As a roll of film moves across the film plane: making a slit-scan camera

This is the story of how I came to own a custom-built 35mm slit-scan photography camera and how I set about using it to capture the streets of São Paulo.

This story begins in June 1994 when Professor Andrew Davidhazy from Rochester Institute of Technology went to São Paulo, Brazil, to teach a workshop. The workshop was about special effects in photography, obviously analog then.

One of his students was local photojournalist Claudio Machado who, inspired by the workshop, decided to build himself a slit-scan photography 35mm camera (below) similar to the one Davidhazy showed during the workshop.

Claudio Machado - Sambadromo
Claudio Machado – Sambadromo

Claudio sourced some aluminum to build a frame with grip, he also went after a timing belt, a gear box belonging to kitchen appliance, a high torque 12v motor and a Linhof multi-finder. He also found a huge battery, a 12v lead-acid monster to power his rig he carried inside a camera bag.

All this would surround a Nikon FA camera with a slit placed at the film gate in order to shoot some hand-held slit images. He went on to capture many images during São Paulo’s Carnival parade the year after in 400 ISO black and white negative film.

Building a slit-scan camera

There’s some excellent information about slit Scan cameras and photography over at Prof. Davidhazy’s personal page at RIT. The basic concept for Claudio’s build was to advance all film from the film canister into to the take-up spool before exposing it and then using the camera’s bulb mode setting, rewind function and an external motor move the film slowly back into the cartridge, passing exposed film across a modified film gate that had a slit instead of a rectangular shutter.

This camera functioned in many ways:

  • As a photo-finish camera recording movement of subjects.
  • As a moving camera recording static subjects to create a strip image.
  • As a panoramic photography camera (by turning the camera) or,
  • As a peripheral imaging device by moving the subject (taking a 360 or greater “panorama” of a rotating subject).

Some of Claudio’s photography with his camera follows:

How this rig ended up with me

Claudio and I met some 20 years later when, at the beginning of 2016, he posted a picture (article top) of him using this contraption at a carnival parade. I asked a couple of questions and right then, he knew I knew what exactly he had built and why?

On the same day, we exchanged a few messages and he offered me the remains of his camera. The Nikon FA was gone and at first, I didn’t quite understand the electronics that he had made. Claudio’s design included multiple cable releases to control each part of the scheme.

It still had the high torque motor, gearbox and timing belts. The gearbox was mounted in a such a way that it had a thumbscrew to control the tension on the timing belt that linked to the rewind crank on the camera. I accepted the challenge of getting it working again and designated a broken Nikon FE I had bought in Japan for 350 Yen to be its eye.

Claudio even gave me some exposed and fully developed x-ray film to be cut and used to form the actual slit, which I did using epoxy glue to hold in place inside the camera at the gate.

The Nikon FE, although a bit smaller than the FA, fit well in the rig. I even found a Yashica finder to replace the Linhof one but later on, using a video fluid head for my shots made the viewfinder unnecessary.

I took apart the FE’s rewind crank and added a nylon gear that went on top with two tiny screws from the bottom going up. Then I made some tests using batteries to see the speeds the motor could do.

The idea was to use a slower speed than Claudio and lower ISO film as well, he was more interested in action shots and I was more interested in the movements of the city around me.

This Nikon FE like most broken FEs, simply loses the ability to time its shutter over time. It was still good for M90 and B modes though – “M90” or “Mechanical 90” refers to a mechanically controlled shutter speed of 1/90 sec.

I used a simple ohm tester to check the B setting would short the PC-Sync during the entire time the shutter was opened. That was gold, I could replace his entire circuit with one relay! I went downtown São Paulo, to a street called Santa Efigênia were you can find all the electronics shops and bought one, also a switch and some battery cases.

My tests showed that 6 rechargeable AAs could drive the motor at a nice speed. With this setup I could get some images of buses and cars passing by my studio’s window. Claudio gave me two gears for the rewind crank. At first I tried the white one, wider and made film move slower, but it had some defects and its images were jumpy. Later I changed to the black one and fewer batteries, so only 4 alkaline AAs were better for this gear.

I desoldered the wires he had used and removed his switches and some small aluminum parts he had to hold his cable releases. I had some L-shaped aluminum profile and I used that to create a “bottom shelf” for my batteries and the relay plus switch. I attached a tripod socket to the bottom of the shelf. I made all necessary connections and with lots of hot melt glue I kept everything in its place. It was ready.

