Webcam mod for astro photos

I recently started to learn about astrophotogray, and quickly found out that a common way to image the planets and moon is with a webcam. This might seem a bit strange as a webcam seems to be far from a high quality imaging device. The one I have sports only 1.3 mega pixels. The benefit of the web cam however is in it’s ability to record video. Again not so intuitive. After a 4-5 second video is recorded, you can then use a stack analysis program to import the clip and break it into it’s constituent frames. The most popular is registax, but as I’m a macfag I can’t use it. Instead I found Keith’s Astro Imager (for recording the clip) and Keith’s Image Stacker (for the stacking). Both are really quite handy, and extremely nerdy to use. I like them. I like Keith’s approach to software development, which requires you not to be a lazy shit.

Anyways, I dug out my old webcam, from the pre-built-in era, and cracked it open. It’s a Terracam X2 by Terratec. It looked like this originally.

 

 

I was lucky that the camera was pretty well built, using screws to seal the enclosure instead of those crappy plastic tabs that you have to break to open. This is handy for resealing it after the mod. Otherwise you’d have to glue it back together, making any future fixes or changes an unnecessary pain in the ass.

So I opened it up, and this it more or less what it looked like.

Pretty nice. The sensor is a CMOS, which is not the best for astro imaging (apparently) as it has worse low-light response, but it’s what I had on hand. The sensor itself is built onto a smaller PCB which attaches to the main board by a simple socket type connector, making it easy to pop it off if needed.

The original designers built in 4 tiny surface mounted blue LEDS as an indication of power on. I tried the camera with them in place, and it made all my images look like they had just ingested enough LSD to kill Aleister Crowley. So I had to remove them. Surface mount components are pretty easy to destroy, so I just took a small awl and carefully scraped them off the board. I also removed the microphone, just for good measure. If I were a bit better with electronics, I would have also removed the amp for the mic, as I’m sure it generates extra heat. Here’s what it looked like after the scrapping and cutting.

Good thing the LEDs were not also functioning as diodes in the circuit or I might have had to add back some normal ones in their places. That would have sucked.

To get the webcam to attach to the telescope, I had to add on an eyepiece-sized tube to the front. I removed the lens that came on the cam, and started looking for something of suitable size. I found the image inverting tube that came with my scope, and decided to cannibalize it. It’s a German brand scope, and I think they have some translation issues in-house.

I unscrewed the lower part of the tube, and hack sawed off the part I didn’t need. BINGO. Using the all-powerful glue gun I stuck the tube on to the existing front component of the cam. Looked great.

The first night I tried it out, I trained the scope on a bright star and got to focusing. The focus mechanism was all the way rolled in before it started to vaguely come into focus. damn. The sensor was not able to get close enough into the scope to get the full focus range. The next morning i took the assembly apart, and sanded off the threads of  the eyepiece. I also carved out a bit of space from the camera’s front, so I could set the eyepiece closer to the sensor. We’ll see if it works tonight. Here’s the whole assembly put back together.

So you can see, I got the eyepiece tube as close as possible to the sensor’s PCB. I think it’s actually touching it a bit. Meh. Good enough for government work.

SO. You can see it’s quite easy to modify a normal webcam for use as an astrological imaging system. Once I have some images I’ll post those up. Once issue I can image that might crop up in the future is the build up of heat inside. The little cam surprisingly pumps out a good bit of heat, which will most likely lead to some noise on the sensor. If it becomes I problem, I might have to figure out some sort of cooling system.

EDIT: So this project didn’t end up working out as I had hoped. When I tried to use the cam on an object in the night sky the image would become so noisy that it would obliterate the object I was looking at. After doing some more research I found out that the sensor has to be of the CCD variety. This one is CMOS. Which apparently stands for “Crappy iMages of Outer Space”.