64 AUSTRALIAN SKY & TELESCOPE May | June 2018
SEAN WALKER /S&T(2)SNIGHTSCAPE COMPOSITIONNightscapesbeneitgreatlyfrom
good composition. Babak Tafreshi balanced this extremely bright
aurorawithitsdistortedrelectioninthewatersofastreaminIceland.SBLACK CRATERSOneofthefewplacesthatwillbetrulyblackin
agoodastrophotoistheshadowedregionwithinlunarcraters,like
thisimageofsunriseinthecraterClaviusdemonstrates.The same rules apply to nightscape photography. Balancing
your terrestrial and celestial targets in your picture frame
is how you unify the scene. If you’re planning to shoot a
young crescent Moon alongside the Eiffel Tower, the photo
might look better if you don’t cut off the tower’s base. Aurora
photography is the same way: Balance your subject with
elements in the foreground to make your photo attractive.
Composition is one aspect of astrophotography that you can
modify after the image is taken. Today’s digital cameras offer
dozens of megapixels that make cropping easy and relatively
painless. You can crop and rotate images of galaxies, nebulae,
and most any subject — as long as you have enough pixels to
work with. Cropping an image to better compose your subject
is relatively easy, particularly if your picture has lots of extra
space around the subjects. This is especially helpful when
shooting faint moving targets such as comets with tails that
are too faint to see through a camera’s viewfinder.Processing
Perhaps the most talked-about subject in astrophotography is
image processing. While everyone’s goal is surely to produce
the best image possible, it’s often tempting to add a little bit
more sharpening or to boost the colour saturation. Knowing
where to draw the line with the impressive tools available in
astro-imaging software is definitely a learning curve. It takes
time and experience to learn the difference between ‘just
enough’ and ‘going too far’.
In the best astrophotos, the viewer shouldn’t look at the
image and be able to identify which version of deconvolution
was used or how much noise-reduction was applied. Goodimage processing is essentially invisible; it should allow the
viewer to enjoy the picture without encountering processing
artifacts. Stars aren’t surrounded by dark rings, nor do they
have dark cores. Likewise, the limbs of planets shouldn’t
appear like a melon rind, with a bright arc along the edge.
These are all telltale signs of too much sharpening.
While I’ve listed some common attributes found in the
best astrophotos, there’s often much more to a stunning
image than a list to check off when shooting the night sky.
Some things you can’t put a finger on beforehand, but you’ll
often recognise what works in the final composition. Keeping
these elements in mind when planning and executing your
next image can help improve your imaging skills — and even
enable you to pull off your own masterpiece. SEAN WALKER has several imaging projects in the works,
though the biggest is an all-sky survey partnership that can be
seen at mdwskysurvey.org.IMAGING AESTHETICS