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The Un-Round & Multi-hole

The Un-Round & Multi-hole

UNROUND

We can be MUCH more "playful" than scientists. Imagination and willingness to try new things are essential here.

Some general rules:

• round is the "sharpest" possible pinhole under normal conditions
• any deviation from round will affect the sharpness and the "feel" of the image.
  example: an oval or short slit will smear the image in the direction of the longest dimension of the hole.
• points of light in the image will take on the shape of the pinhole.
  examples: a ring shaped hole will produce ring shaped halos in parts of the image. A star shaped hole will produce star shaped halos.

MULTI - HOLE

Rules:

• each pinhole will cast its own image onto the film plane
• the range or width of the image produced is determined by
  • the angle from the perpendicular
    this may not be obvious. Looked at head-on, a perfect pinhole looks round, but as you get further and further away from head-on, the hole looks more and more oval until it disappears. The thicker the material the faster this will occur, but even an infinitely thin material disappears at 90° (edge on). And the smaller the hole, the less light gets through and the lighter will be the image on the film plane. Note the 'hole' is also no longer round. As per above explanation of the unround hole, the image becomes distorted. This effect is most pronounced in extreme wide angle images.
    
  • the chamber shape designed into the camera

So in practical terms this means there is a "fall off" in the image away from the center.

• the closer pinholes are to each other the more likely there will be overlap in the images unless there is something structural to prevent this from happening. Pinholes are VERY wide angle. So, even on a 4x5 with a 33mm focal length pinhole, almost the entire frame will be covered.

This gives us two possibilities:

• overlapping images, or double exposures from different angles to the subject
• side by side images with different angles to the subject

From this we can add intentionally, a third possibility. Time. One pinhole need not be used at the same time as another, hmm……

(the separated pinholes would produce a stereo pair, hmm, 3D pinhole)

Part of the magic of pinhole is the infinite number of possibilities, but don’t forget the aesthetic side! Good subjects and composition are still the best images. We should not depend on "special effects".

BugCam

This is an example of the extreme in multihole cameras. 32 ideal pinholes of about 12mm focal length onto 4x5 film.