Deep Sky Stacking Programs for Digital SLR Cameras

This document provides a summary of some available deep sky stacking programs. These programs each have their individual pro’s and con’s, and some are more suited to DSLR/mirrorless while others are more suited to dedicated astronomy cameras.
Please use this document as a starting place from which to find out more about these pieces of software and decide which is right for you.

Do you understand why you might stack image in astrophotography? If not you can check out pages such as this by Karl Perera who gives some nice examples of unstacked and the effect of stacking.

REGISTAR

This is a smart piece of software for aligning and combining individual astrophotographs from digital SLR cameras. It works very efficiently with large files, is amazingly capable in aligning photographs and has quite good stacking algorithms built in as a bonus.

This software is primarily intended for simply the registering (aligning) of frames such that they can be combined. This piece of software is so good that you can combine old film images with new digital images, or digital images from different cameras with different focal lengths and all sorts. It will also easily handle field rotation (fixed tripod shots are OK) and pretty much any other distortion.

Registar has limited file formats supported, check yours are compatible or convert your files first to TIF.

If considering Registar your primary other option will be PixIsngiht. Registar is designed more to do a good job of one thing (registering frames) whereas PixInsight is a more complete package.

The version of RegiStar that I am familiar with is 1.0, and it wasn’t updated for some time. Just recently in 2021 a new version of RegiStar was released so maybe there is yet life in this product?

Find RegiStar here: https://aurigaimaging.com/

DEEP SKY STACKER

Do you use a Mac? Yes? Move on – DSS is only for PC.

This is a free and very capable piece of software for aligning, combining and performing post processing of astrophotographs from digital SLR cameras. The best thing about this software is that it’s free, and amazingly capable for something that is free.

This software will read a wide variety of file formats including Canon RAW format, and process them. I have had some issues with processing canon RAW files with respect to getting good colour balance post-stacking so often choose to first convert the RAW files to TIF before processing. This may simply be a lack of experience on my part, as I do not use this software often.

The registering capabilities of Deep Sky Stacker are very good but do not match the capabilities of RegiStar or PixInsight when it comes to getting a good alignment of frames. There are often cases I find DSS will not correctly align frames where as RegiStar and PixInsight will.

I don’t tend to like the post-processing capabilities of Deep Sky Stacker so tend to finish my use of DSS at the point it has stacked the “Autosave.tif” and take that file in to PhotoShop from there to perform post-processing.

Deep Sky Stacker’s biggest advantage is probably it’s ease of use (very intuitive and easy to use interface) and it’s flexibility with it supporting all major file formats and handling various scenarios covering most astrophotography needs.

Find Deep Sky Stacker here: http://deepskystacker.free.fr/english/index.html

MAXIM

I primarily use MaximDL for image reduction, as it’s image reduction process is very painless. Provide it with a directory of all your reduction .FIT files and it will nicely sort them in to a database of reduction groups to be applied to any image you open. Open the .FIT needing to be calibrated/reduced and it will apply the appropriate reduction frames without you choosing reduction files of the correct temperature, binning, etc. This is significantly easier than any of the other packages which all require you to do more manual work with reduction frames. The benefits of MaximDL’s reduction frame handling for .FIT files may or may not be transferred to use of DSLR raw files – I have not tried reduction of DSLR images in Maxim.

MaximDL’ stacking seems fair however I haven’t had need to use it for alignment and stacking. I also haven’t tried MaximDL for large images such as DSLR, with the largest I typically use in Maxim being those from my SBIG ST8-XME.

Find MaximDSLR here: http://www.cyanogen.com/products/maxdslr_main.htm

CCDSTACK

CCDStack is one of a suit of products made by CCDWare aligned to advanced usage of telescopes.

I have used CCDStack a reasonable amount now for processing images from my ST8-XME astronomy camera and find it very usable and relatively powerful. I like features such as being able to see what data is being rejected by a sigma function on light frames and doing this very quickly and easily compared to PixInsight which shows you no preview before processing the full stack. This makes it very easy to tweak stacking parameters for a good result and apply different filtering to individual frames (such as when a satellite passes through a frame, applying harsher exclusion to that frame).

CCDStack will easily in only a handful of steps register your frames, normalise (apply weighting to) frames, apply data rejection to frames and combine frames in to a stack using weighting determined by the normalisation.

Find CCDStacker here: http://www.ccdware.com/products/ccdstack/

PIXINSIGHT

PixInsight is an advanced astrophotography image processing piece of software. I now have some experience using PixInsight for processing CCD images from an SBIG ST8-XME camera and RAW CR2 files from a Canon 6D DSLR and can certainly see the potential of the software.

If you ant a one-stop-shop for astrophotography image processing and you are happy to spend the $250 on PixInsight, there’s a very good chance you need none of the other pieces of software listed on this page. Having said that, you will be up for a steep learning curve.

