Trichrome Cyanotypes

Hopefully those reading this have seen my previous post about my Bicolor Cyanotype technique. Calling this next step "Tricolor Cyanotype" is a little misleading, because one of the color layers is in fact not cyanotype at all, but rather cuprotype. I've found that other attempts at creating a red layer don't satisfy my "purist" view on creating a fully analog process, or at least one that can be recreated using easily-obtained raw materials.

The chemistry of cuprotypes is similar to that of cyanotypes, where a solution of copper ions reacts to ultraviolet light similar to how an iron solution is used for cyanotypes. The chemistry is remarkably similar too, with ferric ammonium citrate comprising one part of the cuprotype mixture, the other part being copper sulfate. I use a third component, thiourea, but this is not strictly necessary when making cuprotypes. There are many resources available online to learn about cuprotypes, so I won't describe the process here.

Exposure for this technique is a little tricky, as the magenta/red (cuprotype) layer can very easily overpower the other two layers. Additionally, too much exposure on the final cyanotype layer can completely destroy the pretty green tones from the mix with the yellow layer. In general, exposure for the cyan layer is roughly one-third the exposure for the yellow layer. I'm experimenting with exposure for the magenta layer, the exposure above I believe was roughly equal to the exposure for the yellow layer.

Another post will follow soon where I use this technique to make a trichrome print from negatives.

Silver Recovery from Exhausted Photographic Fixer

I've been saving my spent fixer for the past 2 years, after learning how much silver it contains. Rather than sending valuable silver to the hazardous waste facility and gaining nothing from it, I decided to make an attempt at extracting the silver myself.

Whereas there are several methods for precipitating solid silver from the solution of silver thiosulfate, I opted for the cheapest method, the iron reduction reaction. I used 0000 steel wool in a flask of fixer solution on a magnetic stirrer to precipitate the silver.

Left: the flask of fixer with steel wool being added under stirring. Right: the flask after 2 minutes of stirring, with a noticeable amount of silver already having precipitated.

This is approx. how much steel wool I used for
1 L solution. The piece had a mass of ~1.5 g.

After allowing the flask to stir overnight, I placed a magnet onto the side of the flask to collect any remaining iron filings that didn't react. Luckily there were very few, and I was able to decant the silver precipitate into a beaker for washing. I didn't take photos during this process, but I washed the silver several times until the water remained clear between rinses. At first the water was turning yellow during washing, but the yellow color went away after 3-4 rinses. I suspect there were still iron salts in solution.

I collected the dry powder and melted it in a crucible with a little borax for flux. My oxy-propane torch made quick work of it! The silver piece weighed in at 3.17 g.

I'm quite happy with this yield; it seems as though I extracted nearly all the silver from the exhausted fixer. I'm still curious what the theoretical yield is for a 1 L fixer solution, so I think I will make another post in the near future with some calculations to figure out those numbers.

Photoshoot Breakdown #1

 

I recently edited this photo together as a promotional pic for one of my musical ensembles. I'm extremely happy with how it turned out and I wanted to break down how I set up the shot and how I edited the photos together for the final photo.

My original vision was to have the bassoons set out in front of the subjects, larger in scale but still reasonably in focus. A fully black background would allow for blending the four photos together in post, and a single key light would illuminate the subjects with dramatic Rembrandt shadows. Here's a sketch of the setup I used:

The foamcore board was specifically used to ensure that no part of the subject would appear on the left side of the bassoon, and to black out the left edge of the photos to facilitate the final edit. I used a parabolic umbrella to reduce light spill, and with an already black background it was very easy to keep only the subjects illuminated.

A little airbrushing was used between the shots to blend each portrait into the background, but overall the digital edits were not too time-consuming. I like to do as much work in-camera as possible, and save myself the trouble in post!

Bleach Bypass Development with Expired Vericolor III VPS

I recently purchased a couple expired rolls of Kodak Vericolor III VPS 6006 from my local film store, with a couple experiments in mind but low expectations. For this roll I wanted to attempt bleach bypass processing to boost the contrast of this ~30 year old film and to see if my normal B&W fixer is compatible with the C-41 process. I didn't expect the results of my first test to be so good, so I have very little in the way of photos throughout the process. But I did write down my processing steps so I will be able to share how I shot and developed this film.

The Shoot

I loaded the roll into my handy Holga 120N, with the 645 mask in place. The weather was overcast but dry on the day I went out to shoot, but since I was overexposing the film by a stop (80-100ASA) I brought my tripod, light meter, and shutter release cable along to be as accurate as possible with my exposures.

