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
EOS Utility software
Polarie Star Tracker
