Andrea Nicole Photography & Web Design

The Orion Nebula

Reigning over the winter night sky is one of the most recognizable constellations. And hiding within the blade of the Great Hunter’s sword is the nebula bearing the same name – a massive stellar factory, giving birth to countless new stars, and among the brightest and most easily visible nebulae in the sky.

Still swept up in the ineffable joy of finally photographing both the eclipse and Andromeda galaxy last August, my heart swelled with excitement at the prospect of capturing the light from this breathtakingly beautiful celestial sight.

I had some vacation time recently, and in truly spontaneous fashion, threw a sleeping bag in the back of my car, picked up the 600mm lens again from my trusty camera rental store, and decided to drive east until I found clear skies. With NOAA’s National Weather Service site pulled up on my phone, I drove into the night with the sunset at my back, and patchy clouds painting the sky.

As I made my way further east, I entered the cover of a menacingly thick cloud bank. “Just a little further east,” I told myself. “NOAA says it’s going to be clear.” But the cloud bank was seemingly endless, as I drove over grassy, rolling, rural hills. The further I drove, the deeper my heart sank. But my determination was unwavering.

And it paid off.

After four hours of driving, I began to see little glimpses of sky peaking through the thick cloud layer. As I approached a larger city on my route, the cloud cover became increasingly sparse, and by the time I was in the city, I found myself amidst an enormous hole in the cloud bank.

But I was in the city. Oh, the light pollution…

My determination persisted, despite. I drove around the streets on the outskirts of the city, abutting the edge of the cloud bank, searching for the darkest skies to afford me a view of the Hunter. On the light pollution map, I ended up settling in an orange region. Oy. I have never shot in such light polluted skies. I definitely had my work cut out for me.

I found a grassy field on the side of a semi-busy road and set up my equipment in the piercingly cold, dry air. My toes and fingers went numb, as I shivered in the 20-degree weather, and methodically clicked off picture after picture in half-second increments at various ISOs, and manually readjusted the altitude and azimuth positions of my camera/tripod every few minutes.

Never really knowing how many exposures I needed in order to produce an acceptable final image, I went by my usual principal of “give it your all” and shot for a total of 4 hours in the bitter cold. Afterward, I retired to a brief night of sleep, before heading back home in the morning light.

What I ended up doing

  • Camera: Canon 6D
  • Lens: Canon EF 600mm f/4L IS II USM
  • Total exposure: 5 min, 19 sec (437 light frames)
  • ISO range: 400 – 25,600
  • Aperture: f/4

Though considered an accessible target, in retrospect, I’m not sure whether Orion was easier or harder than Andromeda. It certainly required less in terms of exposure time (5 minutes versus 13), but the technical challenge was palpable, probably due to a combination of my desperate search for clear skies, topped off with a battle against epic light pollution. But in the end, light pollution can sometimes be overcome, while clouds cannot.

It was worth every bone-chilling minute.

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Photographing the Andromeda Galaxy

Clad in the light of a million stars, I’ll never forget the first time I saw it. Just a hop away from Cassiopeia, our nearest galactic neighbor lives amidst a busy summer sky, competing for attention with the magnificent core of the Milky Way. But for those who seek out its beauty, it is every bit as breathtaking.

While in possession of the 600mm Canon lens I used for the eclipse, I sought that beauty for real this time (instead of my accidental capture a few years ago while doing wide-field of the Milky Way).

Without a tracking mount, I knew I’d have my work cut out for me; but the complexity of the situation would prove no match for sheer determination. My task involved calculating the maximum exposure time I could get away with before star trails became a problem (which at a focal length of 600mm was going to be really short) and relying on: a) tracking the galaxy manually by independently adjusting the azimuth and altitude positions of the camera every few minutes, and b) taking a massive number of short exposures that I could later stack in Deep Sky Stacker to increase apparent exposure length.