The Development

All development steps were carried out at 38C, the normal temp for C-41. I used the ADOX C-TEC developing kit, having mixed up half a batch and this roll being the last of the 8-roll capacity for half the kit. The fixer I used is the EcoPro Neutral Fixer. Based on what I've read, it is important for the fixer to be neutral and non-hardening so that it is compatible with color negative film.

Here is my bleach bypass process:

1. Film pre-rinse (two rinses in this case)
2. Normal first step C-41 Developer (using instructions from C-41 kit)
3. Water wash to stop development
4. B&W Fixer (5 minutes 1+4 dilution)
5. Water wash several minutes
6. Stabilizer (1 minute, included in my ADOX kit)
7. Final water rinse and hang to dry

The Results

The film base was a little bit dark to the eye, but the negatives appeared well-exposed. I scanned the negs on my flatbed scanner and here are the results. Click the images to view them full-sized.

Conclusions

For a roll of film roughly 30 years old, I think these results are spectacular. I anticipated that some speed would be lost over time, hence my decision to overexpose by a stop. Bleach bypass development adds approximately a stop of speed as well so in effect I have overexposed this film by 2 stops, which appears to have been the perfect exposure. I hope to try this again on unexpired films, which I will probably underexpose by a stop to see if that speed gain is accurate. Since I use the EcoPro Fixer for developing B&W films and papers anyway, I didn't need to purchase a different product for this test. I'm sure other fixers exist that would work with the process too; I'm eager to see if anyone reading this has success with others and if so, please leave a comment.

Thanks for reading, and I hope to see others try this out as well!

Bi-Color Cyanotype Experiments

I was recently inspired by bi-color cyanotypes I saw online, and wanted to take a crack at the process myself. I started simply with solid colors rather than printing with negatives, as the testing process would probably be very long for the latter. I first wanted to see what this process is capable of.

Since I'm sure everyone is familiar with how cyanotypes are made, I won't describe the process in detail. The yellow layer in bi-color cyanotypes come from bleaching a blue cyanotype with sodium carbonate (washing soda). I use 1 tsp sodium carbonate to 1 L hot water, and bleach the cyanotype to completion. My first tests were to determine how much exposure was needed to achieve a satisfactorily yellow layer.

I expose my cyanotypes using a DIY exposure box, lined with UV LED strips. The UV intensity in this box is rather low, so my exposure times tend to be longer. However, I can achieve much greater consistency using my exposure box than relying on sunlight.

From left to right, the exposure times are 30m, 60m, and 90m. Not a huge difference between the three prints at this stage.

The same prints, but fully bleached with sodium carbonate. Despite the initial prints having very similar values of blue, here it's apparent that the overall exposure during the blue step makes a big difference in the yellow value.

On each bleached print I coated another cyanotype layer and exposed all three for 30 minutes. I reduced this exposure time for later prints, but it's still easy to see that the darkest yellow combines best with the blue layer to make green. The fact that the blue and green aren't too different in value makes the prints feel a little flat.

Here is a later print that I'm happy with, with the blue layer receiving less exposure than the prints above. The exposure may have been on the light side, but the color separation is much cleaner:

I have more experiments I'd like to attempt with this technique, so stay tuned for more soon.

Rule of Thirds Gauge

We're all familiar with the rule of thirds, and how we can use it when composing a shot or in the darkroom to elevate a photograph to a masterpiece. I've been finding it very tedious having to measure thirds in the darkroom with a ruler, or cutting appropriately-sized pieces of paper with lines drawn to mark the thirds. I've found an elegant solution to this problem that is both easy to DIY and is adaptable to all sizes of paper.

Inspired by the golden ratio gauges often constructed and used by woodworkers, I took pen to paper to conceptualize what a similar gauge would look like when constructed to give three equal sections. Here are my initial scribblings:

A quick sketch lays out the unit lengths for each arm of
the gauge. Three units for each long arm, two units for
the short arms.

The idea was simple enough, and to my surprise, it was even easier to construct a functional prototype. I sort of brute-forced the solution with super simple math, working with a unit length of 9cm. I'm sure there is a mathematical proof that shows why this device works, but I'm happy enough having sorted it out so simply. The two long arms are 27mm from the pivot point to the tip, and the two short arms are 18mm from their pivots to the tip. All pivot points are 9cm apart. These lengths can of course be adjusted for any sized gauge you wish to construct, as long as the ratios stay the same. Here is a photo of my prototype, made of cardboard and complete with toothpicks to hold everything together:

The gauge functions by first adjusting the two outer points to the desired dimension. When set, the two inner points will show the exact lines that divide the paper into three sections. Easy thirds, without a ruler!

