Introduction: Cyanotype Camera Obscura
Cyanotypes are prints made with light striking ferric ammonium citrate - potassium ferricyanide empregnated paper. The ferric ammonium citrate is the light sensitive compound. The prints are negatives, dark things are white and others are various shades of blue. The technique dates to 1842 with Sir John Herschel using it to make inexpensive copies of astronomical calculations. In 1843, Ms Anna Adkins made booklets of British Algae and hers is recognized as the first picture book in history.
The literature, “Cyanotype” from Sarah Van Keuren’s book “A Non-Silver Manual: Cyanotype, Vandyke Brown, Palladium & Gum Bichromate with instructions for making light-resists including pinhole photography”, was used for the exposures and basic camera design. The prints were developed and rinsed with water as the manufacturer of the Sunprint paper instructed.
Most of the materials needed are in Photo 1. The shoebox, duct tape, wood glue and cardboard are for fitting the lens into the box. The paint is matte Black. The Solar Print paper was for $7:00 at a local toy store. Not shown, but used, were cheap wooden chop sticks used for furring strips and shimming - Popsicle sticks could also be used.
The lens is an old, school projector lens I got for free as our old school converted to digital projection. The lens has written on it: "Ektanar C 102 - 152 mm f 3.5 zoom projection". The focal point was 5.5 cm from the rear of the lens and could be varied by twisting the zoom.
Step 1: Box Made
First, all of the holes in the shoe box had to be covered. Then the lens hole was cut out and.the lens fitted and seated using cardboard strips. Glue was placed in the cardboard "bed".
5.5 cm from the rear of the lens a cardboard wall was placed and held with glue and furring strips as seen in the photos.
Step 2: Sunprint Paper Holder
In this photo you may see the wooden strips making a Sunprint Paper holder. The print paper will be held by these strips while the exposure is taking place. The paper is free between these holders. I think this may have added to undulated focus in the prints. This will be better done in version 2.0 of the cyanotype camera in that perhaps I will use a plastic sheath for the print paper to hold it on more securely.
Step 3: The Completed Cyanocamera With Address Label
With the lens bed and the focal point securely glued into place, flat black matte paint was sprayed both inside and outside.
The lens was fitted into the box, light leakage was checked and covered. With exposures of 40 minutes or so, I placed an address label on the box so I could take it somewhere and leave it for an exposure. Even out here where I live, people may see a box and think it is some sort of explosive device. I hoped that the address label would make someone telephone me before calling in the Sheriff.
Step 4: Fields and Trees(1) and Dirt Road (2)
The cyanocamera was loaded with Sunprint paper and exposed for 40 minutes to a field scene for (1) on an overcast day. Development was with rinsing water according to the manufacturer's procedure. The round, upper right object was a heavy flashlight I used to weigh down the lid of the box because of construction that might jar it.
The dirt road(2) was exposed for 45 minutes, but with more Sun and no flashlight. I was curious because of the deep blue road which appears black in the cell phone picture.
The literature indicated that the blue paper would turn mostly white during the exposure. I noticed that there was lot of blue left on the sunprint paper after the exposure.
Step 5: Positive Prints
The developed Cyanoprint was photographed with a cell phone for permanency as the blue and white began to mull rather quickly. Within about 45 minutes after the rinsing, the mulling was so great that significant detail was lost.
Shown is a positive print of the blue Sunprint Negative using Smart Photo Editor for the conversion.
This i'ble was a lot of fun! Very special for photographers and artists interested in alternative processes!