Friday, December 15, 2017

A Pinhole Lab Camera

Preface

I have this fantasy of a pinhole class.  It could be a five day camp or a regular school class for several weeks. I think it would have to be at least junior high school, but it could be with senior citizens.  I'm really done with half day workshops. For those I always seem to end up spending all my time identifying light leaks and fixing them and it ends up just being a technical demonstration and nobody gets to play with pinhole photography.

I started getting really serious about pinhole when I worked with the university's science outreach department to create a program using pinhole photography as an example of physics and chemistry concepts.  I'd still like to include that sort of thing and I can imagine it being a supplement to a variety of science, art or general liberal studies classes, but I'd like it to concentrate on iconic experiences in pinhole photography, although a lot of this is going to inform one's practice of lensed photography.

Building your own camera from raw materials is one of the iconic experiences of pinhole photography,  I had a tenured History prof tell me last year that building a pinhole camera in Junior High School was one of the most memorable experiences of his education.

A New Camera

If I ever got the chance to do this extended curriculum, I've been developing the camera I think I'd use. (n.b. the cameras in the picture above are prototypes with minor variations)

In previous workshops I used a camera design I was given by Ruth Thorne-Thomsen.  It was pretty quick and easy to build and load. I had fourth graders successfully do it without much trouble. It was slightly prone to light leaks, but in predictable places and usually easy to fix with tape. One fifth grader who had been in a workshop as a fourth grader the year before remembered that most problems could be fixed with more tape. It could be built with several distances from pinhole to paper, but it was less confusing if they all made identical cameras and although I used to bring examples of shorter and longer cameras and let the kids use them, everyone didn't get to experiment. The design's biggest weakness is the dependence on a supply of black opaque photographic tape, which is a little expensive and has to be ordered from a photo or art supply house.

I also had kids build curved cameras out of La Choy Noodle cans because that non-flat film plane is so critical a concept in pinhole photography, but those plastic lids are irritatingly hard to make light tight.

For this new camera, I'm sticking with a one-shot camera loaded with photographic paper, for the budgetary aspects and for learning objectives. Timely feedback is a critical factor in learning, especially if it's matched to a protocol where you try to predict (or imagine) how something will work out. Having to go back to the darkroom gives the student just enough time to wonder about that sort of thing but it's short enough to remember what they did before finding out if it worked.

It's the same printed-template-glued-to-cardboard-and-folded-and-glued-together concept as most of my other cameras.

The new camera has multiple formats that would allow each participant to experiment with several parameters:
  • pinhole to film distance (what would be focal length on a lens), 
  • aspect ratio and film size, 
  • adjusting the field of view by changing where the pinhole is in relation to the center of the film plane (rising and falling front) and 
  • curvature of the film plane.  
It's also set up so the size of the pinhole could be changed easily.

Formats:

It's designed around a format of 2½ x 4 inches (64 x 102mm).

The basic concept is that's an even division of an 8 x 10 inch (20.3 x 25.4cm) sheet of paper - one eighth.

In almost every school environment budget is going to be an issue.

That may seem a little small, but it's bigger than 6x9cm on 120 film or Instax prints.

It's aspect ratio - 5:8 - is just a hair wider than 35mm's 2:3 and it's pretty close to the 9:16 screen most people spend a lot of time looking at on laptops and HDTV.

An advantage for my lab camera is the ratio is great enough that the dimensions of a box to accommodate that shape, if you put a pinhole on two sides, can have two distinctly different pinhole to film distances with all the f-ratio, angle of view, vignetting and perspective of depth principles that implies.

The box is approx. 4 x 4 x 2½ inches. That allows 4 inches to the pinhole on the rectangular end (34.5 x 52 degrees - about a 35mm 35mm equivalent), and 2.5 inches with the pinhole on the square side. (53.5 x 77 degrees, about a 23mm 35mm equivalent).

For the 2½ inch pinhole distance, I put the pinhole and the paper toward the end opposite the opening so it would be easy to load accurately in the darkroom.





For the 4 inch distance the paper would go in the removable cover. I can hear you thinking how that is just an invitation to a light leak. The body includes a light trap the cover fits into, which I'll detail later on.




Of course by turning the camera on it's side you also have vertical options.


Since you've got a four inch square available on the short side of the camera, if you put an extra pinhole right in the middle of that side, you've got a 4 x 4 inch square format.





