Solargraphy - Intriguing first time

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yesica-s

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Hello, this is one of my first solargraphs.
I've just discovered the tecnique and am fascinated.

I wonder...
Does anyone know why some lines appear darker than the sky?
Or why does that one line look so much brighter than the rest?
I noticed it happens in other solargraphs from other people as well.

I read about how cloudy days affect the result, but why the change in brightness/luminosity?

Thank you.


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Daniela

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Hi and welcome! (or should I say bienvenida? La Plata, Argentina?)

I think those darker lines are indeed still the sun, but dimmer. Do you notice how the lower lines follow the trajectory and go behind the building? Whether they are dimmer because the days were cloudy is a good guess.

I'd love to hear about the process. How long was the exposure? How did you make the camera?
 

koraks

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think those darker lines are indeed still the sun, but dimmer.

But Daniela, in a positive image, where light tones represent higher luminosities and dark ones represent low luminosities, how would the brightest element in the scene render darker than its surroundings?
The first thing I'm reminded of is actual solarization (not to be confused with Sabattier processing), i.e. reversal of tones due to extreme overexposure. If this is what's happening here, it would mean the darker lines are actually the sun on clear days, and the brighter lines are the sun on more hazy days, with cloudy days not leaving a line at all...

And indeed, welcome to Photrio, @yesica-s ! Would you mind telling us a bit more on how you made this image?
 

Ajven

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Wow,
I tried solargraphy this summer but my results are nowhere near yours. I slightly underestimated the fixation and pointing for almost two monthf exposure. I was worried about mold because it rained quite a bit during part of the exposure, but the paper in the tin remained dry after all. The bottom line shows that I finished exposition before noon :smile:

So, congrats to your results and welcome to photrio!


solar.jpeg
 
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yesica-s

yesica-s

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Hola! (yes, my native language is Spanish). Indeed, I am from La Plata, Buenos Aires, Argentina. Thanks for the warm welcome.
The camera was made with 2 beer cans. The pinhole (approximately 0,35mm diameter) done in a sheet of aluminum foil placed over a small aperture into the side of the can, at half height.
I used glossy Kentmere paper, and painted the inside of the cans with matte black spray. Also used duct tape to seal the camera once it was all done.

The camera was put on a terrace, facing East.
From 4th October to 17th October 2023: 13 days.


Here's the weather:

17 October - Sunny
16 October - Partly cloudy / Overcast
15 October - Sunny
14 October - Sunny
13 October - Sunny / Partly cloudy
12 October - Sunny
11 October - Sunny / Partly cloudy
10 October - Sunny / Partly cloudy
9 October - Sunny
8 October - Sunny
7 October - Sunny
6 October - Sunny / Partly cloudy
5 October - Sunny
4 October (Put on location at 17hs. I think you can't see this day) - Sun and Rain


And here are the raw files, prior to editing:

Negativo3.jpg
Sin edición2.jpg



It does sound like overexposure could be the reason for those dark lines, specially after taking a look at how the weather was like in those days. A lot of visible sun with no clouds.
I wonder what causes this potential overexposure. It may have something to do with the size of the pinhole? or the glossy paper?

I do like the result and will experiment more. More cans on the way.
 

koraks

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Ahh, but the additional scans make it a bit more clear. This is not an instance of tone reversal / solarization. What you're seeing is different hues because when printed out (as opposed to developing it), a silver halide emulsion creates different hues/colors depending on the degree of exposure.

If you take your scanned original, invert it and then only look at the red channel, you get a more sensible output:
1697725336138.png


By 'sensible', I mean something that intuitively feels 'correct' - not that it's necessarily more artistically appealing etc.
 
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yesica-s

yesica-s

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Ahh, but the additional scans make it a bit more clear. This is not an instance of tone reversal / solarization. What you're seeing is different hues because when printed out (as opposed to developing it), a silver halide emulsion creates different hues/colors depending on the degree of exposure.

If you take your scanned original, invert it and then only look at the red channel, you get a more sensible output:
View attachment 351396

By 'sensible', I mean something that intuitively feels 'correct' - not that it's necessarily more artistically appealing etc.

Thank you. That looks more accurate, yes.
Clearly editing is an important step in discovering what the can registered.

So having discovered that the red channel contained the most "accurate" representation of the sun (just because it always looks brighter than the sky), I'm still curious about why that one line looks incredibly brighter than the others.

