Why StarStaX?

In modern landscape astrophotography, creating Star Trails by taking hundreds of shorter exposures is preferred over a single, hours-long shot. This approach has a key practical advantage: if a flashlight shines into the lens, a car passes by, or the tripod gets bumped, you simply discard that single frame rather than losing the entire night’s work. To combine these frames into a final image, StarStaX is the go-to free software. It is lightweight, fast, and dedicated specifically to this task.

How It Works?

The “Lighten” Mode StarStaX does not sum up light in the traditional way (which would result in an overexposed, white image). It uses the “Lighten” blending mode. The software analyzes every pixel across all images and selects only the one with the highest brightness value for the final output.

• This ensures bright stars “overwrite” the dark sky background.

• Noise in the shadows does not accumulate, keeping the final image clean.

The Gap Problem and “Gap Filling”

There is always a tiny delay between shots (time for the camera to write the file to the card). As a result, after stacking, star trails might look like dashed lines (“beads on a string”). StarStaX solves this with the Gap Filling feature. The algorithm analyzes the end of a star trail on one frame and the beginning on the next, mathematically interpolating the missing segment. The result is perfectly smooth arcs, even if your camera has a slower buffer.

“Comet Mode” Option

An interesting addition is the Comet Mode. The software simulates a gradual fading of the star trail, adding dynamics and a sense of motion to the image, resembling a meteor shower or comets.

Creating Star Trails is one of the most spectacular astrophotography techniques. In this comprehensive step-by-step tutorial, you will learn how to stack a series of individual frames into one stunning image using the free StarStax software. This guide includes the essential step of RAW file conversion to a lossless 16-bit PNG format using RawTherapee, and it’s friendly for Linux users (as it uses free, multi-platform tools).

Capturing Star Trails in a photo is not to difficult task. There are several schools to do this. The Internet has many descriptions and videos on how to do this. I think I’ll never become a YouTuber, personally I prefer to create a document or simple instruction that describe the whole ho-to process in clear technical language and this was what it guide me during preparation this description.