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Deep Sky Astrophotography with your Camera and Lens Part 1
Many people think that if you want to photograph deep space objects, you will have to acquire a heavy tracking mount, a telescope, a specialized cooled ccd camera and have very dark skies. Although those tools will give you a nice start to achieving a really high quality astrophotopraph it's not always necessary if you want to join in on this very rewarding hobby.
Recently I purchased this small "book sized" tracking unit called the iOptron Skytracker. Aside from the camera and telephoto lens, all I needed for this to work was my camera tripod and ball head. My goal with this unit was to have a very portable deep sky astrophotography setup that I can take with me when I travel or leave home.
After a relatively quick and straight forward setup, which included aligning on the north star, it was tracking and ready to go. I decided to test it out on the well known "Orion Nebula" M42. I used my Canon 6D and 100-400mm lens zoomed to 400mm. My ISO was 800 which is what I usually choose when shooting these types of images with my DSLR. It's just high enough but not too high so as to compromise colour quality or increase noise too much. My fstop was f7.1 but I meant to go with f5.6. I did a number of test exposures to see how long it could track without getting star trails and I found I was able to go not much longer than 1 minute at that focal length for that part of the sky. The shorter the focal length of the lens, the longer tracking time can be achieved. Below is what I got straight out of the camera. As you can see the stars are fairly round and the nebula shows up nicely but there is still more work to be done. Note that the brownish toned sky is a result of my light pollution.
Now in order to get more depth, detail and colour, you have to increase the signal to noise ratio by taking and stacking multiple frames. For this target I took 57 of them at 1 minute exposure length and stacked them in a free program called deep sky stacker. I also collected dark frames and flat frames. Dark frames help to reduce noise and flat frames help to correct vignetting and/or any dust motes that appear on the sensor. Finally, the most challenging but also the most rewarding part was completed in Photoshop. I will do another blog post later this month/early next showing the steps that I used to get from the single image above to the final stacked and processed image below.
READ PART 2 * Here*
Hope you like the results!
Awesome picture! I have similar camera and lens and I really want to make an experiment myself. I'm from California so the area is super light polluted! May I ask if it is possible to have "good" nebula picture? How can I know where to point my camera at? Sorry for stupid questions. I am an amateur in photography :-(
HJ Chartrand' Montreal, Quebec, Canada(non-registered)
Wow! This is impressive and inspiring for a newbie like myself. Thank you for sharing your recipes. I will continue to experiement with my own. Your will be my guiding light if I may say so.
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