Sky & Telescope - February 2024 - 57

A MATTER OF (WHITE) BALANCE This triptych illustrates the creative options available when setting the white balance for a night-sky image. The
center panel is technically correct since it displays a neutral color with the Temp slider set to 4,000K. The frame on the left has the white balance set
to a cooler 3,000K value, which gives a wintery appearance. The panel on the right has a white balance of 5,000K, giving it a warmer cast.
high-ISO settings. This can give images
a grainy, sandpaper-like appearance.
You can minimize this problem by utilizing
Lightroom's Luminance and Color
noise-reduction sliders. Unfortunately,
these adjustments can also eliminate
some of the natural color variation
among stars - and you may even start
to lose faint stars.
Last year, Adobe introduced an AIpowered
feature called Denoise, which
uses machine learning to differentiate
between fine detail and unwanted noise
in a high-ISO image. It works remarkably
well on night-sky images - all with
the press of a single button! The default
setting seems to be effective, but if you
want to manually adjust the amount of
noise reduction there is a slider you can
tweak. A similar, standalone product
called Topaz DeNoise AI is also available
from Topaz Labs (topazlabs.com).
One advantage of shooting with a
standard camera lens is that you can
use Lightroom's built-in lens profiles to
automatically correct issues like distortion,
vignetting, and chromatic aberration.
In the Optics subsection, simply
click the Enable Lens Corrections box,
then select the Make and Model of the
optic you used for the photo. (If your
lens isn't listed, check the Adobe Lens
Profile Downloader.) The only time I
don't enable the profile corrections is
when I'm shooting with a fisheye lens.
Experiment and Tweak
At this point in the process, you should
have an image that's dramatically
different from what you started with.
Since every photo is unique, you'll probably
want to go back and revisit some
of the adjustments you've made. The
good news is that all the changes you
make to RAW files are completely nondestructive
and reversible. So, feel free
to experiment!
After I do an initial edit of my image,
I usually set it aside overnight to " let
it simmer. " I'll come back the next day
and see if there are any revisions I want
to make upon second viewing. Once
I'm happy with how things look, I move
on to cropping. It's the final step, and
it should be done after all other postprocessing
is complete.
The specific aspect ratio you choose
will largely be determined by how the
image will be displayed. Different social
media outlets have different requirements,
and if your goal is to create a
print you can hang on a wall, you'll
make different choices. Of course,
there's no reason why you can't create
different versions for each application.
After cropping, export your final
version in JPEG format. Before you do
this, take a moment to scan around
the perimeter of your image. This
" border patrol " can turn up unwanted
intrusions (such as a tree branch, or
half a star) that poke into the frame
and detract from the overall composition.
Tightening your crop a bit to
remove such distractions will instantly
strengthen your image. Like cutting a
diamond, it's often what you remove
rather than what you keep that will
ultimately make your photo sparkle.
Sharing and Feedback
It's worth remembering that there's no
" correct " outcome when it comes to
image processing - it's very subjective
and depends on your particular taste.
Regardless, make sure that all your editing
choices are completely intentional
rather than just accepting whatever
comes out of your camera. Don't be
afraid to experiment. If it makes for a
better photo, then go for it!
Finally, to improve your editing
skills, consider posting your final image
on one of the many online astrophotography
forums. You might get some
helpful tips and suggestions. However,
it's up to you to decide if the feedback
you receive is worth considering or not.
After all, the route you take on your creative
journey is yours alone to choose.
¢TONY PUERZER is a retired professional
photographer and an avid amateur
astrophotographer. He loves discovering
the details hidden in a properly exposed
night-sky image.
sk yand tele scope .o r g * FEBRUARY 2024 57

http://www.topazlabs.com http://skyandtelescope.org

Sky & Telescope - February 2024

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