Focal-plane shutters and camera-phone slit scan

The principle of slitscans explained and done deliberately in the last post also applies to "ordinary cameras" under certain circumstances. In the "old days" of film photography, this meant focal plane shutters.

Focal plane shutters

Most 35mm film SLR cameras have focal plane shutters. A few compact 35mm cameras have them too (usually the ones like Leicas or Zorkis with interchangeable lenses.) Some medium format cameras have focal plane shutters, and a small number of large format cameras have them. Focal plane shutters have two moving blinds next to the film - one blind opens and the other closes. The advantage for the camera manufacturers is that the closing blind can start to close before the opening blind has finished opening. This makes the shutter look like a slit moving across the film. The slit is narrower the "faster" the shutter is. That's why the manufacturers like these shutters: they don't have to make anything actually move fast, just make the slit narrower. Of course moving slits play havoc with other aspects of photography: they are not good if you want to take pictures with flash, but they are cheaper.

The famous picture by Lartigue is an old one taken with a rather slow focal plane shutter set so the slit is rather narrow. In this picture he captures the car quite sharp (but not the wheels) but it is "slanted" as the shutter or slit is moving from top to bottom. In fact to make it more complicated, Lartigue also pans the camera in the picture, but not enough to capture the car vertically.

If you own a camera with a focal plane shutter you might experiment with it: set it to its fastest speed and take photographs of rapidliy moving objects. Helicopter blades or aeroplane propellers are good subjects. Try holding the camera the nomal way, on its side, or even upside down. Some focal plane shutters (the majority, probably) go from side to side, and some go up and down. For example my Olympus OM1 has a side-to-side movement, whereas my Praktica MTL has an up-and-down movement. (Because of the vertical shutter Prakticas of the 1970s are ideal for these experiments.) I must try this again, but unfortunately I haven't got any nice images from these cameras to show here right now.

Digital slitscans

But in the modern age, some digital cameras work as slitscans too. In this case there is no slit moving but the camera's processor is so slow and is programmed to grab the scene a line at at time, that this moving line as it is "grabbed" is similar to a slit. Try the camera attached to your phone. Or even better get a very old phone and try that. My phone is quite old, and I was pleased to get this image out of the window of a moving car.

With some panning you might get a nice artistic illusion of speed.

Try to work out which way your phone or digital camera scans. I find my images are much better if I hold my phone upside down!

Camera Mods and Hacks

Digital camera manufacturers make cameras for all kinds of photography, especially the sort that is about record-keeping, advertisement or portraying a message in as simple a way as possible. Their job is to make their cameras as perfect as possible: to make them take pictures that can be measured scientifically to be as accurate and faithful to the scene in front of them and to remove the quirks that cameras in the bad-old-days used to produce irritatingly often.

Cameras are now very good, and in particular are excellent at giving us smooth gradations of tone on an LCD computer screen. With a few tweaks in one's favourite photoshop we can all look like we live in the smooth perfect world where film actors and actresses live and no-one ever has a single hair out of place. (I prefer the Gimp by the way, but "to photoshop" is now the accepted verb for the activity of editing in even the Gimp.)

For photography for advertising (even self-advertising) or for record and photo-journalistic uses, this is exactly what we want from our cameras. But for photography for art, especially photography that aims to make an old-fashioned printed picture that goes on a wall in our house or in a gallery, the "perfect" quality of the digital camera is lacking in exactly those little features and quirks that can bring it to life.

Of course, this is nothing new. Even film cameras were being pushed towards the end of their heydays towards the perfect machines for advertising. It's just that the digital revolution has taken this a bit further.

These pages are about how to tweak a camera - any camera, digital or film - back to producing pictures that might grace a art gallery as something special in terms of its quality of tones, textures, or something else. That's not to belittle the work of photojournalists, advertising photographers, or any other kind of photography. But these web pages are about a different kind of photography where the process of taking and making a picture is slowed down to enhance the qualities of the tones and marks on the image themselves.