Solargraphy

[glajciorz]

Hi.
I send you my photos made with pinhole cameras.
The cameras were simply 35mm film boxes loaded with black&white photographic paper.
Pinholes were 0,15 to 0,25mm in diameter.
No chemical processing was necessary, just scanning, inverting colours and adjusting contrast.
The paper has been exposed from 24.12.2008 to 23.06.2009.






greetings
Adam

[Colin Kaminski]

Very Nice Adam!

If you are interested I would love to see you post those photos here:

http://www.cloudynights.com/ubbthreads/ ... ll/fpart/1

[glajciorz]

I saw the post on cloudynights.com - thanks
I belive the image is distorted (hence the bell-shaped sun tracks) since the paper was curled during the exposure.
You know what bothers me - why is the resulting image colour if I used black&white photo paper ?
Jeff, maybe you could help ?

greetings
Adam

[dave battin]

very cool Adam ! nice job ..............

[Colin Kaminski]

Hi Adam,

I had a few questions. Why do you think the solar path near your horizon flattens out (becomes bell shaped)? Some of the solar paths are closer than others, are the gaps from clouds or did you close a shutter?

[Tom B.]

Very pretty! Interesting that the photo paper became dark (on the sun trails) from exposure without chemical developing. I expect that impurities in the paper or atmosphere act as developers over time. I'll have to try some sun prints on some old paper stock and see. I too would love to know what caused the colors - maybe mold preferred not to grow on the areas with more light (or more metallic silver)? Or different lichen populations?

[glajciorz]

Why do you think the solar path near your horizon flattens out (becomes bell shaped)?

I was wondering how would the solar paths look like if the photo was made with a conventional camera.

Some of the solar paths are closer than others, are the gaps from clouds or did you close a shutter?

There were completely clouded days.

Interesting that the photo paper became dark (on the sun trails) from exposure without chemical developing. I expect that impurities in the paper or atmosphere act as developers over time.

What about photolysis Tom ?

I too would love to know what caused the colors - maybe mold preferred not to grow on the areas with more light (or more metallic silver)?

greetings
Adam

[Tom B.]

What about photolysis Tom ?

Yes, I think that's how it gets started, then maybe humidity and air pollutants help the metallic silver particles grow (develop) and also darken the silver. I have an old print behind glass that's gone quite metallic in areas - I expect that if it was directly exposed to air the metallic spots would darken from sulfur compounds etc. One experimental test would be to seal the can well, with a window behind the pinhole to prevent air exchange. It would be no fun though to have to wait a year to see the expected blank paper

Re color differences, maybe the different exposures cause different average particle sizes which scatter light preferentially at different wavelengths? Small particles -> blueish, big -> reddish

[Hans]

Very nice!

Are the colours related to the actual colours of the image or are they related to the intensity of the exposure?

[Tom B.]

Here's results from a experiment today. I mounted a 2.5 inch square piece of Ilford Multigrade IV B&W print paper in a homemade camera with Pentax 50mm f/2 lens, no UV filter, and exposed for 2 hours. First pic is a scan of the undeveloped image, fairly low contrast, but easy to see. Second pic is a rescan with adjusted black & white levels. Third pic is after removing the bluish cast and inverting to get negative image. I think the color depends on exposure level.

[glajciorz]

It seems that longening the exposure shifts colours towards blue. There were no blues on my 3-months exposure, but with 6 months there were.
Tom, would you try recording sun paths with your camera ? During let's say 1-2 days (for the beginning ) ?
Another idea - why not load the camera with low-sensitivity material (for example holographic plate) ? What I mean - with a pinhole camera the aperture is extremally small, so one uses relatively high-sensitivity material (photo paper). With a camera with f/2 lens a less sensitive material should work.
Or maybe a combination of Polaroid material, classical camera and long exposure would give interesting results.

greetings
Adam

[Tom B.]

With a test strip of the Ilford paper in direct sunlight, it eventually darkens to a light neutral grey after about 1/2 hour and then stops (self limiting). I might try some more things this weekend - weather permitting. I have some old unexposed PFG-01 film (a dud batch) that I can try, too.