Making a Lunar Imager out of a $20 Web Cam

One of the joys of astronomy for me is the interplay between technology, science, creativity, and a fascination with the universe itself. From the beginning astronomers (amateur and professional) have been masters at make-do. You have an idea, well, then try it out? No equipment? Make something!

There’s been a revolution in amateur astronomy in the past decade because of a new use for something never intended for that use. I have come back into astronomy as a passionate hobby via my other big interest, photography, and especially landscape photography. One of the drivers in photography is image size, and so cameras like the Nikon D800 with a 36 megapixel sensor, or its sister the D600 with a 24 megapixel sensor, or the similarly amazing Canons, seem to the wave of the future. RIght?

Not so fast. There are limitations to “big sensor” imagers, and they really show up in astrophotography. For one thing they are expensive. For another, they miss the fact that for many kinds of astrophotography – especially photos of bright objects like the moon and planets – very large sensor arrays are at a disadvantage because much of the detail being photographed only covers a few hundred pixels. A response? Bust up a cheap web cam.

Some very inventive people have found that not only can you make a working astronomy imager out of a web cam, but if you use it the right way and record a lot of individual frames with it – as an AVI movie, for example – you can then use software on your computer later to select the best individual fames and “stack” them – aligning and combining them to reveal details that were essentially spread out across the images, mostly by the movement of the air.

Web cams are small digital cameras designed to run off most computers, especially laptops. They are light, flexible, and inexpensive. Over the past three or four years I kept hearing that people were using web cams to take great photos of the planets and the moon. I wondered how, and decided to give it a try. This blog entry records my first attempt at such a “hack.”

One of my favourite stores is “Tiger Direct,” a big computer retailer in Ontario. I bought a 640×480 pixel web cam at the Burlington store for $19.99 plus HST, and proceeded immediately to break it, on purpose! The reading I had done about web cams for astronomy indicated that all that was needed was to get the sensor of the web cam to the prime focus of the telescope – exactly the same process as using a dSLR on a telescope, but via some creative improv. Some web cam gurus actually have created telescope adaptors that screw into a web cam and replace it’s original lens, which certainly would be a great way to do it. I figured that I’d try first with electrician’s tape.

After opening the package I saw that this particular web cam had a plastic plate around the lens, which could be rotated to focus the camera. So, using a little dumb bruit force, I turned the plate until it came off! A few more turns and the lens came off too. Here’s what the web cam looked like without its proper front end:

Front of web cam opened up

A 640×480 pixel webcam with the front plate and lens assembly removed. I also cut off a small bracket that would allow this model to sit on a desk or other horizontal surface. The lens was attached by being screwed into the small black barrel visible inside, mounted on the circuit board.

2 sensor board

The “business end” of the web cam. The sensor is the rectangle roughly in the middle of the image, mounted on a dark blue support and attached to the circuit board. The larger black circular structure is the support for the now-removed lens.

Once the front plate was off, I could see the sensor and was very careful not to damage it in any way. Camera sensors are prone to picking up dust, so I gave it a squirt of air from a camera cleaning bulb, but otherwise let it be. I then lined up a 1.25 inch T-adaptor I had in my astronomy parts box. This is just a hollow tube that can fit in a telescope where the eyepiece would normally go. At the “back end” is a broad flange with threads so that it can be attached in turn to a camera adaptor. I wasn’t to interested in the threads – I just wanted a stable base to tape my web cam to. So , I did.

3 assembly

All that was required to make an astrophotography-capable web cam was attaching a 1.25 inch adaptor to the web cam, once the original lens was removed. Here’s a spare T-adaptor about to be attached to the web cam with tape.

4 final taped 600px

The assembled imager wasn’t exactly elegant. I held the web cam against the T-adaptor with tape, making sure to get the two surface to match up as flat as possible, and that no light could come in from the sides. The silvery 1.25 inch barrel at the left was put into a telescope in place of an eyepiece.

Once taped up, of course, the big question was “would it work?” There was only one way to find out. On the night of Friday, 16 August 2013 the moon was a nice sight over Dundas, Ontario, from my west-facing apartment balcony. I set up my Meade 125TB Maksutov-Cassegrain telescope on an EQ6Pro Synscan mount. These are two fairly sophisticated pieces of kit, admittedly. The Meade telescope has a focal length of 1,900 mm and has been a favourite of mine for lunar as well as solar observing and photography. The mount is very heavy-duty, rugged, and accurate – overkill, really, for this telescope, but in a lot of important ways, the mount makes the system. As I set this all up on my apartment balcony I also had another strike against me. I don’t have a view of Polaris from the only place I can set up the mount. So, all I can do is set up an approximate polar alignment, sight a few stars for Synscan to attempt to refine the alignment, and go for it!

So, once I had a telescope set up and trained on the moon, I slipped my Frankencam into the eyepiece holder and held my breath as I focused in, using my laptop screen to see the image coming off of the camera. And there it was. The surface of the moon, in amazing detail:

plato

A portion of the northeast area of the moon, photographed 16 August 2013 at about midnight, from an apartment balcony in Dundas, Ontario, with a $20 web cam (mounted on a somewhat more expensive telescope). Visible in the middle of the image is the crater Plato. To its left is Mare Imbrium (the Sea of Showers) and to its right (north) is Mare Frigoris (Sea of Cold). This is a single fame captured by the web cam, without subsequent processing other than a slight adjustment for contrast and brightness.

I was pretty excited to see the detail coming from this little camera. At just 640×480 pixels it’s a small imager, but it can produce very interesting results.

I have not yet started any serious attempts to use this to produce “stacked” images, but I’ll try that next. There is a free program called RegiStax that has been written specifically to process AVI video files and BMP individual frames of astronomical subjects recorded with web cams. I recorded some AVI video that night, and will to have a go at processing it with RegiStax some time soon. I’m a little skeptical at the moment, however, because of what appears to be a lot of “seeing” – air movement causing ripples in the images. We’ll just have to see how that turns out! For now, I’m quite pleased with this little web cam and what it can do.

southern highlands

A region of the moon’s southern highlands, imaged with the web cam. This is one frame from an AVI video I shot on the night of 16 August 2013. The bottom third of the prominent crater Clavius is visible at the top centre of the frame.

Copyright © 2013 David Allan Galbraith
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