Getting Familiar with a Webcam

If you are a complete webcam beginner, once your webcam arrives, simply follow the instructions in the box and install the supplied software. You may choose to ultimately use different software to control the camera, but you must install the proper manufacturer's drivers, as directed, to start with. In practice, you will simply be using the supplied software to record what is called an "AVI" video on the hard disk. The Philips routine that does this is called Vrecord, but it will all depend on what webcam you ordered.

If you have never used a webcam before, it is essential to spend a few days playing with it and the manufacturer's software indoors with the webcam's normal lens attached. Get to know how to use the webcam in "manual" mode before you try connecting it to the telescope, i.e., untick the "auto" box (see diagrams). In passing, it is worth mentioning that the tiny webcam lenses, supplied with commercial units, usually have a crude infrared blocking filter, in the form of a coating or a plastic strip, attached to the rear lens. Once this lens is removed, the full sensitivity of the CCD chip, which reaches much further into the infrared (and a bit further into the UV) than the human eye will be revealed. While more sensitivity to light may seem a desirable feature, it does mean that when planets are low down the color dispersion will be considerable. Thus, many amateurs purchase an inexpensive UV-IR blocking filter to screw into their webcam adaptor or Barlow lens to restrict the spectral range and give truer colors, too. But for first steps, such a filter is not necessary.

Once you have got to grips with your webcam software and know how to save an AVI video to disk, check just how much of your hard disk is disappearing. At 640 x 480 resolution, each color frame of a TOUcam video takes up almost half a megabyte. You can eat your hard disk up at a rate of 4 or 5 megabytes a second when storing AVI videos at 10 frames per second: you have been warned! A frame rate of 10 frames per second is a good one to choose. Faster frame rates tend to corrupt the finest detail due to image compression.

Alternatives to the manufacturer's webcam software exist aplenty. The webcam-friendly astro-package, called IRIS, which has a webcam viewing/recording option can be downloaded from http://www.astrosurf.com/buil/us/iris/iris.htm.

The K3CCD Tools package can also be used. K3CCDTools can be downloaded from http://www.pk3.org/Astro. This software, by Peter Katreniak, can also be used to align and stack webcam AVI frames in much the same way as Registax, although Registax is far more widely known and, in my view, a far more versatile package.

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