May i pick your brain about an advanced Solargraphy question?

[RockAndRolf]

Good day,
I'm on vacation for the next few weeks and I can finally finish a few projects. Normally I'm a big fan of the trail and error mentality, but unfortunately this experiment takes too long for that, so I'm asking you for insights that can solve possible problems. An idea I've had for a while and is now quite advanced, is a solargraphy camera that doesn't use a pinhole, but a "real" lens. So instead of a circular pinhole camera in a can I want to make a box camera with a ultra wide-angle lens and ND filters in order to achieve the correct exposure. I now have a lens, ND filters and a photographic medium in the right format.

The idea:
I have two Minolta 195mm F6.5 photocopier lenses that I can reduce to F45 with an internal waterhouse stop. These lenses fill a 30x40cm negative at >F22. On this I can place two 10-stop ND filters of 58mm on the back of the lens (to prevent reflections and possible water damage). I've confirmed that they only minimally vignette by just inserting the housing of the filters, this only minimally reduces the image circle. I was able to get the two actual filters in one housing, this saves an extra ring, and therefore vignetting. It's impossible to test what this does for the image quality in a short time because no visible light comes through a 20 stop ND filter, but let's hope for the best. Because I don't want to leave a real camera outside for half a year, I'm going to build a box camera and paint it a few extra times. The lens has no openings on the shaft and only allows moisture to enter through the filter thread that the glass is attached to. That way I can put some silicone sealant over this to prevent moisture problems. I can also load RC paper into the darkroom once, so there are no problematic openings in the housing. And just to be sure, I can stick Silica bags in the part where no light passes (against the front panel), I already have these.

Possible problems:
Reciprocity:
The longest exposures I've done on Illford MGRC are around 2 hours and I had no visible problem with reciprocity. Well, this is a completely different order of magnitude in exposure time.
Using two 10 Stops filters. I have no idea if something like this is still useful, although apparently there is a 24-stop filter that works with digital cameras. Fortunately, I'm not too afraid of the color shift, because I use black and white paper.

Vibrations:
To prevent this, I'm going to anchor one camera to the corner of my brick shed at home, and the other to four sturdy posts at a friend's estate.

Exposure:
I calculated the exposure based on 13EV on average for 12 hours of light per day (in the Netherlands). This gives me 20 stops ND at F45 for 192 full days of 24 hours, so just over half a year. But from experience I have noticed that a stop more or less is not an immediate problem with this paper, so I do have the necessary leeway.
Do you see any problems that I didn't foresee? or do you know of anyone who has tried something like this before? I can't find anything except the regular solargraphy cameras.

Thanks for reading, and if you have anything to add please let me know, otherwise hopefully you'll see the results here shortly after the longest day of the year. I try to keep you informed.

[jnantz]

hi
sounds like a fun experiment! I really can't help you with exposures or anything like that. have you looked on alternative photography . com for information? or looking at the work of chris mccaw to give you insights? when I started making retina prints ( long exposed prints on photo paper that can't really be processed or fixed because they are ephemeral )I was exposing for IDK 1-12 hours, I now get 6 minute exposures with a f10 lens. Its not a solargraph camera but just a camera, not pointed at the sun to trace it's path but at construction sites, landscapes, seascapes &c, 11am mid day sun or 4pm late afternoon sun.
I'd be more worried about your lens or camera getting damaged by the elements. have you tried this with welding goggles instead of the 10 stop filters? I know people use those, but unfortunately it cuts some of the UV which is needed along with blue light to make the image.

[nolindan]

Reciprocity failure is a function of light intensity. For film, the exposure time is used as a stand-in for the intensity of the light falling on the film. Slow film has very little reciprocity failure - but that is because the light intensity required to form an image is higher. Ditto photographic paper, which has an ISO speed ~3.

In an exposure that will capture the traverse of the sun the light intensity on the paper will be quite high. 20 stops of ND filter is about a 1:1,000,000 attenuation - I have no idea if that is too much, but a short one hour exposure should tell you. The exposure for the scene's foreground may be another matter. At ISO 3 sunny-16 yields a 1/3 of a second exposure. There 32,000,000 1/3 second exposures in a year and so a 1,000,000x attenuation means the foreground will be overexposed by 5 stops, don't know if this enough to get over reciprocity failure.

Actually, you only need 1/2 a year's exposure - solstice to solstice.

[jnantz]

Ditto photographic paper, which has an ISO speed ~3.

paper doesn't have a relative ISO of 3 its about 24 in sunlight. it's a sliding ISO because of varying intensity of blue light...

[RockAndRolf]

Thanks for the responses.

I looked at Chris McCaw's work years ago, the links from the search engine were still purple . Although the goal is somewhat similar, the technique is very different.