The camera’s basic operation is as follows:

  • Turn off switch
  • Release tension and remove timing belt
  • Remove rewind button presser
  • Open camera and insert film
  • Place lens cap, shutter at M90
  • Advance and fire camera until end of roll
  • Place timing belt and apply some tension
  • Install rewind button presser
  • Remove lens cap
  • Change shutter to B
  • Turn on switch
  • Capture

The camera is ready to capture an image when the shutter button is pressed it will open the shutter (in Bulb mode) and the motor will rewind the film slowly into its cartridge, the film will be exposed to light while passing behind the slit, thus forming the image.

Then it is all about what moves and how. To compose the image you have to place the area that you want “scanned” vertically at the center of the frame with the camera in a horizontal position.

Looking at São Paulo through a slit

My intentions were to photograph on the streets in São Paulo, so I fitted a quick release plate under the camera to hook it up to a Manfrotto 700RC2 video fluid head, this is a very inexpensive head that isn’t fluid enough for video, but it worked ok for this project and it didn’t add to much weight to my kit. As for lenses I took both of my series E Nikons, 36-72mm and 70-150mm, my reasoning was that zoom would be more versatile.

In March of 2016, for my first shots I chose an important avenue in São Paulo, filled with people in a hurry, with my camera and tripod it was hard not to be in somebody’s way. I also chose a black-and-white film that was pretty old, an open can I got at some point, and my tests showed it had some or lots of fungus. An interesting noise to fit on top of a story about these people in a trance going somewhere.

Using the fluid head I tried many different movements to record the landscape as well as the moving people and cars. For some images I just left the camera quiet and let things move past its lenses. I gave up the cable release and went straight for the release button on the camera body, it seemed more practical.

The camera will work for as long as the shutter button is pressed. It will capture until all the prewound film is back in the canister, but there is no indication of when this happens, so it is a bit of a guess when to open and change film. By the way, film goes fast, about 8 or 9 images of 3 to 4 seconds is what I could get from a 36-exposure roll. Timing the length of the images is the only way to get a certain frame size. I didn’t do it, so my frames for this day were all over the place, there were images that spanned half a roll, some had 5cm or 6cm on a total of 17 rolls. My plan was to sort that out later.

In order to edit these images, I made a small card with a 24x48mm hole in it and started looking at negatives on a light table. I was searching for areas in the film that had interesting situations that would work ok in this format, for now. I cut the film as little as possible.

To fit these negatives in my Durst Laborator for printing, I also cut two pieces of thick museum board to make negative masks for this format, one with a 24x48mm window and the other with a slightly larger window. The outer edges of these masks were bevelled to fit my negative carrier and I was set to print. I had some Polycontrast Rapid F from the eighties, double weight fibre-based paper, it had some textured fogging all over and that noise added another layer to the images, on top of the fungus ramifications.

To print these images I used #5 contrast filter, a bit of paper over exposure and a short development (1 minute) in regular 1:2 Dektol. Cutting short was to try and tame some of the excessive fog and have just a tiny bit to give the paper some character.

I was very pleased with the deep blacks and the nice grain rendered by HC-110, finding film in this state was very lucky and I can only hope it happens again.

~ Gui

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Guilherme Maranhão
Guilherme Maranhão
Guilherme Maranhão, artist. Published Travessia book, author of Refotografia blog. Colaborates with FotoPlusTV. Currently living in Braga, Portugal.


  1. This is fascinating; might have to build a manually-operated version using an old RF or SLR body. By the way, there’s a famous movie scene shot with a cinema slit-scan camera: The conclusion of “2001, A Space Odyssey”. Douglas Trumbull was the cinematographer who designed the camera rig and executed the shots. Learn about it here: Thanks for this article!

  2. By accident, I got a 70mm film Linhof (Graflex) slit scan back .. I think of trying it out first with a battery powered drill/screwdriver : high torque, adjustable speed and ready to go. I might try to make a 35mm film version too ..

  3. hola. Muy interesante el artículo. Me devolvió a mis años de trabajo en un laboratorio fotográfico comercial donde conocí ésta técnica de la mano de un fotógrafo de carreras de caballos que usaba ésta tecnica para fotografiar la linea de llegada y despejar las dudas sobre que caballo llegó primero. Saludos desde Argentina.

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