I guess a lot of the reaction of the silver halide emulsion is actually random? but some of the fenomenons must have all sort of explanations. Do you know of a list of texts on where to study these processes? I've been reading some articles on the internet, but any recommendations are welcome.
 

Daniela

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But Daniela, in a positive image, where light tones represent higher luminosities and dark ones represent low luminosities, how would the brightest element in the scene render darker than its surroundings?

You're right...I didn't even think of the negative...🤦‍♀️

Hola! (yes, my native language is Spanish). Indeed, I am from La Plata, Buenos Aires, Argentina. Thanks for the warm welcome.
De nada. Yo Cordobesa de nacimiento, Santafesina por adopción, Parisina porque me trajo el viento :D
 

koraks

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I'm still curious about why that one line looks incredibly brighter than the others.

It's probably not just one line, but a few lines overlapping each other. They may be brighter due to pinhole geometry (a punched hole will collimate light to a small extent), beer can positioning, weather conditions etc.

I guess a lot of the reaction of the silver halide emulsion is actually random?

No, I wouldn't call it random. It's actually pretty predictable and consistent. Otherwise, it would be impossible to manufacture film and paper with any consistency.

Do you know of a list of texts on where to study these processes?

Which processes exactly? There's thousands of books, articles, websites etc. on silver halide technology spanning the late 19th century to present. The number of publications is so massive because it's a very broad field; the chemistry and physics of silver halide emulsions is very diverse, as well as very deep. I'd start by formulating some specific questions about what you'd like to know and then using those to perform some simple Google searches. Most of the basics are covered in freely accessible texts and sometimes even YouTube videos.
 
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yesica-s

yesica-s

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De nada. Yo Cordobesa de nacimiento, Santafesina por adopción, Parisina porque me trajo el viento :D

:smile: Saludos por allá!


It's probably not just one line, but a few lines overlapping each other. They may be brighter due to pinhole geometry (a punched hole will collimate light to a small extent), beer can positioning, weather conditions etc.
No, I wouldn't call it random. It's actually pretty predictable and consistent. Otherwise, it would be impossible to manufacture film and paper with any consistency.

Yes, what you described here is what I had in mind when I mentioned "random" results. Something you can understand to an extent because there's science behind every detail, but it may be difficult to determine exactly what caused each variation. Whether if it was the can that moved, or it had something to do with the geometry of the pinhole, etcetera.


Which processes exactly? There's thousands of books, articles, websites etc. on silver halide technology spanning the late 19th century to present.

What I had in mind here was researching about why the red channel contained the visibly brighter lines, and not the other channels, for example. I will continue searching the web and this forum as well for more information. Thank you for your help, it's very much appreciated.
 

koraks

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What I had in mind here was researching about why the red channel contained the visibly brighter lines, and not the other channels, for example.

Ah, okay. Well, my choice for the red channel was simply based on the overall look of the original image tending towards red, so it was kind of an obvious angle to take. Combine this with the notion that lumen prints tend towards hues that are close to the red part of the spectrum (i.e. yellows, tans, reds, purples) and red made sense to me.

The question then of course becomes why silver halide prints out in these red, yellow etc. hues. This is apparently due to (at least in part) grain size, with tiny silver grains being white to colorless, and they progress through yellow, orange, red and ultimately brown, black and violet/blue as they grow bigger. There are more aspects to silver grain hue, I suppose, but grain size seems to be an important factor, at least.

Although these sources are not the strongest ones, they do illustrate the point:
https://nanocomposix.com/pages/silver-nanoparticles-optical-properties (from a commercial firm apparently selling silver nanoparticles)
https://mse.engineering.ucdavis.edu...ine-files/GAANN-exp-6-Silver-Nanoparticle.pdf (instructions for a lab exercise; the illustration on page 1is useful )
 
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kykr

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Interesting points about how the color is introduced to black and white paper, I wondered how that happened. This is my latest attempt based on a 5x7 sheet of Ilford MGRC in a 16oz beer can. I spent all of about a minute editing it, just global corrections. It’s been unusually clear here for this time of year.
 

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Sirius Glass

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Welcome to Photrio. You are motivating me to find a suitable location to set up the equipment. Unfortunately my window are blocked by thick trees but if the trees were not there, I would have a great place to set up a solargraphy camera. Something new for me to work on. Thank you.
 

jay moussy

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I just did a raw scan of my first beer can solargraph, and will use tips found here to manage the color manipulation!
I left the device out a long time, did not take in consideration that the Sun would rise so much that the peak track is truncated.
Next time I should install camera with a slight angle.
EDIT: just added to gallery
 
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