Wednesday, February 21, 2007

Constellation Tour

I've been having fun with my Canon 10D DSLR lately, using just a simple tripod and 28mm SLR lens (which is probably more like 40mm as it's a lens from an old 35mm camera). With this set up, one can easily take exposures of 15-30 seconds without noticeable trailing, only depending on how close to the celestial equator the target is. I rather like this sort of wide field imaging as not only is it really easy, but it also really helps you find your way around the sky during the different seasons of the year - a must when you start looking for more specific objects and comets.

The first target was good old Orion, taken from my back yard in the centre of the city - so plenty of light pollution to combat! The results were quite surprising - especially when compared to the images I took at my Dark Site ... but i'll get onto that in a minute! This was a stack of 15 second images that needed heavy gradient removal to get a flat background due to sodium light below, and near full moon glow from the left.

Compare this to an image taken from my dark site below - there's not a lot of difference, but I put that down to the full moon present when they were taken. It might have helped being 2am on a very cold night ... it's amazing how your patience can be so tested at late hours and cold temperatures!

Next up was the home of a good few Messier objects - Auriga. Whilst easily discerned with the naked eye and bright moon light, once captured and processed it becomes another story! The image has a myriad of stars that can be quite confusing at first, and was the reason I decided to place annotated images next to the originals. Personally, I find doing this helps me learn my around both constellations and the night sky itself.

Just around the corner from Auriga is the constellation of Perseus. This contains one of my favorite binocular objects in this part of the sky - MEL 20 (Cr39) - a wonderful open cluster containing a good few dozen stars. Situated in the centre-top of the main body of Perseus, it fills the view of 10x50's perfectly. It's a real jewel so be sure to check it out!

Last stop on the tour is Taurus, the Bull. With the wide field of view provided by the 10D and 28(40)mm lens, this also incorporates the famous Pleiades - M45. Again, the rich field of stars on a photograph can hide the shape on Taurus, but in this case the bright red "eye" of the bull, Aldebaran, is quite apparent.

Hopefully I've inspired you to go out and have a go with your own digital camera. All you need is to be able to manually set the exposure to as long as possible, and set the focus to infinity. If you can't do the latter, try pointing the camera towards a distant object to get it to focus. Keeping the half-depressed shutter button down, turn the camera back to the area of sky you wish to take and press down fully. Use a hat or similar to cover the lens as you press to stop capturing camera shake as you let go of the button if you don't have a timer on the camera.

Go on ... have a go :)


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