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| Abe Morelle makes images by photographing the camera obscura effect in rooms. This image is projected on the wall by means of a pinhole. |
Box
black gaff tape
tinfoil
sewing needle
sandpaper
black matt paint
essentially, pinhole is dead easy.
Make a box light tight and the interior black.
Make a hole where you want to put you're aperture.
Get a piece of tinfoil and a
sewing needle. (sewing needles come in different gauges and as such you may select your idea aperture, the smaller pinhole and thinner surface, the sharper, and the longer the exposure). Vignetting occurs as the diameter of the hole approaches the thickness of the material in which it is punched, because the sides of the hole obstruct the light entering at anything other than 90 degrees.
sewing needle. (sewing needles come in different gauges and as such you may select your idea aperture, the smaller pinhole and thinner surface, the sharper, and the longer the exposure). Vignetting occurs as the diameter of the hole approaches the thickness of the material in which it is punched, because the sides of the hole obstruct the light entering at anything other than 90 degrees.
Poke a hole in the tin foil with the needle. Very Gently.
Tape the tinfoil over the opening in the box making sure it is completely secured with no light leaks.
Take a piece of the gaff tape and make a tab which will cover the aperture when not exposing, working like a shutter. The film or photo paper will go in a holder or directly inside the box adjacent to the aperture.
The math and science:
where d is pinhole diameter, f is focal length (distance from pinhole to image plane) and λ is the wavelength of light.
The f-number of the camera may be calculated by dividing the distance from the pinhole to the imaging plane (the focal length) by the diameter of the pinhole. For example, a camera with a 0.02 inch (0.5 mm) diameter pinhole, and a 2 inch (50 mm) focal length would have an f-number of 2/0.02 (50/0.5), or 100 (f/100 in conventional notation).
Due to the large f-number of a pinhole camera, exposures will often encounter reciprocity failure. Once exposure time has exceeded about 1 second for film or 30 seconds for paper, one must compensate for the breakdown in linear response of the film/paper to intensity of illumination by using longer exposures.
exposure times
we were using photographic printer paper in our pinholes.
Photographic paper has an ISO or film speed of somewhere between 4 and 10. A good way to think about this is in comparison to average film speed which is 200 or 400. Exposure times for those average films on a sunny day or fractions of seconds, whereas when we made our exposures onto photo paper it took much longer. The shortest exposures being 45 seconds to 4 min. depending on how much sun/shade and different camera shapes. The light will change, especially in Edinburgh. But, it is really important to make notations of the lighting conditions, time of day, date and exposure time. This way we can make several tests before making a full exposure.
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| Edinburgh pinhole artist Katie Cooke http://slowlight.net |
some good links:
Next week we will be doing paper negatives and Cyannotype!
You should bring:
Images- please make photocopies/ prints on transparency of pictures you would like to print from
these should be in negative form and black and white- if you have black and white negatives larger than 35mm (120 or bigger) this will also work very well- if you are unclear about this email me as soon as possible.
We will also make photograms- bring interesting objects to arrange artistically
ex: feathers, tools, light bulbs, toy dinosaurs, teeth, fruit pieces - be creative
if you can, please continue to do work with your pinhole camera- you can purchase photo paper at many stores around town- ECA school store, Camerabase on morningside and Jacobs on Shandwick Place, are reccomendations. I would like to show you how to make your negative exposures into positive prints.
Printmaking paper - hot press Arches, is a standard - you can buy this at ECA school store
Foam or Hake brushes - which ever you prefer- get 3 total
bone folder (optional) / awl - this is for tearing paper as well as book binding.
I think i would like you all to take a look at the BB (see here) and figure out which process you would like to sign up to make a page for our class book. I have links to examples of each process. I would like each person to make a page and have each process represented. We will need to make multipuls so that everyone in the class can have a book at the end. The sign up list is not set in stone- you will be allowed to trade if you find you really hate the process... but i'd like a temporary list on Sunday.
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