Making a Pinhole Attachment for an SLR

Last autumn, after a few years away from it, I got back into 35mm stills photography. I’ve been reading a lot of books about photography: the art of it, the science and the history too. I’ve even taken a darkroom course to learn how to process and print my own black and white photos.

Shooting stills in my spare time gives me more opportunities to develop my eye for composition, my exposure-judging skills and my appreciation of natural light. Beyond that, I’ve discovered interesting parallels between electronic and photochemical imaging which enhance my understanding of both.

For example, I used to think of changing the ISO on a digital camera as analogous to loading a different film stock into a traditional camera. However, I’ve come to realise it’s more like changing the development time – it’s an after-the-fact adjustment to an already-captured (latent) image. There’s more detail on this analogy in my ISO article at Red Shark News.

The importance of rating an entire roll of film at the same exposure index, as it must all be developed for the same length of time, also has resonance in the digital world. Maintaining a consistency of exposure (or the same LUT) throughout a scene or sequence is important in digital filmmaking because it makes the dailies more watchable and reduces the amount of micro-correction which the colourist has to do down the line.

Anyway, this is all a roundabout way of explaining why I decided to make a pinhole attachment for my SLR this week. It’s partly curiosity, partly to increase my understanding of image-making from first principles.

The pinhole camera is the simplest image-making device possible. Because light rays travel in straight lines, when they pass through a very small hole they emerge from the opposite side in exactly the same arrangement, only upside-down, and thus form an image on a flat surface on the other side. Make that flat surface a sheet of film or a digital sensor and you can capture this image.

 

How to make a pinhole attachment

I used Experimental Filmmaking: Break the Machine by Kathryn Ramey as my guide, but it’s really pretty straightforward.

You will need:

  • an extra body cap for your camera,
  • a drill,
  • a small piece of smooth, non-crumpled black wrap, or kitchen foil painted black,
  • scissors,
  • gaffer tape (of course), and
  • a needle or pin.

Instructions:

  1. Drill a hole in the centre of the body cap. The size of the hole is unimportant.
  2. Use the pin or needle to pierce a hole in the black wrap, at least a couple of centimetres from the edge.
  3. Cut out a rough circle of the black wrap, with the pinhole in the middle. This circle needs to fit on the inside of the body cap, with the pinhole in the centre of the drilled hole.
  4. Use the gaffer tape to fix the black wrap tightly to the inside of the body cap.
  5. Fit the body cap to your camera.

The smaller the pinhole is, the sharper the image will be, but the darker too. The first pinhole I made was about 0.1-0.2mm in diameter, but when I fitted it to my camera and looked through the viewfinder I could hardly make anything out at all. So I made a second one, this time pushing the pin properly through the black wrap, rather than just pricking it with the tip. (Minds out of the gutter, please.) The new hole was about 0.7mm but still produced an incredibly dark image in the viewfinder.

 

Exposing a pinhole image

If you’re using a digital camera, you can of course judge your exposure off the live-view screen. Things are a little more complicated if, like me, you’re shooting on film.

In theory the TTL (through the lens) light meter should give me just as reliable a reading as it would with a lens. The problem is that, even with the shutter set to 1 second, and ISO 400 Fujifilm Super X-tra loaded, the meter tells me I’m underexposed. Admittedly the weather has been overcast since I made the pinhole yesterday, so I may get a useful reading when the sun decides to come out again.

Failing that, I can use my handheld incident-light meter to determine the exposure…. once I’ve worked out what the f-stop of my pinhole is.

As I described in my article on aperture settings, the definition of an f-stop is: the ratio of the focal length to the aperture diameter. We’re all used to using lenses that have a clearly defined and marked focal length, but what is the focal length in a pinhole system?

The definition of focal length is the distance between the point where the light rays focus (i.e. converge to a point) and the image plane. So the focal length of a pinhole camera is very simply the distance from the pinhole itself to the film or digital sensor. Since my pinhole is more or less level with the top of the lens mount, the focal length is going to be approximately equal to the camera’s flange focal distance (defined as the distance between the lens mount and the image plane). According to Wikipedia, the flange focal distance for a Pentax K-mount camera is 45.46mm.

So the f-stop of my 0.7mm pinhole is f/64, because 45.64 ÷ 0.7 ≈ 64. Conveniently, f/64 is the highest stop my light meter will handle.

The website Mr Pinhole has a calculator to help you figure this sort of stuff out, and it even tells you the optimal pinhole diameter for your focal length. Apparently this is 0.284mm in my case, so my images are likely to be quite soft.

Anyway, when the sun comes out I’ll take some pictures and let you know how I get on!

Making a Pinhole Attachment for an SLR

Creating “Stasis”

Stasis is a personal photography project about time and light. You can view all the images here, and in this post I’ll take you through the technical and creative process of making them.

