Pinholing, Episode 2: Construction
In this post, I’m going to go over how I built my 8×10 wooden box pinhole camera. It’s really simple, but there were a bunch of small hurdles to jump over once I actually got going. It’s a really simple design, just enough to get the job done while not giving me any nightmares that my camera will disintegrate in the environment (I’m looking at you, foam core…)
First off, I had to make the box. I had six pieces of 12″x12″x1/4″ craft plywood to work with, and I knew that I wanted my “focal length” to be 8 inches (I trust my international listeners to be able to do some conversions, but for reference, I had 254 mm square wood panels and a desired focal length of 203 mm. Those are your freebies.) Again, I’m putting “focal length” in quotes since it’s the distance from the aperture (i.e., pinhole) to the film plane; there’s not really a focus method. I wanted to get the distance as close as possible to 8 inches, so I cut all the sides of my box to be a hair under 8 inches – there is a tiny bit more distance to cover thanks to the structure of the film holder.
It’s important to make a few notes here… When working with wood, you have to take the thickness of the wood into account. For example, my camera is 8.5 inches thick, but the internal distance (pinhole to film plane) is pretty close to 8 inches. Also, I started off with having an 8×10 film holder that I could use as a guide. The front and back of the camera were cut to fit the film holder exactly; I didn’t even make measurements with a ruler.
Anyway, with all the pieces cut to size I started gluing them together to make a wooden box. I used one of the most awesome adhesives around, Gorilla Glue. It’s an expanding polyurethane glue, and it’s strong as hell. Of course, it’s got some special instructions to make it work the way you want to, so make sure you read them carefully. I used some scrap wood to thin out the glue that I had squeezed out, and I used some 90-degree clamps to hold things in place while the glue cured.
Before you knew it, I had a complete box with one side left free where the film holder would go. In the front, I drilled a relatively wide hole so that the pinhole had access to a very wide-angle cone of view. That is, if the wood is too thick or the hole is too small, the pinhole would suffer from “tunnel vision.” I’m guessing that my hole offers 90 degrees or more for the pinhole, which is plenty for my fairly long (for pinhole, anyway) 8 inch focal length. Finally, I spray-painted the entire interior of the camera a non-glossy black. You really want to kill the light as much as you can.
The fine folks at Lenox Laser shipped the pinhole in a very neat, well-sealed plastic square holder. Rather than try to tape the fragile pinhole to the inside of the camera, I just drilled a hole in one half of this plastic holder and used it as a mount. I was therefore able to tape the whole thing to the inside of the camera with gaffers tape without even touching the pinhole (not counting removing it so I could drill that hole). I also (after my first test with the camera) put some gaffer’s tape around all the seams to cut down on light leaks from the edge of the box.
With the interior all prepared, the trickiest thing was to actually get the film holders to stay in place. For my first test, I was way too giddy and anxious, so I held the holder and back (a simple piece of wood) on with painter’s tape. Definitely not a long-term solution, even if the tape wasn’t the primary cause of my light leaks. I wanted some sort of “spring” back, so I got the ingenious idea of getting some black waistband elastic and making some loops that I could just strap around the camera to hold everything together. Of course, what I failed to remember was that I’d be setting the camera up on its side, and gravity would make the back sag, to the point of letting light in.
Fortunately, there was some scrap wood laying around (wood that had even been used to test a router, so it was rounded on one edge), so I cut three stop blocks. Thus, the back couldn’t slide around in any of the three directions I didn’t want it to. It can still move towards the “top” of the camera (the side where you pull darkslides out) and it can also fall out, but the elastic prevents that from happening. The downside is that now I can’t set the camera easily on the ground or a table, but I imagine that wouldn’t make for very good photographs.
The last thing to include was a pair of tripod mounts (one for landscape orientation, one for portrait), which simply involved putting 1/4″ x 20 nuts in a pre-drilled hole and securing the edge with Gorilla Glue.
After a simple staining and polyurethaning (yes, it’s apparently a word), I considered the camera complete. But how would it fare out in the field?