PixInsight operates in a very different way to other software. They even seem to put buttons on dialogue boxes around the opposite way to what is most common just to confuse the user. The difference in how processing is done and the user interface in PixInsight makes the learning curve very steep and troubling at first. There are video tutorials online which are almost essential for getting an understanding of how to use the software before you lose your hair trying, but once concerned it is proving to be very powerful. It took me a few attempts coming back to PixInsight over a few months before I became familiar enough with it and stopped hitting brick walls to be able to process FIT and DSLR images with some confidence.

Where other processing software has failed to produce a good result of DSLR images (software such as using DSS, RegiStar and Photoshop) PixInsight has excelled and brought out more detail in images than I realised existed in the raw data. There is no doubt to my knowledge that PixInsight is the most advanced piece of software for stacking astrophotography deep sky images. It’s set of processes and plugins is both extensive and powerful. The catch is only in it’s usability and how patient you must be to work through its steep learning curve to achieve good results.

I would suggest if you are going to use PixInsight, start with DSS and understand the basics of astrophotography image processing before you begin the daunting process of understanding how to use PixInsight. Also, if you have easy to align good quality images then you will likely get a very good result from DSS in a much quicker time frame than PixInsight which will require you to perform more steps.
If you want to process DSLR images with PixInsight you will need a powerful machine to run it on. It will easily consume all of my 16 gigabytes of RAM on my Core i7 64bit windows machine when processing a stack of 20 DSLR images. Programs such as RegiStar work in a significantly smaller footprint.

PixInsight is available as 45 day free trial. Find PixInsight here: https://www.pixinsight.com/

STARRY LANDSCAPE STACKER

This is an Apple/Mac program and a great option for those who do not use Windows. It is effectively a good alternative to Deep Sky Stacker for those who use Apple PC’s.

Find Starry Landscape Stacker here: https://itunes.apple.com/au/app/starry-landscape-stacker/id550326617?mt=12

STARSTAX

StarStaX is a multi-platform image stacking software. From their website (below).

StarStaX is a fast multi-platform image stacking and blending software, which allows to merge a series of photos into a single image using different blending modes. It is developed primarily for Star Trail Photography where the relative motion of the stars in consecutive images creates structures looking like star trails. Besides star trails, it can be of great use in more general image blending tasks, such as noise reduction or synthetic exposure enlargement.

StarStaX has advanced features such as interactive gap-filling and can create an image sequence of the blending process which can easily be converted into great looking time-lapse videos.

StarStaX is currently under development. The current version 0.70 was released on December 16, 2014. StarStaX is available as a free download for Mac OS X, Windows and Linux.

Find StarStaX here: https://www.markus-enzweiler.de/StarStaX/StarStaX.html

ASTRO PIXEL PROCESSOR

Astro Pixel Processor is a complete image processing software package: https://www.astropixelprocessor.com/

I have trialed this software a few times but not used it heavily. The trials show it is fully featured and a good alternative to packages such as CCDStack and many even use in place of PixInsight.

Comparing Astro Pixel processor to PixInsight I would say it is easier to use but doesn’t have the depth of processing routines that come with PixInsight. That is to be expected as it is in many ways the huge array of functionality available in PixInsight that makes it more complex and bewildering to use. Astro Pixel processor has a more linear processing workflow, guiding you from one step to the next while still having all the capabilities to do quite advanced stacking and processing including mosaics.

Find APP here: https://www.astropixelprocessor.com/

SEQUATOR

Sequator is designed to be an easy to use light wait stacking program, aiming to make it easier for beginners to stack their nightscape and deep sky astrophotography.

Sequator has a simple and useful feature to mask foregrounds in nightscape images. While not 100% reliable simple tweaks when results are not perfect can often result in good results where the stars are stacked but foreground is not adversely affected by movement.

Sequator’s ability to align frames accurately is on par with Deep Sky Stacker where it seems to use simple rotate, translate and scale algorithms. This is often sufficient but none the less is less capable than algorithms used by the likes of PixInsight and RegiStar that will morph images as required to align stars across the field.

Sequator is free. Find sequator here: https://sites.google.com/site/sequatorglobal/download

AFFINITY PHOTO

Affinity Photo is a photo editing program like Adobe Photoshop. It differs in that it focuses on still image editing rather than having various other features such as video editing and 3D editing. Affinity Photo has a very capable advanced photo editing software.

Affinity Photo has built in stacking functionality for astrophotography. The options, configuration and features are somewhat limited but for simple users wanting to edit photos and occasionally do some stacking of simple Deep Sky and Nightscape images, it has the features required and is quite straight forward to use.

Affinity Photo has a free trial. Find Affinity Photo here:
https://affinity.serif.com/en-gb/photo/