I got into cinematography directly through a love of movies and filmmaking, rather than from a fine art background. To plug this gap, over the past few of years I’ve been trying to give myself an education in art by going to galleries, and reading art and photography books. I’ve previously written about how JMW Turner’s work captured my imagination, but another artist whose work stood out to me was Gerrit (a.k.a. Gerard) Dou. Whereas most of the Dutch 17th century masters painted daylight scenes, Dou often portrayed people lit by only a single candle.

“A Girl Watering Plants” by Gerrit Dou

At around the same time as I discovered Dou, I researched and wrote a blog post about Barry Lyndon‘s groundbreaking candlelit scenes. This got me fascinated by the idea that you can correctly expose an image without once looking at a light meter or digital monitor, because tables exist giving the appropriate stop, shutter and ISO for any given light level… as measured in foot-candles. (One foot-candle is the amount of light received from a standard candle that is one foot away.)

So when I bought a 35mm SLR (a Pentax P30T) last autumn, my first thought was to recreate some of Dou’s scenes. It would be primarily an exercise in exposure discipline, training me to judge light levels and fall-off without recourse to false colours, histograms or any of the other tools available to a modern DP.

I conducted tests with Kate Madison, who had also agreed to furnish period props and costumes from the large collection which she had built up while making Born of Hope and Ren: The Girl with the Mark. Both the tests and the final images were captured on Fujifilm Superia X-tra 400. Ideally I would have tested multiple stocks, but I must confess that the costs of buying and processing several rolls were off-putting. I’d previously shot some basic latitude tests with Superia, so I had some confidence about what it could and couldn’t do. (It can be over-exposed at least five stops and still look good, but more than a stop under and it falls apart.) I therefore confined myself to experimenting with candle-to-subject distances, exposure times and filtration.

The tests showed that the concept was going to work, and also confirmed that I would need to use an 80B filter to cool the “white balance” of the film from its native daylight to tungsten (3400K). (As far as I can tell, tungsten-balanced stills film is no longer on the market.) Candlelight has a colour temperature of about 1800K, so it still reads as orange through an 80B, but without the filter it’s an ugly red.

Meanwhile, the concept had developed beyond simply recreating Gerrit Dou’s scenes. I decided to add a second character, contrasting the historical man lit only by his candle with a modern girl lit only by her phone. Flames have a hypnotic power, tapping into our ancient attraction to light, and today’s smartphones have a similarly powerful draw.

The candlelight was 1600K warmer than the filtered film, so I used an app called Colour Temp to set my iPhone to 5000K, making it 1600K cooler than the film; the phone would therefore look as blue as the candle looked orange. (Unfortunately my phone died quickly and I had trouble recharging it, so some of the last shots were done with Izzi’s non-white-balanced phone.) To match the respective colours of light, we dressed Ivan in earthy browns and Izzi in blues and greys.

Artemis recce image

We shot in St. John’s Church in Duxford, Cambridgeshire, which hasn’t been used as a place of worship since the mid-1800s. Unique markings, paintings and graffiti from the middle ages up to the present give it simultaneously a history and a timelessness, making it a perfect match to the clash of eras represented by my two characters. It resonated with the feelings I’d had when I started learning about art and realised the continuity of techniques and aims from me in my cinematography back through time via all the great artists of the past to the earliest cave paintings.

I knew from the tests that long exposures would be needed. Extrapolating from the exposure table, one foot-candle would require a 1/8th of a second shutter with my f1.4 lens wide open and the Fujifilm’s ISO of 400. The 80B has a filter factor of three, meaning you need three times more light, or, to put it another way, it cuts 1 and 2/3rds of a stop. Accounting for this, and the fact that the candle would often be more than a foot away, or that I’d want to see further into the shadows, the exposures were all at least a second long.

As time had become very much the theme of the project, I decided to make the most of these long exposures by playing with motion blur. Not only does this allow a static image – paradoxically – to show a passage of time, but it recalls 19th century photography, when faces would often blur during the long exposures required by early emulsions. Thus the history of photography itself now played a part in this time-fluid project.

I decided to shoot everything in portrait, to make it as different as possible from my cinematography work. Heavily inspired by all the classical art I’d been discovering, I used eye-level framing, often flat-on and framed architecturally with generous headroom, and a normal lens (an Asahi SMC Pentax-M 50mm/f1.4) to provide a natural field of view.

I ended up using my light meter quite a lot, though not necessarily exposing as it indicated. It was all educated guesswork, based on what the meter said and the tests I’d conducted.

I was tempted more than once to tell a definite story with the images, and had to remind myself that I was not making a movie. In the end I opted for a very vague story which can be interpreted many ways. Which of the two characters is the ghost? Or is it both of them? Are we all just ghosts, as transient as motion blur? Do we unwittingly leave an intangible imprint on the universe, like the trails of light my characters produce, or must we consciously carve our mark upon the world, as Ivan does on the wall?

Models: Izzi Godley & Ivan Moy. Stylist: Kate Madison. Assistant: Ash Maharaj. Location courtesy of the Churches Conservation Trust. Film processing and scanning by Aperture, London.

Creating “Stasis”