Stacking - The Key To Noise Reduction

Early in my nightscape photography journey I learned a technique that has been a core part of my shooting ever since. I took a series of images that I had captured as part of a timelapse and tried something I had read about called "stacking" It's a post processing technique that stacks sequential shots, aligns the stars, averages out the random noise and enhances the detail.

When the shutter of a camera is opened and the sensor is energized so that it can capture light the electricity passing through it generates heat. That heat can show up in images as random noise. For typical microsecond shutter openings this noise is virtually undetectable but those of us capturing nightscapes often have exposures of 10 seconds to several minutes. For us the noise in the images, especially the darker portions can be easily seen.

The only options to reduce the noise in your images is to use a tracker and shoot at a much lower ISO or stacking. Since trackers are expensive and more difficult to use while you move around on a dark beach stacking seems to be the answer. All you really need to do is shoot extra images.

My workflow while I'm out shooting is, capture an image to check exposure and composition then set my camera to automatically take 9 more. I have stacked a few as 3 and as many as 21 but the sweet spot seems to be 9-10. Each composition takes about 5 minutes and stacks of 10 or less don't work the computer processor so hard on the other end.

Fortunately there are several programs that will stack and align the images for you automatically. Starry Landscape Stacker for Mac and Sequator for Windows. There are a few others but these are the main 2 and those I have had experience with. I have YouTube videos on how to post-process stacks and I'll do another blog explaining the steps later.

The image below was captured in June of 2024 on Old Lighthouse Beach at Cape Hatteras and shows you the difference between single processed shot versus a series of stacked images. The finally image is a stack of 9 and the single is the first shot in the sequence processed the same way. The stacked image is much cleaner and sharper.

One of the real advantages of working with stacked images is their ability to hold up under more aggressive post processing. They can be pushed much farther to bring out more detail. It's not the answer to everything and stacking won't automatically make your shots magical but the simple act of taking 9 instead of 1 will give you a lot more options.

If you have questions about stacking or anything else related to nightscapes or need some coaching please reachout to me.

If you're interested in learning to shoot nightscapes or post processing check out my YouTube Channel here.  I'm also available for private coaching in the field or zoom sessions where we can work with your own images.