Webcam astrophotography

Posted on March 24, 2008 in Astrophotography. - No comments

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I’d long admired the impressive images that had been captured by amateurs using an inexpensive equipment in every more creative ways. Having had my appetite wetted by some fantastic images on the net I decided to have a go myself.

The equipment

I purchased a Philips Toucam Pro from Amazon and a screw-in webcam adaptor from Telescope House. At this point I had no plans to modify the Toucam to enable long exposure images so I knew I’d be limited to taking pictures of the moon and planets. I figured that if it worked, I could always get the camera modified later. In order to drive all this I was going to use a cheap second-hand laptop that I’d managed to obtain. It wouldn’t be fantastic, but it should do the job.

The webcam would be housed on my Meade ETX-90.

How to focus on nothing

There were more than a few things I had to learn. The first thing to try was to get something in focus! There were two significant problems that I had to deal with

The first was checking that the telescope was in-fact pointing in the correct direction (it was difficult using the finderscope with the camera located in the eye piece). This was even more difficult as the target object had to be smack bang in the middle of a very small CCD.

Once the telescope was correctly alligned, the second problem was trying to get the image in focus.

One technique that I’ve been told about is to use the moon. It’s a nice, large and bright object that is easy to focus on then once you’ve got the webcam in focus, you can then just worry about trying to point the telescope at a fainter planet. This is fine – if you’ve got the moon around to play with!

Trying to focus on the laptop’s screen was difficult because of the delay in the displayed preview image and besides, how do you know if you’ve got anything in focus when all you’re looking at is a screenfull of gray fuzz! In the end it was a best guess – moving the focus from backwards and forwards before going for something in the middle (and all the time hoping that the ETX’s tracking is going to keep the target in the screen!)

Obviously with practice this should get easier, but the added pressure of the rapidly diminishing laptop battery didn’t help either. Another thing I had failed to take into account was how the cold weather would affect the battery on the laptop.

Stacking the images

Once I’d managed to get some short 400 or so frame movie files captured it was time to try and process them and see what I had. Reviewing the individual frames proved to be rather disappointing with very very few images close to showing any detail (but I guess my expectations were a little unrealistic for a first attempt!)

The general idea now, is to process the captured frames, aligning the drifiting target and then stacking the images to amplify the image and lose the background noise. In order to do this I was using a free tool called Registax.

The amount of control and setting you’re confronted with is quite daunting, but using a guide I’d found on the internet and not trying to do anything too complicated I managed to get something a little more recognisable than the grey fuzzy blogs I’d captured. In fact the results were surprisingly good. With the “eye of faith” it was possible to see things that hadn’t been visible to my naked eye such as the colour!

The results

This is an image of Saturn that I managed to capture on Saturday, 24th January 2004. It had taken a lot of trial and error to get his far, but now I’d just about managed to get my head round some of the software controls and things were starting to look much better than the poor images captured on the previous nights. The image was made from a 400 frame movie at 640×480, stacked using Registax.

This is my first attempt to image Jupiter. It was taken on Wednesday, March 24th 2004, while on holiday in Cornwall. This is the first time we’ve tried using the 2x Barlow which made focusing interesting, and trying to get Jupiter centred was a nightmare! (We’d given up trying with Saturn!).

It was fantastic to be away from the city light pollution we get at home, but what really wasn’t helping either was the wind trying to keep Jupiter on screen long enough to do a decent capture was a real challenge and it often looked more like a UFO darting around all over the place.

Afocal astrophotography

This was our first attempt at afocal photography. It was taken by holding an Olympus C-2 at a 26mm eyepiece.

It proved to be very difficult getting the camera lined up with the eyepiece using the small display on the back, but as a first attempt I don’t think it was too bad especially given the lack of any form of bracket and the total lack of any kind of exposure control on the camera itself.

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