[Best_Wordpress_Gallery id=”8″ gal_title=”Night Sky Photography Images”]
As many regular readers know (since all two of you are friends anyway), we go home for the holidays to east Tennessee, where my parents live on a small farm. There’s not a great deal of that farm that’s still in use, but there are bees and some small-scale crops, and, importantly, quiet. It’s a great place to shoot night sky photography because of the minimal light pollution, the buildings on the property and the property’s location near the McGhee-Tyson airport.
I will say this now: I’m not particularly enthralled with this image. But, I understand what I need to improve it next time, and I think efforts to improve the image were pretty successful, even though the original wasn’t what I wanted. As a blog that’s largely aimed at beginner photographers, I wanted to profile the mistakes I made and what I’ll do to correct them in the future.
The end image is a collection of unfocused natural objects placed against a nighttime sky with light trails that look like shooting stars, but are from a passing airplane in the night sky. Haunting and somewhat dream-like, the silhouetted trees and structure (the wood shed, in Stovall family parlance…) provide the subject for the foreground, and the light trail of the turning airliner gives it something of an other-wordly quality.
This image was captured after an hour of shooting in the other direction and failing to get a balance between the night sky and the crescent moon. Using a tripod and remote shutter, I was doing long exposures and attempting to get saturated star-scapes. It was too dark for the autofocus to work, and so I would fire a short shot at a very high ISO and then check the preview for framing and focus. I’d then switch back down to a low ISO and pop the aperture into the range of 6.3 to 11, and attempt the shot. I was regularly frustrated because the really long exposures that were required, 3 minutes to 20 minutes, were not coming out in focus.
It was quite cold, and when you’re standing still for 5 or 8 minutes at a time to avoid camera shake, you’re not generating a whole lot of heat, so I gave up after a bit more than an hour and went to work with what I had. The image you see has heavy noise reduction, some sharpening and then surface blur applied, as well as some color manipulation to make it cooler than it was originally. Normally, I wouldn’t apply this much post-processing, but I made the decision to not stay a true to life as normal and create more of an art shot.
- Bring gloves. And a thicker jacket.
- Going long exposure wasn’t actually my best move here. The Rule of 600 says to divide 600 by your focal length to get the maximum number of seconds you can have the shutter open before the stars’ movement becomes unacceptable. Based on this, I actually should have kept my exposure under 30 seconds; the blurring I was getting isn’t camera shake, it’s the stars moving.
- I was trying for long exposure to get saturated colors and staying in the “sweet spot” of the of the aperture range to keep things sharp, and using my 18-55mm to get a wide angle. These priorities were all sorts of warped for night sky photography. I should’ve been shooting my 55mm 1.8 at a medium-to-high ISO to minimize all the moving variables—like, the earth itself.
- Usually, I’m prepared with something to help the camera’s autofocus, but I didn’t have a laser or powerful enough flashlight, so I forced into something of a guessing game.
- I’ve never used the dark frame subtraction technique, and I should’ve planned to at least try it, but I didn’t take a dark frame while I was out. I can probably still recreate the settings and try it, but I don’t know if temp affects that sort of thing.
Unfortunately, this was our last evening at the farm before we had to leave, and it had been our first with a clear sky (though clouds don’t preclude night sky photography in and of themselves; it was the rain that did that). Next time we’re there, I’ll set up in the same place, use a much faster lens with a wide open aperture and mid-to-high ISO, bring something to help the camera’s autofocus (or at least make it bright enough so that I can confidently manually focus), set myself up to give the dark frame subtraction method a try and wear more weather-appropriate clothing.
Next time I want to experiment with long exposures, I’ll reduce the variables that could cause blur…unless, of course, it’s blue is desired.
I’ll profile both of those images once I’ve gotten them. This night sky photography image is available on Etsy.
Hey, just for a piece of information related to Dark frame subtraction. It is dependent on the temperature conditions.
One of the tricks is to just shoot it just before or just after the light frame.
Modern DSLR cameras do it automatically when you have the high ISO setting on.
Thanks, Darryl! I appreciate the info–I had actually wondered about the temperature aspect.
I have another night photography post coming up on Sunday (editing it now). You’ll notice there’s little mention of dark frame subtraction. I had the impression that it was essentially the same thing has my “Long Exp. Noise Reduction” setting, and I wanted to focus on a few other things.
Next night session, I am going to try it, just so I can go through the process and compare the results of the process with the results of the camera’s built-in functionality.
Jefferson, the only time I tend to do separate “dark frame subtraction” is when I’m doing a deep space object with my telescope setup.
They reduce the amount of noise significantly and are considered essential to a deep space shooter. I rarely use the technique with landscape astrophotography.
Ian Norman (Lonely Speck Guy) is a great shooter. He’s a great source of info.
Thanks, Darryl, the insight is really good to have.
Enjoyed a bunch of your articles over the weekend. Prepping for another round of night photos in about two weeks. I’ll be referring back to your site a good bit more!