Stars and Photography (follow-up)   4 comments

The Milky Way soars over the North Cascades, with the city lights of Seattle (left) and Vancouver, B.C. behind the mountains.

A short post on photographing the night sky.  I’ve discussed this before, so won’t repeat myself.  If you want some general advice on this check my post and some of the many other web resources.  For some inspiration try Wally Pacholka’s site or that for TWAN.

The above photo demonstrates a few interesting things about the subject.  I’m showing it because it illustrates not only a few good things, but at least one thing to possibly avoid.  I’m still learning a lot about this stuff so I don’t mind admitting when I mess up.  I still like the image though, primarily because it shows the following:

SCALE:  It is so hard to show scale in photographs like this.  A very common technique is to include a strong foreground element, like a strangely shaped tree, an interesting building, etc.  But this is not strictly showing scale.  The background in these images is still just assumed to be large – not exactly precise.   It is, nonetheless, a great way to “depthify” the picture.  Like that word?

In the above image I was able to show the city lights of both Seattle and Vancouver, Canada, which are 150 miles apart.  At first I thought the lights were messing with my desire to show a deep starfield, but then I realized that the lights actually helped with depth.  It happens so often when doing photography, that you are frustrated with an element you think is interfering with your composition.  The key is to take a deep breath and consider what that element is actually capable of doing for your composition.

LOCATION:  For the above image I knew I wanted to be as high up as possible.  The air was somewhat hazy because of fires, and during the day I noticed as I crossed Rainy Pass that the smoke was mostly hanging in the valleys.  So I decided to spend the night at the top of Slate Peak, which at nearly 7500 feet is about as high as you can drive in Washington.  The height helped me to shoot over the haze, and made the stars that much brighter.  On the downside the top of a mountain does not usually offer a strong foreground element.  There was a lookout tower, but I didn’t think it was interesting enough.

SIMPLE COMPOSITION: This is of course a goal for all landscape photography, but for starscapes it might be even more critical.  I mostly like to make the sky – Milky Way, comets, aurorae, etc. – the star of the show (pun intended).  And when I use a strong foreground element I want it to share the spotlight.  I want to wow people with the universe, which we don’t look at or think about very often.

And so I went with the simple composition of Milky Way arcing over the North Cascades.  I would have liked to have a better profile of the mountains, which are jagged and thus interesting in silhouette, but my viewpoint was much too high for that.  It was a tradeoff between wanting to be above most of the haze and having the mountains in silhouette.  I could have driven back down a ways after the sunset, but believe it or not I was nervous about trying to turn around at night from my precarious parking spot.  It was a long way down.

Also, a simple composition allows for a super quick and easy composite when you’re combining two shots (in this case one for the foreground and one tracking the stars so that they are sharp).

SHARPNESS:  One weakness of the shot is that the stars, while fairly sharp, are not perfectly round points.  I was using my tracking mount (a Vixen Polarie) to track the apparent movement of the stars.  This allows you to go much longer than the 20 or so seconds that you’re limited to when shooting from a regular tripod mount.  Of course you can always raise ISO, and if you have camera like the Nikon D4 or Canon 1DX, you (a) have more $ than I do, and (b) have more flexibility and might not even need to track in many cases.

The polar alignment you do for the Polarie is pretty basic.  You simply point it at the North Star, making sure it’s visible through a little hole.  Vixen sells a much more precise polar alignment scope for it, but for now I can’t justify the extra expense.  For one thing, when you use a very wide angle lens, as I usually do, the slight drift does not cause noticeable blurring of the stars.  But the longer your exposure, the better chance to get blurred or trailed stars.

I’ve already mentioned a second weakness of the shot.  It has no good foreground element, unless you count the mountains as foreground.  I happen to think the city lights add enough interest, but it certainly can be argued that this is a stronger image with a good foreground element, perhaps illuminated by “light painting” (shining a light on the subject).

EXPOSURE & PROCESSING:  I was using my Tokina 16-28mm f/2.8 on a Canon 5D Mk. II, at 16mm focal length.  I took two shots (actually three including the dark frame).  One was with the tracking mount switched off, and the other had the mount tracking the stars.  I shot both at the same exposure, but I don’t always do this, especially when there is a moon or other complicating factor.  That exposure: 133 sec. at f/2.8 (largest aperture for that lens) & ISO 200.  I shot the same with the lens cap on for the dark frame.

I processed pretty simply.  First I imported into Lightroom and worked on the image with sharp stars.  I moved the highlights and the contrast sliders pretty high, moved the blacks lower, upped the shadows and clarity a bit, and added quite a bit of  noise reduction and sharpness (with a healthy amt. of masking for sharpening).  Then I used synch. to apply the same settings to the image with a sharp foreground.  Then I opened this and zoomed in to the mountains to adjust both sharpening and noise until I had the best compromise.

Then I took both into Photoshop, made the sharp mountain shot my background, selected the stars from the other one, and copied this over.  I added a mask overlay and used a brush to clean up the horizon.  In this simple case  it only required a few long strokes along the mountain tops to reveal the underlying image’s sharp peaks.

I zoomed in and looked around the image for the tiny red or green dots that indicate hot pixels, a common effect of long exposures in darkness.  I didn’t see many, so I decided not to bother with dark frame subtraction.  If I was to print this image at a large size, I would have done it.  But for most things those hot pixels won’t show up.  That said, it’s very worthwhile to always take a shot with the lens cap on, and at the same exposure as your real shot(s).  It has to be at the same exposure as your main shot(s), and at or near the same time for the Photoshop technique of dark frame subtraction to work.  Do it right after your main shot(s).

Okay, hope you found this useful.  I always appreciate comments and questions.  I normally don’t do photography tutorials on my blog (too boring after awhile), and prefer to educate more on the subjects and locations I shoot in.  But I will do this from time to time.

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4 responses to “Stars and Photography (follow-up)

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  1. Thanks again John. You’ve inspired me to work on editing all these starscapes from my recent trip. Wonder what brought you to Brazil (what’s her name?).

  2. Have you ever ventured down to the southern hemisphere? The Milky Way is far more pronounced than in the north.

    • Thanks for the comment. I was in southern Africa last year and you’re right, mostly because of the Large and Small Magellanic Clouds. The view over northern Lake Malawi at night was truly awesome. I never did any serious astro images down there, guess I was too focused on wildlife. Love to go to Aussie and do some outback astro and landscape imaging.

      • I’m Australian (now living in Brazil) and have spent a lot of time in the scrub free from any unnatural light. Astonishing night sky. You have a real gift for astro-imaging. The shots over the lake left my jaw on the floor.

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