We constantly hear about people tracking and stacking to create Milky Way photos. Is it okay to take photos of the Milky Way using a single exposure?
I’ll briefly cover three ways we can photograph the Milky Way. Then, we’ll see if the last way, a simple single exposure, might be a good choice.
Tracking
Above: All photos by Tim Little, using a Pentax K-1 with Astrotracer.
Tracking is an outstanding way of photographing the Milky Way. This involves using a star tracker, which rotates your camera in the opposite direction of Earth’s rotation. Or to put it another way, it rotates the camera to follow the movement of the stars. Those of us who have Pentax K-1s don’t need a star tracker because it has an Astrotracer feature, which simply moves the sensor instead of requiring a separate tracker.
Tracking enables the night photographer to take longer exposures than a single exposure without star trails. This in turn can allow you to use a lower ISO (less noise!) while capturing more details and overall “structure” as you could from a single exposure.
If you’re including the foreground in your composition, as many of us do, then you would need to take a separate photo for that, then blend them together.
Stacking
Stacking reduces noise while increasing “signal” (the stars!). The idea here is to take several photos — one right after another — to reduce digital noise that generally occurs when pushing the camera’s sensitivity higher and higher. Then we throw the images into an app such as Starry Landscape Stacker (Mac) or Sequator (PC). The app will perform its mathematics magic to make life easy for you. It will identify the stars on each of your images, align them and then stack them.
Using this method, you might also want to take a low-ISO photo of the foreground and blend it.
Single exposure
A single exposure is, well, exactly that. You open your shutter. Then you close your shutter. Nothing more.
You open the shutter for a long exposure to gather enough of that dim starlight to register on the sensor. There’s no tracking with its subsequent blending of the foreground (unless, of course, you are doing deep-sky astrophotography, in which case there’s no foreground to blend). And there’s no stacking of multiple exposures.
So why would we want to do single exposures?
It’s easy. And there’s a certain purity and beauty to nailing an image in a single exposure, and moving on to the next photo 20 seconds later.
More time photographing. Less gear, less fiddling, and far less waiting.
There’s also far less fiddling with post-processing. With both stacking and tracking, you ideally would take a low-ISO (in other words, low-noise) image of the foreground and blend it with your stacked or tracked sky image.
Other benefits of single exposures
Single exposures were often a bit noisy, say, 10 years ago or so. But technology has advanced quite a bit. Cameras are less noisy. And software denoises far more effectively.
Because of this, in my opinion, stacking has become less beneficial than before. Even just a few years ago, the noise reduction you got from stacking was substantial. However, with how amazing Lightroom Denoise AI or Topaz Photo AI is now, noise is far less of a factor than before.
You can even reprocess your older single exposure Milky Way photos with new software technology for less noise and greater results.
Don’t get me wrong. There’s still benefits to stacking. You still get a little more detail in the stars.
And obviously, there’s great benefit to tracking. You can’t even come close to the amount of detail, color accuracy, or “structure” with stacking or single exposures. Although you cannot see most of this detail, color, and overall “structure” with your eyes at night, for some night photographers, it’s important for them to capture this for their photographs. And why not? Although we can’t see most of it, if not over-processed, the resulting image can be spectacular.
But there’s still something magical about nailing a great-looking photo in 20 seconds.