Light pollution is a perennial challenge faced by the astrophotographer, its lament only exceeded by that of clouds. So I packed up my gear and set out for darker skies. Using my oft-referenced Dark Sky Finder, I ended up in a green location, which although not ideal, was the best option given the circumstances. Conditions were further worsened by a large, uncontained wildfire near the area, creating significant air pollution. But alas.

After getting all the gear set up, the first task is locating the photographic subject. Of course, there are a million ways to skin this cat. For Andromeda, I know where it is relative to the constellation of Cassiopeia, so I just located that first and then star-hopped to Andromeda. You can also try the Google Sky Maps app, with which I’ve had variable success; it can be useful if the compass on your phone is perfectly calibrated, but for me, old-school star hopping has always just worked better.

Stellarium, a free, open-source software program that I rely on heavily for planning my astrophotography outings

On a side note, if you do happen to be doing wide field, in addition to Stellarium, Google Earth can be an extraordinarily powerful tool for planning your shots, by punching in the locations you’re considering and checking them out in three dimensions, to search for the ideal foreground.

View of Prusik Peak in Google Earth

For starters, I calculated my maximum exposure time, based on the formula I laid out in my wide field astrophotography post. I am now using a full-frame camera (6D!), so the formula was:

Max exposure = 600/focal length.

So, with a 600mm lens, the calculation is pretty simple – 1 second. But I like to live dangerously with my exposure times, so I used this as a mere guideline around which to shoot.

What I actually did

  • Light frames: 823
  • ISO range: 6400 – 25600
  • Aperture: f/4
  • Exposure range: 1/4 – 2 seconds
  • Cumulative exposure: 13.5 minutes
  • Dark frames: 99
  • Bias frames: 95

I can’t recall how many actual photos I ended up taking of the galaxy, but after going through every single one individually to evaluate quality, I ended up with 823 usable light frames. I managed to push some of the exposures to 2 seconds, but notably these were extremely hit-or-miss in their usability. The aperture was f/4 for all shots, which is wide open for this lens, and there were happily no problems with coma distortion. I also took 95 bias frames and 99 dark frames to add into the stack, as this strategy can reduce noise in the final image.

Dark and bias frames

If you are doing any kind of deep space astrophotography, you need to know about dark and bias frames because they can be helpful in creating a quality final image.

Dark frames are captured by taking images with the lens cap on at the same ISO, exposure length and ambient temperature you took your light frames at. Stacking these images with your light frames essentially “cancels out” the thermal and electronic noise generated by the camera. Since I shot at so many different exposures and ISOs, I ended up with a lot of dark frames.

The purpose of the bias frames is to basically zero out all the pixels, so they all have equal starting color values. Bias frames are also captured with the lens cap on and at the same ISO and ambient temperature, but at the shortest exposure time allowed by the camera.


My initial image out of Deep Sky Stacker had a distinctive red hue, I’m assuming secondary to airglow, given that the night was moonless and I was under relatively dark skies. This is really the first time I’ve so prominently captured airglow; usually, I end up with more green tint because of the Bayer filter in DLSRs that generally captures twice as much green as red or blue, coupled with the ambient yellow-green haze from light pollution. Anyway, I popped this into Photoshop and did a variety of post-processing maneuvers, mostly using Curves, which worked nicely and produced the above final image.

My post-processing technique is usually fairly straightforward. I essentially set the white balance in the camera to “daylight”, and once I take my image from Deep Sky Stacker into Photoshop, I open curves and adjust each individual color channel by moving the lower left slider to match up with the beginning of its respective color peak on the histogram.

Beyond that, I generally make a few adjustments to the RBG Curves line to increase contrast, and occasionally do some work with Levels. I usually make a pass through a noise-reducing program. I don’t have anything specific to astrophotography; I use Topaz DeNoise, because that just happens to be the noise-reducing software I have. I think there are some programs that are better for astrophotography, but I’ve never used them.

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