My goal for my landscape photos has always been to have them printed large. That’s why I try to avoid noise and through use of techniques like focus stacking and exposure blending I ensure best sharpness and detail.

When photographing around sunset and sunrise and into the blue hour, achieving the quality I’m after is no problem. As it gets darker I simply increase the shutter speed and there’s seldom the need to use high ISOs.

Milford Blues – 10s – 30s | 35mm | f/11 | ISO 100 | Focus Stacking + Exposure Blending

Night Photography

But when I want to photograph the night sky I have a problem. In order to get the stars razor sharp, the maximum exposure time I can use is limited by the focal length at which I’m shooting and by the desired print size.

Many people use the 500 rule to calculate the maximum exposure time at which the stars will still show up as points in the photo. When using a full-frame DSLR, dividing 500 by the used focal length gives the maximum exposure time in seconds. When using a crop sensor camera, you have to divide this time by the crop factor.

I never found this rule helpful though. It might be sufficient for small prints and presentation on the web. But for pixel peepers like me the resulting photos show too much trailing, especially to the edges of the frame. So before applying this rule or any rule, it’s usually a good idea to do some tests. I found that for me instead of a 500 rule it’s rather a 250 rule, if I want to print the resulting photos up to 40’’.

Single Exposure of the Night Sky over the Erg Chigaga at 15s | 16mm | f/4 |ISO 6400

This leaves me with relatively short exposure times, even when photographing at 16mm. And because I only have an f/4 lens, I have to use very high ISOs to achieve those. If I did night photography more often, it would certainly make sense to invest in a 2.8 or even wider lens. But I like to travel light and thus had to find alternatives for getting high-quality results.

Image Averaging

The good thing about image noise is that it’s random. When I take several photos of the same scene at a high ISO, the noise will look a bit different in each of those while the static features of the scene remain the same. During post-processing, it is then possible to average out the noise.

Since the stars move across the night sky this would result in even more trailing. But there are tools that allow to first align the photos for the stars and then perform the averaging.

Those are Sequator for Windows and Starry Landscape Stacker for Mac OS. Since I’m a Windows user I’ll show you what Sequator can do. But I’m sure the results in and Starry Landscape Stacker would be very similar.

During a recent trip to Morocco, I spent a few days in the desert and one morning I went out to photograph the Milky Way over the Erg Chigaga. With no clouds in the sky the conditions were perfect to apply image averaging. With my camera mounted on a tripod I took 40 consecutive photos, using a 15 second exposure at f/4, 16mm and ISO 6400.

The image below shows a comparison of the different noise levels at 100%. From left to right you see the unprocessed raw photo, the processed raw, then an averaging of 10 photos and finally the averaging of 40 photos.

1st: Canon 5DsR | 15s | 16mm | f/4 | ISO6400 out of camera
2nd: Pre-Processed in Lightroom
3rd: Averaging of 10 Photos
4th: Averaging of 40 Photos

The difference between the two photos in the middle is significant. The averaging massively decreased the noise while the stars maintained their form. The difference in quality when going from 10 to 40 photos is not that huge. But it reduced the noise even further to a level I can live with.

As with the 500 rule, the key here is to do your own tests. Find out how many photos you need to get to a result that you can live with.

Time Blending

The image averaging solved the problem of noise in the sky. But when I took the photos it was pitch dark in the desert. Even exposures of several minutes wouldn’t have revealed enough detail in the foreground – certainly not at the aperture I would have needed to get everything sharp in the frame.

A solution to this is a technique called time blending, which refers to combining photos of the same scene that are taken at different times of the day. Those can be taken minutes or even hours apart.

The Milky Way that morning was best visible around astronomical twilight. And usually the best time to photograph the landscape for such a night scene time blending is during blue hour. Then the light is still very blue and soft, which simplifies the blending.

After taking the 40 photos for the Milky Way I left the camera in place for 90 minutes. In the end, the blue hour didn’t provide the softest light that morning, so I ended up using the photo you see below for the landscape, which was taken just minutes before sunrise.

Photo for the foreground taken at 0.7s | 20mm | f/9.5 | ISO 100

Now, this photo does not look like night at all. But it contains a very important feature of a night image; the soft contrast, which makes it the perfect blending material.

Necessary steps, among others, are darkening, changing the color temperature and applying some toning. You can really be creative here but my goal for this photo was to reflect the atmosphere of night time in the desert. This meant going for a very dark image that contains just enough detail in the landscape to interest the viewer.

Desert Nights – 15s + 0.7s | 16mm + 20mm | f/4 + f/9.5 | ISO 6400 + ISO 100 | Image Averaging + Time Blending + Focus Stacking

Conclusion

When you want to photograph the northern lights or when in addition to the stars clouds are moving across the sky, image averaging is not the right tool.

For photographing the Milky Way, though, it’s perfect. Combining image averaging with Time Blending allows you to create high-quality night images.

Learn More

Desert Nights Post-Processing Tutorial

Learn the complete start-to-finish workflow that Michael used to capture and process the image in his comprehensive video tutorial ‘Desert Nights‘. During the two-hour course, you’ll learn everything from taking the photos till preparing the final image for print. This is a great resource if you want to create high-quality night photography.