Thursday, June 20, 2024

Celebrating Stereoscopy Day: Stereo Solargraphy.

World Stereoscopy Day, organized by the Brian May Archive of Stereoscopy, occurs on June 21 (not the solstice - that was the day before in the Central Time Zone anyway). It commemorates when Sir Charles Wheatstone read his paper on Stereopsis to the Royal Society in 1838, seven months before Fox Talbot announced photography. 

Just before the Winter Solstice in 2022, for my second effort at a blog post for the celebration, I thought it would be a bit different for the upcoming 2023 Stereoscopy Day the next summer to mount a series of stereo pairs of solargraph cameras, where the long term bludgeoning of the sensitive emulsion and the path of sun drawn by our rotating, tilted planet, create an image without development. I had done a so-so attempt at stereo solargraphy before, but with a crucial error. I couldn't think of any interesting relatively protected places that I had access to and ended up doing a rockin' set of stereograms in the garden at the last minute.

As any solstice nears, the solargraph community chatter picks up and I was reminded of the stereo project last winter. Keeping moisture out of a camera mounted outside in the weather is a problem that you have to address. I had the emulsion completely dissolve off a sheet of paper once in a can just attached to the side of a building. It occured to me that cameras attached right up against windows wouldn't have that problem and simultaneously thought of several places, with the help of some collaborators, that would be pretty cool to mount a solargraph camera, not to mention a stereo pair.

This was less than a week before the solstice. I made eight pairs of cameras for the project. Two more came a week later and one existing camera also got enlisted. 

Here are the first eight, mounted the day before the solstice. The other three were later and are a little different. They're about as simple as you can get and still call it a camera. I dislike curved film backs, so they're for 6x6cm flat negatives, which also happens to be a classical format for stereograms, with the 90 degree, 30mm distance to the pinhole I use all the time. It's very handy that the standard issue graphic artist's steel rule is 30 millimeters wide so they could be layed out and cut pretty quickly. The slight extra width on the outside box was just eyeballed. The insides are lightproofed with self adhesive chalkboard black shelf liner. If you had been wondering why I had the sudden epiphany about the interior structure of a Populist, this was it.

I hand-drilled all the pinholes.

It's hard not to get braggadocious about this, but I drilled these eight matched pairs all in a row. They're mostly .25mm, plus one .22mm and one .28mm pair, so between f107 and f136. They're not perfectly optical diffraction (.23mm) but as good as any other of my pinholes from their appearance in the microscope.

I cut the last of the roll of brass shim stock from my 1991 grant into squares for this project (I still have a few left).

They're loaded with Grade 2 RC semimatte photographic paper left over from my 2016 workshop with teachers. Since my earlier attempt at stereo solargraphy was undone by a curved negative and there was no reason for them to be transparent, I mounted them on card stock and pressed them tightly into the camera back with a bit of doubled masking tape to make sure they stayed put.

Out of the eleven placements, it was surprising that both sides of the glass could be cleaned for all but two, and with those, it turned out most of the dirt was on the inside.

The majority of the places were with a fairly distant view (not even taking the sun into account). They are placed between 15cm and 30cm apart to extend the baseline, often limited by the depth and width of the window they were going against. This was what the post about the extended baseline cameras was all about.

I'm going to present these here for crossed eyes viewing, my favorite format, which requires no additional equipment. Crossing your eyes makes a double image. When the left and right images meet in the middle, you refocus on some element in the image and it snaps into depth. Because your eye muscles can adjust the overlap of the images, it's very forgiving of images that aren't perfectly matched and kind of tricks your brain into seeing depth even where the images don't overlap. It's also in full color, which if the images don't exactly color match is blended together by your brain. Here's a lesson with simplified graphics to learn how to do crosseyed viewing, which I've been told works. There are lots of other resources to learn to do it on the interwebs.  Parallel Holmes stereocards are available at this PDF if you want to print those or can do parallel viewing. Sorry anaglyph lovers, it would take weeks and maybe not work with all the odd color palettes and relatively low contrast. Even with the extended baselines there's not much eye-popping cheap-3D-movie effects, but you can certainly perceive depth if you look around. Spoiler: The sun is farther away than anything else in these pictures.

The negatives were all scanned individually. There was inevitably going to be some rotating and cropping to match. That and outputting pairs for different viewing methods is easier to do with separate left and right files. The downside of that is that they don't come close to matching color. I balanced the color as close to neutral as I could get and tried to get them to match, but didn't succeed very well. It doesn't matter. It's not real color. It's the inverse of the tone created by the amount of exposure it got. All the foreground detail is nearly invisible in the negative. They're extensively edited in contrast and density. Your brain doesn't care about color balance when making the 3D image, and uses real intelligence to blend the color profiles automatically when you fuse the images into stereo.

The first test mounting was in the living room windows facing due East.

This image illustrates many issues that I observed. These negatives are RC photographic paper mounted to matte board to keep them flat. This one fit a little too well and got bent and slightly wrinkled when removed. The extreme contrast enhancement required to get a viewable image also enhanced all those little defects. The camera is 90 degrees and the sunrise varies 88 degrees from solstice to solstice from this latitude so we're seeing almost the entire track (not quite down to the horizon). Notice that wide cloudy band in winter and spring. You can almost date exactly when the leaves came out. The magnolia is transparent to the sun, including when it was full of white blossoms, until about a month or so ago when the leaves blocked the rather sunny track.