ISO 3 may be a bit on the low side, but for most exposures I shoot on this paper I use around ISO 3 to 5. That gives pretty good results at 3 minutes in about 20 degrees celcius 1+100 rodinal. This is measured to illuminate the environment normally, not so much the sun itself, which is allowed to saturate.

I am indeed still planning to take some kind of test photo to test the camera and focus. But for that I need 6 average days with F11 and two stops of underexposure. Now the winters here are pretty dark and they barely reach 6-8EV on average, so I don't think I have that time.

Now that I think about it, 13EV on average might be a bit too high since there are also a lot of days like this until March/April. So one or two stops faster may well work out better, also because overexposure is easier to correct than underexposure. And if Reciprocity does occur, I also corrected it a bit.

And if it doesn't seem to work after half a year, it was at least a fun experiment and I'm sure I learned something so that the next half year yields a better result.

[jnantz]

Thanks for the responses.

I looked at Chris McCaw's work years ago, the links from the search engine were still purple . Although the goal is somewhat similar, the technique is very different.

ISO 3 may be a bit on the low side, but for most exposures I shoot on this paper I use around ISO 3 to 5. That gives pretty good results at 3 minutes in about 20 degrees celcius 1+100 rodinal. This is measured to illuminate the environment normally, not so much the sun itself, which is allowed to saturate.

that's fantastic you are able to expose them like a normal print and develop them out, most people who do this sort of image making have troubles with black prints ( developing even in weak developer ) or white prints ( fixing even in weak fixer) and grey prints ( after time spent in a dark place for 4 months ).

hope you post a link to your images when you complete your project sounds like a lot of fun.

[nolindan]

If you are using a printing out technique, with no development, then the image tones can be (mostly) preserved with S-30 stabilizer. See https://www.photrio.com/forum/media/...n-print.33407/ for an example.

[jnantz]

not sure that will work with things that are chemical stains (I've never tried it!) ... IDK I think the difference between a lumen print and a long exposed print is when a lumen print is exposed in the sun,
the organic matter from the plants sweat and the phenols (?) &c sweat out of the plants and mix with the photo emulsion and develop it out, long exposure is something like a visible latent image that's stained
on the surface of the print. even had Ron Mowrey stumped ( or so it seemed )
what does work is either baking or washing soda it somehow / sometimes stabilizes the image enough to be developed and fixed. if it's being developed in caffenol (figure that out my mistake )
( after the washing /baking soda bath ) even better, it's also full of washing soda / baking soda, and allows for the image to be kind of / sort of fixed . I don't know for sure, I have never used color chemistry...

[johnasavoia]

I have made many solargraphs in lensed cameras and found solarization/sabatier effect is an issue I had not heard mentioned before. Underexposure is just as common though. I had done a series of 2wk exposures @f64 (no ND) over several months with varying weather and found it to be a solid exposure, I wanted to do a very long exposure using an ND16, so I did a test at f8, same 2wks, and found it underexposed. I ended up attempting 4 months at f32 & ND16, the result was very disappointing, far far underexposed even though it had been the sunny summer months. Perhaps it was my inexpensive ND, perhaps the ND cuts some certain band of light that the paper absorbs more than traditional methods of photography would have me think.

I haven't tried this yet but I am more eager to attempt a pinhole aperture/waterhouse stop in lieu of the ND filter as pinhole exposures are a more known quantity, but add in the glass elements for a more optimal field of view & composition.

Many of my solargraph experiments, both lensed and pinhole, can be seen on Flickr; https://www.flickr.com/photos/johnas...57719143760552

[Tin Can]

Just looked at your entire flickr

Very impressed!

your comment no chemistry used

Do you mean ALL?

Perhaps post come to a YouTube I follow, she thinks aliens are everywhere

IDK

I have made many solargraphs in lensed cameras and found solarization/sabatier effect is an issue I had not heard mentioned before. Underexposure is just as common though. I had done a series of 2wk exposures @f64 (no ND) over several months with varying weather and found it to be a solid exposure, I wanted to do a very long exposure using an ND16, so I did a test at f8, same 2wks, and found it underexposed. I ended up attempting 4 months at f32 & ND16, the result was very disappointing, far far underexposed even though it had been the sunny summer months. Perhaps it was my inexpensive ND, perhaps the ND cuts some certain band of light that the paper absorbs more than traditional methods of photography would have me think.

I haven't tried this yet but I am more eager to attempt a pinhole aperture/waterhouse stop in lieu of the ND filter as pinhole exposures are a more known quantity, but add in the glass elements for a more optimal field of view & composition.

Many of my solargraph experiments, both lensed and pinhole, can be seen on Flickr; https://www.flickr.com/photos/johnas...57719143760552