Akastroid vs DeepSkyStacker

The short answer

Stay with DeepSkyStacker if you are on Windows, you already finish your stacks in Photoshop or GIMP and enjoy that part, and your mount tracks well enough that frame rejection is not a problem you have.

Try Akastroid if you are on a Mac, where DeepSkyStacker does not run (the usual workarounds are Wine or a virtual machine). Also if you shoot on an alt-az mount or a smart telescope, if you get stuck on the step after stacking, or if you image planets too and want one program for both.

Where DeepSkyStacker is better

It is free, permanently and without a frame limit, and that should be weighed first. It has been in use for two decades, so almost any problem you hit has already been written up on a forum somewhere. No newer program has that much community help around it.

It also gives you complete manual control of which frames go in and how they are combined, with no opinion of its own. If you have already learned what those settings do, being asked for them is a feature rather than an obstacle.

Where the two differ

The stack is not the hard part any more

Stacking is settled mathematics. Align the frames, reject the outliers, average what remains, and the noise falls with the square root of how many frames you had. Every serious program does this correctly, and I would not trust a comparison that claims a big difference in integration quality between two competent stackers.

What is not settled is everything around it. Which of your frames were ruined and by what. Whether the field rotated. Where the sky gradient is and how to remove it without taking the nebula with it. What the real colors are. How far to stretch before the background goes gray. Those steps decide how the picture turns out, and DeepSkyStacker leaves them to you and whatever you open the result in.

Field rotation

Akastroid registers by matching star patterns rather than searching for a shift, so a field that rotated between exposures still aligns. This is the case that decides whether an alt-az session stacks at all (a Seestar, a Dobsonian, an undriven mount). When it goes wrong it shows up as stars streaking into arcs toward the frame corners when it goes wrong.

Rejections that say what was wrong

Twelve measurements are taken on every frame: star size and shape, star count, drift, background level, gradient strength, noise, signal-to-noise, cloud, satellite and aircraft trails, focus and clipping. Each rejected frame names the fault, so the frame table shows the hour the transparency dropped or the dew arrived, not just a pass or fail. Any rejection can be overruled with a click. See Image Doctor for what each measurement means.

The half of the workflow that comes after

Gradient removal, photometric color calibration against 1.48 million cataloged stars, a stretch set from your own histogram, deconvolution with a point spread function measured from your own frame, and denoising scaled to the stack's measured noise. In a DeepSkyStacker workflow all of that happens in another program, by hand. The full workflow is written out here.

Planets and the Moon

DeepSkyStacker does deep sky. Akastroid also reads SER and AVI captures, grades every frame for sharpness, aligns in pieces to remove the atmosphere's local warping, corrects atmospheric dispersion and sharpens with wavelet layers. That job is normally split across PIPP, AutoStakkert and RegiStax.

What Akastroid does not do

Its adjustments are global: it has no masks, layers or selective editing, so a correction applied to the core is applied to the background too. If your workflow depends on luminance masks, this is not the tool for the finishing pass. It still works as the front half, because the integration can be saved before any finishing and taken elsewhere.

The free tier is capped at three processing runs and one export, not by feature or frame count. Every session stacks in full, twenty frames or five hours of them. After that it is a one-time payment, against a program that is free without limit.

Try it on the same data

The comparison that matters is on your own frames. Point both at the same folder and look at the two results. The wider comparison, including Siril, PixInsight and AutoStakkert covers the rest of the field.