Telescope cam debugging

I was reminded the other day that if you want to do planetary astrophotography, hacking up a webcam is a cheap and easy way to computerise image capture. Better still, software exists to process videof rames into a single higher quality still image.


A spot of researching which webcams are best suited for this found a page explaining how to hack a Logictech Webcam Pro 9000. Better still, my corner discount computer parts shop actually still stocks these for all of $35 a piece.

Since kattekrab uses one with Skype, I know they work fine with Linux. They're also listed as supported on the UVC driver and tools page, which is helpful as I will need software (on the laptop) focus and zoom control.

Webcam Pro 9000However, after plugging in the camera, guvcview was hating on it, refusing to start. uvcdynctrl said it could see it, but refused to talk to it saying /dev/media0 was missing. the MAKDEV script doesn't mention /dev/media devices,  but a quick google shows that it's a chacter device with major 251 and minor 0.

Just to be sure, I checked if I had one of those already, and lo and behold I did have a /dev/fw0 with those magic numbers! I assume that at some stage the 3.x kernel series switched to fwX device names, leaving the UVC utilities unable to cope.

The upshot? If you want to use the UVC utilities for image or video capture, run ln -s /dev/fw0 /dev/media0 first or, better yet, add an udev rule to create that symlink automatically when you plug in the camera.

I am now able to keep an eye on my cats in 1600×1200 at 10 fps :-)