How I have been using Sequator thus far in my astrophotography learning journey
Around two years in now to learning, from scratch, i.e. no
knowledge base whatsoever, how to
·
Use my DSLR in manual mode
·
Do some basic astronomy using a beginner’s
telescope
·
Complete some basic astrophotography – both deep
space targets and milky way landscapes
One of the free software programs I got to grips with early
on was Sequator – mainly for stacking my very limited milky way landscape images.
Below I outline my Sequator work flow.
Remember, this blog is written by a complete beginner to
astronomy and astrophotography – for other complete beginners! Essentially it
is a record of my learning journey in these fields. Mistakes, warts and all!
I am doing this post on Sequator today because some one
emailed me and asked if I had any basic workflow notes for a complete beginner.
They had been looking at my ‘Beginner’s guide to taking your first milky way
photograph’ series; in one blog post I mentioned my using Sequator but didn’t expand
on it. Luke, this post is for you buddy.
Firstly, lets start with – What is Sequator?
It is a free, at the moment, software for windows platforms.
It stacks and aligns RAW or TIFF file night sky images, and in doing so removes
random noise. An added advantage? It handles images with a little bit of
foreground in them. All the better then! And, bonus, it will help with other
challenges such as light pollution, distortion, hot pixels, etc. I found the
basic functions quick and easy to learn, understand and set up ad I have put my
workflow notes on sequator further down this post. Remember, I am a very new
beginner astrophotographer. So, I am sure I have missed things out, for which I
apologise. But the aim of this post is to give you something to work with
initially if it is the first time you have come across Sequator.
As well as light images, you can add darks and flats as well.
The basic settings for processing the images are straight forward. There are
other options that can be selected depending on the images being stacked and
these are explained in the manual which can be viewed here: https://sites.google.com/view/sequator/manual
Here then is my beginner’s workflow using sequator:
1.
Sometimes, not always, I may batch edit my lights
before placing into sequator – using affinity photo – NOTE: only edit exposure,
contrast, highlights, shadows, and WB – I am aiming to try and reveal further
detail from shadow areas and prevent blowing out of brighter stars - if you do this, save them as TIFF files at end
2.
Open ‘Star Images’ – drag and drop light
images into sequator (SQ) NOTE: star frames = lights; noise images = darks –
use same number of these as lights added – at least 5 - 8; vignetting images =
flats
3.
Check ‘output’ box and name file – save as
Tiff 16 bit file
4.
SQ automatically selects image as base image
– double click base image to choose image I want.
5.
Composition – ‘align stars’ for all
images with foreground or just milky way and/or stars. (If doing star trails –
select ‘trails’ instead). On ‘Accumulation’ – select ‘best pixels’ –
slider across to HIGH – this will remove satellite and plane trails from final
image
6.
Click ‘freeze foreground’ (bottom LHS) if
images contain foreground elements. Check box ‘selective’ alongside. Slider
across to ‘strict’. Select ‘best pixels’
7.
Sky region – allows you to help Sequator decide
which part of the image is sky and which part is foreground. Use ‘boundary line’ if you have a flat
non punctuated horizon line between sky and foreground. Use ‘irregular mask’
for complicated horizon or foreground objects punctuating it. Mouse scroll
wheel will green paint in sky area. Leave little gap between foreground and sky
that has been blanked out. (Right mouse click = eraser for mistakes). Click ‘auxiliary
highlight’.
8.
Auto brightness – off. HDR – off (although
try as on if different exposure levels between images – if final image is over
exposed – redo and check both these to on) ‘Remove dynamic noise’ – on.
It removes hot pixels – especially useful if images are long exposure ones. If
not using dark images – reduce distortion effects – I keep on ‘auto’ as it
seems to remove any star streaking in the outer edges and corners of my final
stacked image.
9.
Check ‘light pollution’ – only if present
in images. Check ‘uneven’ or ‘deep sky’ – depending on conditions. Don’t apply
light pollution too aggressively. I find it gives horrible results and so
unless there is major light pollution – I don’t use it.
10.
Can check ‘intelligently aggressive’ box
or leave unchecked an use slider to determine how much light pollution
compensation to apply. Default – check the box.
11.
Check ‘reduce distortion effects’ box to
auto. Check ‘complex’ box at bottom
12.
Ignore rest of boxes on menu
13.
Click ‘start’
14.
On final image – zoom in and check any areas
with trees etc for stacking artefacts etc.
Sequator can be used for star trails as well. I haven’t done
any star trail work yet but if you are interested here are two websites that
give tips:
Star trails in sequator
https://www.skyatnightmagazine.com/astrophotography/star-trails-software-sequator
stacking milky way images in sequator
https://www.ntounas.gr/how-to-stack-milky-way-photos-using-sequator/
Two videos about Sequator that I found useful were:
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