Date: Mon, 27 Aug 1956 21:06:32 +0000
From: Ian Bleakney <bleekers@ousd.k12.ca.us>
To: pinhole@exploratorium.edu
Subject: Re: pinhole cameras
I do pinhole cameras every year in May (good sunlight) with my students.
I would urge any science teacher to give it a shot - it is probably the
most popular unit with my students. Creating a darkroom can be
challenging, but not impossible. My classroom has no windows, so it is
easy.
The last posting by Ellen Koivisto was an accurate description of the
basic how-to's. Here are some other useful things I have learned (or
stolen):
€ I believe that the pinhole itself is actually the most important thing
to get right (other than lightproofing the box). I cut a 1" x 1" hole
into the side of the camera and actually use a piece of aluminum soda
can (square - 1" x 1") taped over the hole. I use fine-tipped needles
to make a tiny (very tiny) "pinhole" in the center of the aluminum
square before attaching it to the camera. To do this: Place the
aluminum square on a table, press the needle point onto the metal and
rotate the metal square while pressing to get a even pinhole. Then be
sure to sand both sides of the square with ultra-fine grade sandpaper
and check to be sure that the pinhole is not clogged. Smaller pinholes
need longer exposures (up to 45 seconds on a sunny day) but make superb
negatives and positives)
€ Pinhole negative prints are fascinating, but it is also rather simple
to take the negatives from the pinhole camera and make "contact
positives". Have students just place a dry negative on top of an equal
size piece of unused photo paper in the darkroom. Then flash the white
lights on and off as quickly as you can in the room. Develop that piece
and you'll have a decent positive image.
€ Here is a big timesaver that helps out a lot. Have students do a
"test strip" trial to check lightproofing before they take photos.
Place a small square of photo paper into camera. Take out into sun for
1 minute - do not open shutter. Go back into darkroom and develop film.
Paper should come out white or there is some kind of light leak. Also a
good way to introduce darkroom chemical techniques.
€ Have studenst keep a log of each photo attempt: exposure, location,
light levels, time in developer, etc. Then have them adjust exposures
etc to get the perfect print.
As usual, it takes a few tries to get it right.
Ian Bleakney
Oakland