Hey guys and gals! If you’re reading this, it’s because you want to learn how to take that noisy night photo and make it a cleaner, brighter, and better one using the photo stacking technique.
Why Stacking for Night Photography?
The technique covered in this article is called stacking, not for focus or perspective, but for noise. Digital noise is generated by pushing the cameras sensitivity to light higher and higher. This increased noise is random so, put simply, this technique adds up a bunch of noisy photos and averages them out to create a much cleaner photo.
The main reason you may want to try this is if you’re printing because noisy photos do not print well. Also, night photos usually print 1-1/2-2 stops darker than they appear on your screen or histogram. To adjust for this, you must push the ISO to gain exposure which increases the noise even more.
Stacking helps in many ways if you’re willing to put in a little extra work. I promise… it’ll be worth it!
Before we start, the following are some things you’ll need…
- Intervalometer, or cable release
- Sturdy tripod
- A small LED panel or lantern if you want to get creative with lighting your landscape
The technique must start in the field. Take between 10-15 consecutive frames with exposure settings that are right for the sky. For example, f/2.8 and 15-20 seconds at ISO 10,000 (I know it seems high but this ISO allows you to lower your shutter speed for sharper stars). The goal is to use a low shutter speed and get the sharpest stars possible… with consecutive exposures with no gaps in between. Otherwise, stacking is more difficult when trying to align all of the frames (remember the earth is always rotating). Ensure that any in-camera high ISO noise reduction or long exposure noise reduction is turned off. While you’re at it, make sure any vibration reduction or image stabilization is also off; you don’t want the lens trying to steady itself while on a tripod or it can actually have an inverse effect.
You’ll also be exposing for the shadows in your landscape, if you can, so if you’re using any artificial lighting, play with that to avoid over-exposing or causing hot spots on the landscape of your photo. An alternative is to take a second set of exposures at a longer shutter speed specifically for the landscape and blend it in.
For the next step, set your focus. Depending on how far you are from anything in the foreground, you can usually focus on infinity. I usually use a bright star in live view, zoomed in 10x or more, and rack focus back and forth until my stars are as round as possible. Or use a hyperlocal distance chart like the really handy one offered on Photopills.
Once you’ve done all of this… found your composition and focus, set your camera settings, and locked your camera down solid… you’re ready to take photos. Lock that shutter button and take between 10-15 frames (or more for better results) but I suggest starting here. The more frames you have, the more confused you might get… and your computer might explode!
When you’re back home in your laboratory, import your photos to your computer. Make your basic adjustments to your Milky Way and landscape. If you’re in Adobe Lightroom, make sure you turn sharpening off, but leaving color noise reduction on. This makes the finished stacked image look better. Once you’ve done all this, export the files as Tiffs, with no re-sizing or sharpening, to a location you’ll remember; you’ll need them in a few minutes.
Post Processing Technique
Effective stacking of the night sky doesn’t require a third party software but it really helps when trying to align, stretch, skew, and rotate frames to account for wide angle distortion and earths rotation.
If you’re on a Mac, I highly suggest Starry Landscape Stacker. It can be purchased in the App store. I have been using this software faithfully for more than three years and have created hundreds of print worthy images like the one below.
For you PC users, you have a few choices but the most convenient (and free) is “Sequator” (A great tutorial from my friend Mike is available here: Sequator – FREE PC Milky Way Stacking software that reduces noise)
In any case, take the time to thoroughly and precisely mask the sky from the foreground as outlined in the tutorials. Your finished product will be all the better for it. This technique takes a little practice and you may find you’re happy with a single frame from the set and don’t want to go through stacking. That’s ok! Its all about what you want out of your photos. Being out there under the stars is special no matter what.
Here are a few examples of stacked images as well as stacked and blended images with landscapes taken at brighter settings.