Solargraphy

glajciorz · Post by **glajciorz** » Fri Jul 03, 2009 7:55 am

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 · Post by **Colin Kaminski** » Fri Jul 03, 2009 3:34 pm

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 · Post by **glajciorz** » Fri Jul 03, 2009 7:51 pm

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 · Post by **dave battin** » Fri Jul 03, 2009 9:25 pm

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

Colin Kaminski · Post by **Colin Kaminski** » Sat Jul 04, 2009 3:11 am

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. · Post by **Tom B.** » Sat Jul 04, 2009 7:53 am

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 · Post by **glajciorz** » Sat Jul 04, 2009 10:36 am

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)?

:think:

greetings
Adam

Tom B. · Post by **Tom B.** » Sat Jul 04, 2009 9:29 pm

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 · Post by **Hans** » Sun Jul 05, 2009 8:13 pm

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. · Post by **Tom B.** » Mon Jul 06, 2009 12:55 am

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.