I know I've just blown the even divisions of an 8 x 10 sheet of paper, but if you're going to make contact prints (an iconic pinhole experience) you'll need lots of test strips, and who says you can't just put a 2 inch negative in if you want to. (What would that do to the angle of view?)

Curved film planes and panoramic formats are other critical concepts in pinhole photography.

If you put a little ridge on the side of the camera a half inch from the front, a 2½ x 6 inch piece of paper held between the camera back and those ridges forms very close to a 2½ inch radius curve.




You could also do this with a 4 x 6 inch piece of paper.

Now,  make sure your half inch ridge is only 2½ inches high and put another ridge across the 2½ inch side, 1½ inches down the back. If you place a 2½ x 6 inch piece of paper between those ridges and the camera back,  you've got kind of an odd curve varying from about 2¼ to 4 inches. That's definitely not the perfect radius which is kind of expected of a curved film plane camera.  And the pinhole says: "I don't care, it doesn't matter how far from the film plane I am, it just changes the exposure."



This would be kind of interesting math to see if the increasingly reduced area of the foreshortened ellipse of the pinhole as you view from the side would compensate for the technically faster f-ratio at the sides.

Even with this elongated format, you can turn it to vertical.


Rising and falling front.

The entire image cast by the pinhole and how the image appears when cropped to different parts of that circle is a concept easily explored in pinhole photography. If you have view camera experience, I'm speaking here of rising and falling fronts.

Just quickly, if the pinhole is above the center of the film plane, it will somewhat appear that the camera is getting a higher point of view.  Since pinhole is all about straight lines it's easy to demonstrate that you're looking in a different direction.  Since no focusing is going on it doesn't matter that this might be in a different plane. The pinhole doesn't care. Again, exposure will vary across the image, and you may see some vignetting, but those are easily managed variabilities that can be handled in making the positive. Probably the most common use of this function is to photograph a tall building without tilting the camera back so it doesn't look like it's falling over backward. If the camera is level, the apparently higher angle of view will still have parallel verticals. Another place you'd like to use this is landscapes with those curved film planes where you want to keep the horizon level so the distortion of the curved film plane isn't so distracting.  You can change where that horizon is in the composition with a rising or falling front. (Are you thinking Rule of Thirds?)

If you make another pinhole above the one in the middle, that's just like a rising front. If you've got the rising front extra pinhole, if you turn the camera over, it's a falling front. By the way, the axial pinhole of the 4 inch square is the rising/falling pinhole of the 2½ x 4 inch format, and vice versa.

Here are the three variations of the 2½ x 4 inch format at 2½ inches.

Rising front.


The on-axis pinhole.


And with the camera turned over, the falling front.


By taking a rising and falling front picture from the 4 x 4 inch and pasting them together you can get a 4 x 5½ inch format.


And of course you can do it with verticals, and the curved film planes, or shift to the left and right rather than up and down.  There's over a hundred variations.

Each one of these apertures would have a separate piece of tape as a shutter (which is another iconic pinhole experience).

Six Pinholes?

If we do this for both distances to the pinhole for both vertical and horizontal, that makes six pinholes. I can just hear you thinking: "Wait a minute, Nick, you're going to have these kids drill six pinholes?"  I propose making .5mm pinholes by completely piercing thin metal to the diameter of a #10 quilting needle. My reason is that it's so easy. I have never encountered someone who couldn't make a nearly perfect .5mm pinhole.  I've only seen about three that required a second try (Drill - don't just push).  This includes kids as young as third grade.

Here are a .5mm Gilder electron microscope aperture and the six pinholes I made in under ten minutes that were used to make the pinhole images in this post.



I know that this is larger than the calculated optimum for both pinhole distances we're working with but it's the smallest sewing needle I can find. I think the ease of making them and the predictability of the aperture supersedes the need for the "sharpest" pinhole possible.  I don't think "as sharp as possible" should be an objective of a beginning pinhole class. This is a chance to explore the pinhole aesthetic.

I know about micro-drills and electron microscope apertures, but drilling a pinhole with a needle is probaby the most iconic pinhole experience.

These oversized pinholes also have the advantage of speed.  At 2½ inches it's f127 and the 4 inch option is f203.  With photographic paper, we're looking at sunny day exposures of between 15 and 30 seconds, and cloudy day exposures of 2 to 5 minutes. I've never had problems with people dealing with long exposures, but let's just say you can get more done with shorter exposures.

