending oneself, a way of improving other aspects of one’s photography by seeking another posture.

Part I – Stone Knives

Pinhole takes us to the very essence of photography. At this level, depth of field no longer has meaning, captured light strikes the film plane without the intervention of any modifying factors, and the creation of the tool can be done entirely with materials one already owns. Doing this, we are separated from the mainstream and have the capability to create unique images. Is this not what artists aspire to obtain?

Pinhole photography returns us, perhaps, to the very beginning of photography (it is possible that the first photograph by Niépce in 1826, an eight hour exposure, was a pinhole image). Of course, this idea has been around considerably longer. Ibn al-Haitham (965-1039 AD) wrote of the use of the pinhole to study light rays, Theodoric of Freiberg and Kamal al-Din al-Farisi (14th century) independently used the pinhole to explain the rainbow’s color principals, and some Italian cathedrals in the 15th century contained a pinhole in the ceiling to tell the time. The first use of the camera obscura (a term coined by the astronomer Johannes Kepler) was used by Gemma Frisius to study the solar eclipse of 1544.

The basics of pinhole photography is very simple. Light enters a light-tight box through a very small, lensless aperture, striking the film. If this was the only principle involved, could increase the sharpness of the resultant image by reducing the size of the aperture. However, another element, diffraction, comes into play. This was first demonstrated by the Italian physicist, Francesco Grimaldi, in 1665, where light passing through two consecutive pinholes displayed wider than it should have. The smaller hole, therefore, will increase diffraction, working against the image’s sharpness. The photographer working to obtain the sharpest possible image needs to find a balance between these two conditions.

In addition to this diffraction, it was noted that the boundaries showed coloration. The wave theory indicates that the wavelength is a determining factor of the resulting diffraction — the longer the wavelength, the greater the diffraction. As the red end of the visible spectrum has a greater wavelength than the purple, it is diffracted more, and will show on the outer boundaries.

The nuts and bolts of pinhole photography can be as extravagant, or plain, as complex or simple, as imaginative or straightforward as one may wish. A good starting point is to determine how to make the hole and how large it should be. The instructions I will give have yielded for me quality round pinholes that yield a surprising sharpness. Certainly, if one wishes to work for a less sharp image, simply deviate from the suggested size or roundness of the hole.

There is no consensus as to exactly which proposed formula will actually yield the aperture value for optimum pinhole size. I have relied on the following formula primarily because of its simplicity.

A = square root of 55 * F, where A is the aperture in thousandths of an inch and F is the focal length in inches.

For instance, if your focal length is 10″, the square root of 10 * 55 is 23.45 thousandths of an inch. It is best to convert this to millimeters, as I will explain, so our final value is 0.02345 * 25.4, or .59mm.

The material for creating the pinhole can be anything thin and easy to work with, and I have found aluminum pie pans to work nicely. Cut 1″ X 1.5″ strip and tape it onto a surface. Break a sewing needle in half and shove the blunt end into a pencil eraser. Place the sharp end of the pin in the middle of the aluminum and gently rotate the pencil, barely exerting pressure. Soon, you can remove the needle and find that a hole has been formed. Remove the tape, turn the aluminum over, and use very fine sandpaper to very gently sand the back side of the hole in a circular manner. Place the aluminum in a glassless slide mount. This makes the pinhole a bit more resistant to damage, as well as giving you a place to put notes, like the size of the hole. Voila — a pinhole.

Determining the size of the pinhole is no problem. Raise the negative carrier of your enlarger and focus to the point where 1″ in the carrier will be displayed as 10″ on the board (note: your 35mm carrier may not be 1″ wide, so carefully measure before determining that you have set the proper height). Place the slide in the negative carrier and turn on the enlarger lamp. The projected light will display the hole ten times larger. Place a ruler with a metric scale underneath and examine with a magnifying glass to determine the size of the hole.

I would suggest creating several pinholes and writing their sizes on the slide mount. You can then construct your camera to the focal length of the pinhole. Of course, if the hole is smaller than you would like, you can repeat the series to create a larger pinhole.

Projecting the hole also allows you to closely examine the quality of the hole. Anything other than a clean circular hole will cause additional diffraction.

When you are satisfied with the hole, place a very small piece of tape over the hole while you spray paint it flat matte black. The box you use should also have been spray painted flat matte black.

Determining exposure is only tricky because we are accustomed to using apertures like f8 and f22. In the above example, the f-stop would be 10″ / 0.02345″ or f426. Certainly, you will need to understand the reciprocity of the film you will be using when determining the exposure time. As this could well be into the minutes, as opposed to small portions of a second, an accurate shutter will not be necessary.

So there is your stone knife, to use or abuse it as you wish. tomorrow I will suggest the bear skin, the Van Dyke process, for printing the negatives.


About GLSmyth
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