Behind the Shot: Orion Nebula (M42)

Over the past few months I have been really looking into astrophotography. There were two celestial objects in particular that I was interested in, M42 (The Orion Nebula) and M31 (The Andromeda Galaxy).

There are many things that have to line up perfectly for a photo shoot to be even considered. The most important thing is that the object to be in your view. Believe it or not but there are many celestial objects that are not visible for parts of the year due to the movement and rotation of the earth. Using a planetarium software (Stellarium), I was able to confirm that both of the objects that I had wanted to take pictures would be in view. M42 was about 30 degrees above the horizon and M31 was only about 15 degrees above the horizon and both would be decreasing at a pretty fast rate. The nice thing is that I was going to be shooting right at sunset to get the most time to photograph before the objects fell below the horizon. This would give me light to set up and be able to see my equipment and I wouldn’t be up very late. Since I would have more time to photograph M42, I choose to give it a shot.

Another important aspect of astrophotography is good weather. If there are any sort of clouds in the atmosphere, the photos can turn out all hazy and there will be less color. Since weather is always changing, I had to keep a close eye but when spring break started, I saw that the first few days were going to be mostly clear. The time frame for my photo shoot was from 8-10 pm and so it was going to be hard to fit in a specific time frame with the clouds. But luckily one of the days, there was a perfect opening in the clouds for me to shoot.

I drove down the road to the nearest field that gave me the most tree clearance in the SW direction. Parking, I unloaded all of my gear on the side of the road. The first thing was to set up the star tracker. Believe it or not, but you can only take a picture with an exposure for about 30 sec without seeing visible star movement. Since I was zooming in and using a longer exposure to capture the nebula, I was going to need something to move my camera along with the stars. As simple of a concept that it may sound, it is actually really hard to accomplish. The star tracker has a little peep hole and you have to look through it to find the North Star and “Polar align” the tracker. Once aligned, it uses a stepper motor that rotates at about the same rate as the earth does. Once aligned I was ready to put the camera on the tracker and position it in the right direction. M42 was easy to find because it was right beneath Orion’s belt and after my eyes had adjusted to the night sky I was able to point my camera in the right direction. After many test shots, the nebula was close to the center of the photograph.

The hardest part about the photography side of astrophotography is focusing. Even though it may seem logical to set you focus ring to infinity because the stars are light years away, it doesn’t quite work like that. You can try and use the live view feature on your camera and zoom in on a bright star and try and focus it that way but using your hand doesn’t produce accurate enough results for the precise focus need to take pictures of the stars. Luckily, you can connect your camera to your computer and focus it that way through the manufacture software. It is a really long process but by focusing through the computer, the focus is a lot more precise and through trial and error, the correct focus can be obtained.

The first few photos were really blurry but soon the nebula started to come into focus. The cool thing about taking photos of the night sky is being able to capture very faint celestial objects that our eyes can’t see. Looking at where M42 should be, our eyes don’t see much but when photographed, much greater detail can be extracted from the same region of the sky we were looking at. When the first clear image of the nebula showed up on my computer screen, I couldn’t believe that I had gotten a picture of what I was after.

One aspect about astrophotography that I often forget about that can wreck a photo shoot is the dew point. The dew point is the temperature at which the water vapor in the air condenses. I am sure you can see where this is going but what ended up happening was that water started to condense on the end of the camera lens producing non usable pictures. I had not checked into what the dew point was since I had many other things to plan for and after about 15 min of actual shooting of M42, my lens started to collect water. Since the dew point was very close to the freezing point, my lens ended up freezing over shortly after taking photos the nebula. When the lens froze over, I had only gotten a handful of pictures and was nowhere near having as many photos as I had wanted.

Now that I had a few usable photos, I had to process them and make them look better. A common technique for astrophotographers is staking. To capture faint objects in the night sky, multiple exposures are taken and then combined to achieve a better result than say one individual picture. Many of the better photos of celestial objects have multiple hours of exposure time. So only getting a few pictures was not ideal for stacking but I was really happy to get some pictures in the first place. On the side of the road, I ran a few of the pictures through my stacking program while another exposure was being taken. After the 5 minute process was over, I saved the odd looking result and brought it into Photoshop to do some magic. After a few adjustments the result was looking a lot better and more like the Orion Nebula. The next day I brought the stacked image into Lightroom which was much better at making the changes to the photo I needed like pulling out all of the detail in the faint parts of the nebula and darkening the sky around it.

Looking back at the photo shoot, there are a bunch of things I would change and do better but I am still really happy with my first attempt of the Orion Nebula and I can’t wait to get another opportunity to do it again.

Shooting Data

Canon 60D

Canon 55-250mm at 250mm

f 5.6

ISO 2000

6-30 second photos

Processed in Adobe Lightroom and Deep Sky Stacker
EOS Utility software

Polarie Star Tracker