(That’s my poor attempt at a cliffhanger ending, btw)
Pinholing, Episode 1: Design
I’ve wanted to build a pinhole camera for a while now. And I know what you’re thinking. Oatmeal boxes, Altiods tins, and blurry images. But I have fallen in love with pinhole cameras like those produced by Zero Image, Lensless, and Leonardo. These are quality wooden boxes capable of producing really sharp images. And they can also be really expensive if you want to do large format. $300+ for a Leonardo 8×10, $200+ for a Lensless 8×10 camera, and $120-$270 for Zero Image 4×5′s, and all at fairly wide angles. Then, there’s the new Harman Titan camera, a 72mm 4×5 pinhole camera that should retail for around $200 soon. The images I’ve seen from it (thanks to Filmwasters’ Leon Taylor) are truly remarkable.
I’ve been thinking, what’s the big deal? All I want is a sturdy wooden box that will take an 8×10 film holder on one side and hold a pinhole at the other side. So, I decided that maybe building my own quality pinhole camera could be an option. But then, there’s that word: “quality.” Everything that I like about these cameras I’ve listed is their wonderful sharp (relatively speaking) quality. You can get a fantastic image from the cameras I’ve mentioned, while all the DIY cameras I’ve seen have left a lot to be desired. It frequently turns into a competition of who can build a pinhole camera out of the wackiest materials, rather than taking a look at how to perfect a design. So, this is my goal:
Design and fabricate a wooden pinhole camera that will make as perfect an image as possible on 8×10 film in an appropriate film holder.
Now, you need to understand a tiny bit of optics to get pinhole design. By restricting the aperture of a hole down so far, you’re only using light rays that are bouncing straight off the subject and onto the film plane in a direct path. (see Wikipedia for example) However, if the hole is too small, you start getting too much diffraction due to the way light bends. I feel unqualified to explain further, but suffice to say that we need an optimum pinhole diameter. Lord Rayleigh, acoustics genius, came up with an awesomely simple formula,
pinhole diameter = 1.9 * square root(focal length * light wavelength)
which will give an optimum pinhole diameter. Also, there are a number of simple online calculators such as this one which will just spit out a number, using both inches and mm. So, it’s decision time. How far away is the pinhole going to be? I decided to start by looking at view angle
As far as view angle is concerned, I love my Nikon 24mm lens. A 24mm lens on a 35mm camera gives you a diagonal angle of view of 84 degrees. 28mm, another great focal length, gives you 75 degrees. So, by my thinking, if I can keep the angle of view around this size, I should have a nice image without too much distortion of perspective. I made a spreadsheet and found that, for 8×10 film, a “focal length” of 8 inches (I use quotes, because no focusing is going on in pinhole photography) gives a diagonal angle of view of 77.35 degrees. Equivalent to 26mm on a 35mm camera. Perfect – gives me a wide angle without going into “weirdness” territory.
Having settled on a third dimension for the camera, I got two calculations of the optimal pinhole size. Rayleigh’s formula says I should have a pinhole of 635 microns (or 10^-6 meters) at 8 inches away, while the “Mr. Pinhole” calculator at the earlier link suggests 601 microns. I erred on the slightly smaller side and ordered a 600-micron pinhole from Lenox Laser in Maryland. Apparently the tolerances are smaller than 5%, so I should be getting something worlds better than if I tried punching my own hole through a thin bit of brass. As an added bonus, I know that my camera will be permanently set to f/339.
So, having ordered a pinhole, I’ve started cutting up six pieces of wood I bought at the local craft store. I’ve decided to just glue some tabs on the back piece (the film holder side) as well as the two side pieces, then use elastic on these tabs to hold the back in place. It’s a poor man’s spring back, essentially. I’ll also try things like putting two 1/4×20 nuts in two sides, so that I’ll have a tripod mount for both a horizontal and landscape orientation. If preliminary tests go well, I’ll try my hand at installing a rotating shutter, much like you can find on the Lensless cameras.
But I’m getting ahead of myself. Once I get home, I’ll take some snapshots to show you the woodwork before I start using Gorilla Glue (honestly some of the best adhesive around) to put the box together. Unfortunately, the glue requires a lot of clamping force and a long time to dry, so I’ll probably be gluing one edge at a time for a few days. I might even get my pinhole in the mail before I’m ready to install it.
Anyway, I’m hoping that this whole project will generate plenty of content for a blog that I feel has been neglected for far too long.
