Photographing the Great Nebula in Orion

Photographing the Great Nebula in Orion

I’ve been into photography for a few years now, and recently was getting into the idea of longer exposures, and exploring the night sky. It’s been a goal of mine to get a decent telescope for a long time, as it’s impossible not to be fascinated by the scale and distance at play when you look up on a clear night. I recently managed to get one and was impressed with the performance of it after a single outing.

The scope is a Skywatcher 200p Newtonian reflector, mounted on a Meade LXD75 GOTO mount. I got it as a pretty cheap deal, and I’m super glad I did, as I’m really loving the performance so far. The advantage of the mount is that it is equatorial, so allows me to polar align, and it also has GOTO, which is quite fun to play with more than anything. It’s quite old and needs some maintenance, but altogether a good buy.

The scope in action.

I have only managed to have the scope out in the wild properly twice at this point, but I’m more than impressed with the results that it is capable of – even in the back garden. On the first night out I managed to view the Great Nebula, and the significance of the moment was huge when you realise that fuzzy puff of light is 1340 years old by the time it lands on my humble scope’s mirror. I spent an hour figuring out how to focus with my camera and managed this (initially very impressive) shot.

An untracked 2-second exposure through the scope. Enhanced with Lightroom.

Eager to improve this and after reading so much about the different techniques in astrophotography, I decided to go out and have another go. I set the scope up and managed to polar align this time, after figuring it out slowly. The scope responded by allowing me to GOTO, and I chose my new favourite Orion Nebula from the menu. After I confirmed the position with the eyepiece I quickly unscrewed the eyepiece and mounted the camera. Using a cheap intervalometer I set the camera to shoot 15s exposures every 17s and left it to do this for a while. I ended up with 34 useable exposures.

To process the image I used Deep Sky Stacker to stack, and then PixInsight to filter and stretch. I wasn’t keen on going too over the top on processing since I knew that these images were fairly middle-of-the-road compared to some of the incredible shots other people can take. After processing for some time, I started over due to the lack of flat frames in the stacking process.

Messier’s original drawing of the Orion Nebula.

To produce flat frames I tried the “white Tshirt trick”. Using some white clothing material and a photographer’s flat light, I was able to create a fairly even field to the telescope and expose 34 frames in similar conditions. As this was not done at the time of taking the light exposures, there is likely some alignment issues in these flat calibration frames. There is still some aberration in flatness, so next time I will try to produce these frames and dark frames in the same conditions. Still need to learn what bias frames are!

After re-stacking the frames, I loaded back into PixInsight. The real challenge was stretching the histogram so that I could get as much nebula detail as possible, but maintaining as black a sky as possible. After trying a few things, I eventually landed on the final image below.

The final, processed image. And my first proper astrophotography!

I learned a lot during this process. Keen to try again on another Messier object! I now see the advantage in the calibration frames, so will be sure to do this better next time, and with more light frames. I cannot wait for planet season – Jupiter is on my hit list.

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