February 10, 2011

Zero Image 25B

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The Zero Image 25b is a pinhole camera designed and built by Zurnike Au, in Hong Kong. It is entirely made in wood and brass and uses large format film: 4x5" (10x12cm).

Pinhole cameras, which use a small hole instead of the lens, have a very extended depth of field, from a few inches to infinite. On the other hand, they are less sharp then a traditional camera and show a significant vignetting.

The Zero Image 25B has a focal length of 25mm, very short compared with other pinhole cameras. It is equivalent to an 8mm on a 35mm SLR. However, unlike ultra-wide lenses and fish-eyes, pinhole camera do not produce any distortion of field: straight lines are rendered straight.

Having no lens, there is no focus or aperture to adjust. The aperture is fixed on f/138. The only thing you can set is the exposure time which can last several seconds (in a typical sunny day) or several minutes (in the shadow), with a 100 ISO film and considering the reciprocity defect.

Useless to say, a tripod is indispensable. There is not a real shutter, just a wooden lever that must be turned at the beginning of the exposure and put back in place after the required exposure time. It is very important to rotate this lever to its end position, otherwise there may be the risk to cause some serious vignetting in a corner.

The Zero Image 25B has no viewfinder, so it is not very easy to position the camera in order to aim the subject (a bubble level can be of some help). The most common mistake is to be not enough close to the subject. Considering the very wide angle, it may happen that the shadow of the tripod is included in the final picture, or even the tripod itself.

Using large format film requires familiarizing with film holders, learning to identify the emulsion side in the dark when loading the film, removing the dark-slide before the exposure and putting it back (following the convention: white side out = unexposed film, dark side out = exposed film or no film in the holder), developing the film. I use a tray, in total darkness, with a phosphorescent darkroom clock (a valid alternative can be a recorded audio track with alerts every half a minute).

The wide taking angle and the vignetting very often end up in a very extended tonal range of the scene. This can be a serious issue and shall be managed by reducing the contrast of the film. The reciprocity defect also contributes to increasing the contrast. I usually expose the film at a lower ISO (-2/3 stop) and reduce the developing time by a 30%. Maybe one day I'll make some more thorough tests.

The Zero Image costs about a hundred dollars, directly from Hong Kong (but there are importation taxes to pay), or about a hundred pounds in UK (e.g. from Silverprint).
Not very much for a tool that offers many creative possibilities.

Here you can view a few images I took with this camera.

A few references:
  • the Zero Image official site 
  • the web site of Scott Speck, a master of the Zero Image
  • Pinhole Photography, a book by Eric Renner

1 comment:

  1. Thanks a lot for the article! It was very informative and helpful.