This article was written by user salvinod.

This writeup aims to describe how the above clip was made. These clips can be made with Open Source software and almost any digital camera.

Overview

A time lapse clip like this is made of individual photos snapped at a fixed interval varieng from several second to several minutes of hours then assembled together at a normal frame reate for video of between 25 and 30 frames per second. Therefore makeing such a clip requieres two steps. First you need a way of automatically taking photos at fixed intervals. Secondly you need to assemble these pictures into a video clip. The Second steps typically includes some post proccessing of the images. Cropping them and resizeing them to an aspect ratio for videos is usually nessecary, but filtering the images to improove quality can also be done.

Setting up a computer as an Intervalometer

An Intervalometer is a specialised bit of equipment that lets you snap photos with your proffesional camera at regular intervals. This is typically an expensive bit of equipment, but any computer with a USB port and a great little piece of open source software, gPhoto2 can be used as an inervalometer. The added advantage of using a PC is that you can store the images straight of the Hard Disk, so you do not need a large card, or you can make very long clips.

The obvious disadvantage is that you need to set-up your camera close to your PC. USB specifies a maximum cable length of 5m, but I could not get my camera to communicate reliably with my pc over an el-cheapo cable from ebay over 5m (my mouse, which is a slow speed device did work, how’s that for freedom?). To get around this I again resorted to the power of Open Source. Because linux can be configured to run on very low spec hardware I used an old laptop that no body could use as my intervalometer+Image store.

In order to use a laptop as an intervalometer you need to have at least a basic linux setup and the gPhoto2 software. It is best to use a recent version of gPhoto2 (I’m using 2.4.0) as support for new cameras is added on a regular bases. I chose to install Debian testing (lenny), as Debian has a very good net install facility and allows you to set up as little software as you need. Choosing lenny gave me a recent enogh version of gPhoto2 as a package. To get my PIII Laptop with 56Mb of ram running linux I downloaded the Net Install Floppy and istalled a basic sytem on the laptop. Next using apt-get I installed gPhoto2 and a few extra bits.I installed the X window System, but to keep things light I am using the FluxBox window manager. The reason I wnated X was to be able to preview the images while snapping away, and be able to have a shell along side the image. To view images I am using feh which seems to be the lightest image viewer available.

This would be a good time to lern how to use gPhoto2, particularly its remote control capability. I won’t give any short cuts, just RTFM 🙂

Setting up your Camera

This part depends a lot on your hardware and target. I am using a Nikon D50 DSLR, but any camera that gPhoto2 can remote contorl can be used. Having a better camera means that you can post process your images at will. While the difference might not seem great at low resolution, by using a High MegaPixel camera you could even produce HDTV quality clips. Also, if you want to end up with a clip with a NTSC or PAL aspect ration you cannot use the entire frame.

The most important part of the setup is using a tripod. This is a Must. The camera needs to stay put pointing at exactly the same spot. If you do not have a good tripod, you can try using a tabletop tripod, but it will be very difficult to work without one. Next is lighting. I used a flash with a fresh charge on the battries, but this might not be suitable for very long periods. In any case you should make sure that you have good bight light on your subject. To get clearer pictures choose a low aparture and low ISO setting (sharper images) and rely on your lighting. Remember the subject is not going anywhere, so high speed is not needed.

Now prepare your set up and take a few test shots to make sure your subject is well framed and illuminated. I used the camera’s own LCD display at this stage, and shot photos of the Empty Glass. Once happy I did not move the glass, but put the ice cubes in it while in place.

A few more setting to keep in mind are: Set your camera-PC link to PTP mode. This is nessecary for gPhoto2 to remote control your camera. Switch off your camera’s beep. Hearing a regular beep for several hours can be very unnerving to for those around you. I found I had to disable my flash’es sleep mode, as otherwise by the time of the next photo the flash would not be ready to trigger. Once you are happy with your shot turn off the auto-focus of you camra if possible. With subjects like glass, or ones that move slightly, the camera might have difficulty autofcusing on some shots. This can inturrupt your sequence. By using a low aperture, a slight varition in postion will still be sharp enough, at a fixed focus.

Using gPhoto2

Now attach the USB cable from you camera to your compuer and fire up a terminal and type:

gphoto2 --auto-detect

You should see that your camera has been detected.

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