I can’t remember how it started, but my attention was caught recently by the idea of slitscans. The term seems to be used indiscriminately for different but related techniques, so I’ve tried to categorise them for my own understanding.
Firstly, there’s the creation of a sequence of images from a backlit static original. That’s how the stargate sequence for ’2001: A Space Odyssey’ was created, as well as the original Dr Who title sequence. It’s a laborious approach, where, for each frame of the sequence, the camera shutter is held open while the camera is lowered towards the static image. Only a thin line of the original is visible through a slit (hence the name), and the light coming through it falls on different parts of the film as the camera’s position alters. For subsequent frames, the camera is raised again, the film wound on, the original image moved slightly so the next part of it is visible through the slit, and the process is repeated.
Intriguingly, someone has reverse-engineered the stargate sequence to produce some of the static images that must have been used to create the effects.
The next version of the technique creates a single image from a sequence of images. A common use is to capture a series of timelapse images of a scene then take adjacent slices from each one and combine them. The result is an image of a scene where different parts of it represent different times. The teeming void has examples of a street scene and the sky.
A variation on this approach captures a single image from a changing scene by using a box with a moving slit in it in front of the camera. Alternatively, though it’s more restricted, you could move things while scanning them.
Finally there is the creation of a sequence of images from a sequence of images. This seems to be particularly popular because of the weird effects you get from simple movement. It’s a development of the previous technique, where each frame of the output sequence consists of slices of different frames in the starting sequence. You can watch a test video to compare the input and output frames and see what’s happening more clearly. Some video editing programmes provide filters to achieve this, and people have supplied code for use with Processing and Quartz Composer. It can be impressive, but the novelty value of this approach wears off very quickly.
I’ll develop this topic further in some way, but in the meantime, if you’re interested in delving deeper into the subject, there’s an extensive collection of examples assembled by Golan Levin.
This time-lapse film of a night sky starts quietly and appears to be dull, but it’s worth persevering… If you’re interested in how it was made, read the tenth comment, and scroll down further for an explanation of the AA screen.
It’s spread across the internet, and was on the front page of yesterday’s Times. What is it? It’s a photograph of the space shuttle in front of the sun. It’s a powerful and exciting image, but I find it unsettling.
The shuttle is tiny against a quadrant of the huge yellow star behind it. A filter has removed all solar flare, so the sun looks more like a planet. The optical trick played by relative sizes and distances makes the image look like countless establishing shots in science fiction films and programmes of a space craft in orbit around a planet where crew members have landed, though normally the spacecraft would appear larger.
Our familiarity with such shots means that it’s easy to misinterpret the image. The shuttle is not near the sun at all. We are not close to travelling to other planets. The headline in the Times, “Set your controls for the heart of the sun” is not meant to be a suggestion that the shuttle will travel to the sun. It refers to a track by Pink Floyd on the 1968 album, ‘A Saucerful of Secrets’, written at the time of the Apollo rockets and shortly before the first moon landing.
Perhaps all the recent discussion of space tourism, including Richard Branson’s talk of space flights for £10,000 within ten years, together with NASA’s desire to resume manned flights, contributes to an excited feeling that we are on the verge of a new era. Yet if air travel is a major cause of environmental damage, why are we even contemplating extending it with completely unnecessary leisure flights to the edge of the atmosphere?
But that feels like a curmudgeonly attitude. When I was growing up, like many others, I wanted to be an astronaut, and believed that space travel would soon be commonplace. Why should we voluntarily give up that dream, just because it might cause harm to our planet?
There is no claim that the photograph of the shuttle in front of the sun is art, but my troubled response to it makes me willing to consider it so.
For the first time in far too long, I dug out my SLR and video cameras today. It’s so long since I last used them that I had to think while setting them up, but I enjoyed today’s session – some close-up stills and timelapse filming of a slug, in preparation for more prolonged filming at work next week.