Dr. Jonathon Gutow's 4th floor office in Halsey Science Center, facing southwest with the planetarium below and Swart Hall and the Heating Plant in the distance.

Here's an example of the cameras performing quite differently. (n.b left and right is reversed for these crossed eye pairs. I'm going to be referring to the real position of the camera, which you can probably identify just by looking at it anyway). The left hand camera has a rather clear foreground (for solargraphy), but something happened to the right camera. The stereo view works anyway. This was with the pinhole about 5mm above the axis to maximize the solar track. Note the sun extinguishing before it's quite to the horizon. Still looks pretty bright to your eyes, but the emulsion notices.

Valerie Medina, with whom I had worked with for my workshops at the Trout Museum, let me put cameras in two places where nobody would ever be around them. The rear stairwell is card access from both sides on the fifth floor.

Didn't realize what difference an extra story makes in the building across the plaza. The pinhole is on the axis so this is only about the lower half the entire solar track. Different weirdness in both cameras but your brain picks the best of both to make what you see stereoptically. This was one of the places I couldn't clean the glass from outside. Looked pretty clean but it wouldn't take much of a particle to affect the image right in front of the pinhole. Really convincing patch of "grass" (probably snow) between the walkways.

Facing due west over Houdini Plaza in the fifth floor Artist-in-Residence storage room. Everyone who passes the row of windows with a camera in the public galleries on the third floor photographs this view (or your spouse's fourth floor office, Mike).

I had spent some time and gave up looking for a spot on the North front of the building which might reflect the track in the glass covered building across the street. Pretty cool to see the eastern track perfectly mirrored in the 222 building. Again that extinction near the horizon. One of my wider baselines. No wowie effect, but with some concentration you can see the pillar in the middle of the plaza standing in front of the storefront.

Facing east down the Fox from the storeroom at the Draw. John Adams pulled open the windows and showed me the cinematographer's trick to wash windows with newsprint instead of paper towels. It leaves less lint. 

I've been speculating for months whether there would be a reflection in the river. To our eyes the red railroad bridge stands out prominently, but to photographic paper, it's no different than the dark background.

The southern view over the lock channel from the storage room. I knew this was going to be at the bottom of the bluff so this is another rising front camera.

The bit of building at the right jumps out. You can tell that this side of the channel is closer than the other. Just about made it to the Summer Solstice at the top.

Looking west from Coffee Wizardz. I asked two young women if they minded sliding over just a bit so an old man could reach the cameras without being suspicious. We had a delightful conversation about long exposures, pinhole and solargraphy. As I did with just about everyone else, I showed them a pinhole and opened a camera to give them a look at a raw solargraph.

Again quite a bit of difference in the two images. That should be Lawe Street in the foreground, but we did have couple big storms so there could be a pile of snow in the parking spots for a few days.

I had a bottle of water in my backpack and it spilled all over one of the pairs of cameras. After leaving them to dry and spending the next week celebrating Yule, I mounted them in the upstairs of the garage looking east over the house and driveway on New Year's.

Nice bit of 3D with the house, lanai and neighbor's house. Another example of the oaks suddenly getting opaque with leaves. Surprising to see the garage light, just a few feet from the cameras, fused into the sterescopic image. The red roof shingles, black/snow flat lanai roof, and snow/lawn are all rendered in the same color. More reflection of the western end of the track in the upstairs hall windows and I think I can detect the reflection of the eastern track in the neighbor's upstairs window.

Also on January 1st, two cameras, whose design had been in contention for all the cameras in this project, were mounted in the west garage window. 

This matching pair of lovely Barbara Bixby boxes sort of started the whole thing. Ten centimeters square and six deep with .33mm pinholes for f182 with rather narrow angle for solargraphy of 53 degrees. The pinhole a bit above the axis as well. My original thought was to use this size but reconsidered whether my collaborators would stand something that big blocking their windows and chose to make smaller cameras.

Although I'm pretty sure this is the same paper and the camera is slower, there seems to be a better rendition of detail in the foreground. Amazing how smooth the garden looks. It's either covered with snow or globe flowers and daisies. You can't even see those buildings now through the bushes.

Going wider, in a nod to traditional beer and film can solargraphy, I made two soup cans with a 4x5 sheet of paper curved inside, again .33mm holes about f182, spanning almost 140 degrees.. Note how someone made the pinholes above the axis but not quite at the same level. Cropped identically it doesn't make any difference.

The incredibly robust stereo effect works just fine even with the barrel distortion. I already knew that from previous experiments.

Lastly during all this I thought fondly of my 45mm Stereo 120 Populist and stuck similar papers inside with the rising pinhole opened.

It was placed just sitting between the window and the storm window in the basement.

It pops into 3D probably better than the rest. Elwood and his armillary at the left are barely visible against the tree branches but clearly in front of them in stereo.

I'm not sure if the combination of solargraphy with stereography enhances either, but it was fun and I learned a lot. I have ideas how it could be done better and how to avoid some mistakes. It would be interesting to see the difference from Summer to Winter solstice when there's not as much snow. 

Happy Stereoscopy Day. Thanks to Rebecca, Denis, and Brian for the party! 


  1. This is soooooo cool! Thanks for sharing Nick! I will be showing this to my photo students!
    I get them to do stereo photos with 2 digital cameras then print the cards for them to view.

    1. Thanks. It's pretty easy for your students to make their own stereo pinhole cameras for film. I'd be glad to help out.

  2. These are fantastic!!! I am a big fan of 3D and don't recall ever seeing anything like this!!!