For the final product, I took some black matboard and cut it into 1" strips. I drilled holes with the four pieces clamped together so the holes would be exactly the same on all pieces. The ends were cut to points, and brass brads were used to hold the whole contraption together.

Simplicity, ease of construction, and versatility, this gauge has it all. So far it's proven to be extremely valuable in the darkroom, and I hope to see others start using this tool as well!

Exposure Considerations for the Holga Wide Pinhole Camera (120WPC)

I love the Holga 120WPC. It's lightweight, easy to use, and can yield awesome results in 6x9 or 6x12 formats. It does however have a significant drawback, which is related to focal length and negative size. The focal length (the perpendicular line from the pinhole to the film plane) of this camera is approx. 40mm, but with the 6x12 mask in place the edges of the negative are much farther away from the pinhole than 40mm. I'll illustrate:

The labeled f-stop on the 120WPC is f/135, but as I've shown in my calculation above, the effective f-stop at the edges of a 6x12 negative is f/240. This gives an approximate exposure difference of two stops from the center to the edge. This is a noticeable difference, perhaps not for those who are scanning film, but indeed so for those of us who print in the darkroom. 

Interestingly, this 2-stop exposure difference is retained, regardless of exposure length. Using the exposure suggestions on the back of the 120WPC, I assigned Exposure Values (EV) to each and made exposure calculations, correcting for reciprocity failure where needed:

The recommended exposure times on the
back of the Holga. I assign EV 15, 13,
and 11 to these weather descriptions.

Even when accounting for reciprocity failure (in this case, using P=1.15 for TMax100 film), the adjusted exposure for the edges of the film is approximately 4 times (2 stops) greater than at the center. It's nice knowing that we don't need to make more complex calculation on-scene when using this camera.

With these calculations in mind, we can strategize when using his camera, to either use this shortcoming to our advantage, or selectively place bright subjects off-center so they don't wind up unnecessarily over-exposed. I'll show some example photos of mine below, and caption them with some discussion and explanation.

This photo is scanned from a darkroom print. I slightly dodged the edges to lighten them a bit, but they are still much darker than the middle. In this case, with the sun shining through the trees in the middle, I like the effect and don't mind the dark sides.

A scanned negative. Again, a bright subject placed centered in the frame gets extra exposure and is exaggerated. I think this characteristic of the camera works to great effect here.

Other considerations when shooting with this camera include keeping track of light sources. In most cases, having the light source behind the camera gives the best chance of success. Sometimes though, having the sun in-frame can yield interesting results:

A unique artefact of direct sunlight interacting with the pinhole. Not a bad effect; I was pleasantly surprised seeing this come out of the development tank. This photo is a scanned negative.

On the other hand, sometimes the sun will accidentally shine through a scene, creating unintentional and undesirable flare on the film:

Here, the sun is obviously out-of-frame, but it was shining onto the pinhole nonetheless. The resulting flare spoils the photo for me, so this negative isn't likely to see any action in the darkroom.

In my experience, the only way to be completely sure to avoid these light flares, is to point the camera completely away from strong light sources. I may try modifying a hood that could fit on the camera someday.

I hope this deep dive into the nuances of the 120WPC was of interest! As always, I encourage discussion and very much welcome feedback.

Test Procedure for Enlarging Lenses using Vlad's Test Target

Some of you may have read my previous blog post about comparing the performance of five 50mm enlarging lenses. I'm proud of the work I put into that post, but I wanted to develop a more standardized way of testing enlarging lenses without necessarily having multiple lenses of the same focal length.

In comes Vlad's Test Target (link to his website), a fine-grain mounted negative designed to calibrate camera-scanning rigs. I stumbled upon his product online, and immediately saw how useful it could be in the darkroom to test lens resolution and center-to-corner performance. The test slide is made with Adox CMS Pro II film and has an official resolution of 110 line pairs per millimeter (lp/mm). Details this fine rival the resolution achievable on fine-grain films such as Kodak TMax100¹ and Ilford Delta 100. Adox CMS Pro II is incredibly fine-grained and is capable of resolving up to 800 lines per millimeter (l/mm), so the limitation of the film stock itself will have no effect on this experiment. The design and principle behind the test pattern can be found here. As of now I only have the 35mm version of this slide, which I don't plan to use to test lenses longer than 80mm (Vlad makes test targets in larger sizes).

Vlad graciously provided me with this high-quality scan from his test slide, which shows the test lines alongside their corresponding resolution in lp/mm. Note how small this area is on the slide itself (1.5 x 1.3mm); it can be viewed in some of my test prints below. The slide was scanned by Dominique Ventzke at High End Scans.