The camera design includes mounting the pinholes on a removable holder, so if you have students who can deal with the extra trouble of drilling and measuring smaller pinholes, or slits, or zone plates, it's easy to change them to experiment, and you don't have to change all six at once.

The sun is a vengeful benefactor

Most bad experiences in a pinhole workshop are caused by light leaks from the sun sneaking through the joint where you open the camera to load paper or film.

When I made the moderately telephoto camera in a plain brown wrapper, and I cut down the camera back to make it easier to open, it occured to me if I cut a strip off the part I removed and glued it to the front box right up against the closed back, and then glued a strip with an overhang over it that the camera back would slide under, I would have a pretty reliable light trap that was easy to open and close.  Cutting off part of a box after it's been glued together is a bit of a hassle, so I added a separate part to accomplish this.


Quandaries

It takes some time and careful work to make. This camera requires proper glueing to stay together, and that means you have to wait for a while between at least four steps.  With Aleens Fast Drying Tacky Glue, I made one in around three hours working nearly continuously, letting parts dry while I cut out and folded the next part.  With regular white school glue you'd want those drying periods to be several hours.  Aleens Fast Drying glue costs four times as much as school glue.

It takes a 12 inch square of cardboard for the largest part. Only the largest economy size of breakfast cereal when opened flat is big enough, and 24 and 30 packs of canned beverages work.  Poster board from art supply stores or Walgreens for that matter come in 22 x 28 sheets that would be more than adequate for a camera (Get black).

It can all be done with scissors except for cutting out the holes for the pinholes which have to be done with a craft knife. Craft knives are dangerous.  How young a kid can you trust with an Xacto knife? I have used hollow point punches to make these holes, but they take a pretty good whack with a mallet to cut the hole.  Paper and card stock don't tolerate drills very well.

Is it all too much?  Would students just be bewildered? Some might, but if they can figure out video games, none of this should be too hard, and it's all reinforced by hands-on/minds-on experience with the concepts.

I'm wondering how long it would be before they came up with this:



or this:


I think I've got the template worked out now, and I'm working on a post on building and using the camera.

I'd love to hear some feedback.


4 comments:

  1. Nick:
    You have given this considerable thought, and have spent considerable time developing the platform. I would love to try this out in a classroom situation. I am still a year away from retirement, so I can’t do it during the workday yet, but I could do an evening thing. Workshops that I have taken at MCAD have been 2 to 2 1/2 hours weekly for ten or twelve sessions. I think that there is enough to learn to fill this much time. The only trouble with the evening session model is that there would not be enough daylight for shooting. When one of my kids was in fifth grade I tried to talk her teacher into a pinhole workshop, but the limitation there turned out to be construction of a temporary darkroom. This would be a perfect workshop for a facility that teaches film photography and is already equipped with a darkroom. Of course, a closet with a counter top or the top of a wheeled cart would do the trick if there is a nearby water supply. I look forward to you camera building instructions.

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  2. That night class might be a challenge. Magnesium powder?

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  4. Nice design, Nick; I like the idea of multiple focal lengths and image formats in one box.

    If you line the area around each pinhole with duct tape (or some material that accepts gaffers tape without tearing) you can use just one pinhole at a time, covering the other unused pinhole mounts with opaque gaffers tape.

    I like the idea of the band around the middle that covers the gap under the lid. I'd make it a bit wider, so it slides up and down and gives more coverage without so easily slipping off.

    It's more expensive, but black gaffers tape instead of glue enables cameras to be built without waiting for the adhesive's curing time. It'd be a tradeoff between materials cost and time.

    I've been developing smaller sized formats in steel 35mm development tanks. Just measure the inside depth of the tank, that's the limit to the small dimension of your negative. The paper is wrapped around the inside wall of the tank and adhered with artists tape. The negative can be loaded from camera to tank inside a changing bag, no darkroom needed. Then use a homemade rotary drum mount (a piece of plywood with 4 small caster wheels bolted on), enabling the steel tank to be rolled on its side on the wheels for processing. They only require about 50-100mL of liquid for processing. Use small clear disposable plastic cups for the chemicals and water rinses. Mark the 100mL level on the side of the cups with a permanent marker, so no graduated cylinders needed.

    Look forward to how this project progresses.

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