To prevent this post from getting too lengthy, I focused on testing only two lenses that in my opinion are on opposite ends of the quality spectrum: the EL-Nikkor 50mm f/2.8 and the EL-Omegar 50mm f/3.5. My hope in testing these particular lenses was that I would see similar results in center sharpness but noticeably different results in the corners. The EL-Nikkor was tested at print sizes of 5x7, 8x10, and 16x20. The EL-Omegar was only tested at 16x20, to most clearly illustrate the difference between the two lenses. I did not print full sheets at each of these sizes (only for the 5x7), but rather adjusted the enlarger to the proper size, and printed a small area of the test slide that contained the area I wanted to analyze. I made all prints at f/8, both to simplify the procedure and to give the lenses their shot at the most "ideal" printing aperture.

Each of the resulting prints was scanned at 1200dpi on a flatbed scanner. At this resolution, the test target and the lenses being used are the limiting factor rather than the resolving capability of the scanner.

5x7 print of the test slide using EL-Nikkor 50mm at f/8.

The 5x7 print was, as expected, very sharp and the details were all excellently resolved. I wasn't expecting to push any limits at this size, just needed a straight print. The corner details appear to be exactly as sharp as the details in the center. When I zoom into the scanned print, I can see slight differences in sharpness, but the difference is indiscernible to the naked eye.

    

Enlarged now to 8x10, much finer details can be seen. The smallest lp/mm are more discernible, but not yet fully resolved.

 

At 16x20, my enlarger has reached its maximum height without having to adjust it to project onto the floor. The very smallest details are visible now, and the resolution limit of the test target has been reached. The corners are quite obviously softer than the center, but still very suitable for printing.

And here are the results from the EL-Omegar. In my last discussion on this lens, it mainly showed inconsistencies between aperture settings and overall poor sharpness at all but the most ideal apertures. These prints reveal another interesting characteristic of this lens, particularly in the corners. The center is arguably as sharp as that of the EL-Nikkor, especially at f/8, which is expected to be the sharpest. What was interesting was the distortion that can be seen in the corners. The test lines that are tangential to the lens appear decent, but significant blurring can be seen in the radial lines.

Cropped in from the previous photo; the difference
between radial and tangential lines is very obvious.

I'm no optical engineer, but I can only assume the effect we see here is a factor of lens design, and not of anything about my setup. I would always expect a lens to lose some sharpness in the corners, but this is almost beyond usable. The distortion blurs details in the 15-17 lp/mm range, which would considerably reduce resolution when printing even the grainiest films.

In conclusion, I'm very satisfied with the results I was able to obtain with Vlad's Test Target. It is a quality product, perfectly suited for darkroom use, and highly recommended by me. I believe the results I obtained are very clear and the differences between these two lenses thoroughly demonstrated. I always welcome feedback of any kind, and hope that this post is of some use to those reading it!

Thank you.

1. The official datasheet for TMax100 lists a resolution of 200 lines/mm. Converting to line pairs per mm gives 100 lp/mm, barely less than the resolution limit of the test target.

How to Develop Found Film

I'm frequently searching thrift stores and camera shops for old equipment, and occasionally I'll find a camera with an exposed roll still inside. The packaging reveals the type of film and usually the development process needed (in the case of color films). But long-expired films are often fogged or the development process is obsolete. I'd like to share how I process found film at home and get consistent results.

My development process is very simple, and uses HC-110 developer:

• 1+90 dilution HC-110
• 18 minutes development
• Agitate for the first 30s, then for 10 seconds every 3 minutes thereafter

This development will work for old color films, but naturally will result in low-contrast B&W images. Many color development processes have been replaced with modern processes (for example E-6 has replaced E-3 and E-4), so white attempts with modern color chemistry could be employed, the method described above is a cheap and quick way to get results.

Once developed, scanning the negatives can be tricky, especially if they are severely fogged. I scan using an Epson V500, and following a preview scan will adjust the brightness and contrast until I can obtain a decent image. Below are come comparison images to show the condition of the negatives, and the best result I was able to get while scanning:

You can see that the negative here is in somewhat bad shape, but for film that was developed after 60 years, the result is actually quite nice!

This example is likely from the 80s, so while the film had fogged somewhat, the latent image was still in good shape and the film base hadn't been exposed to fungus or moisture.

Here you can see what good scanning is capable of. On the left above you see a cellphone photo of the negative, with an incredibly faint image. On the right, my final scan after manipulating settings in the scanning software. The film was in bad shape, but the result is still decent!

A particularly bad example, from
the same roll as the last photo.
The subject can still
be identified though!