Sky & Telescope - August 2022 - 62

RICHARD S. WRIGHT, JR. (2)
Imaging Trends
The Times They Are A-changin'
We saw one revolution already at the close
of the 20th century. Film astrophotography,
with its chemical processes, darkroom
artistry, and gas-hypering alchemy, gave way to
the environment of digital cameras, specialized
computer software, and the virtual darkroom.
But even that familiar scenario will eventually
become the exception rather than the rule.
Everything having to do with astrophotography is changing,
including the optics we use. Commercially produced
telescopes and camera lenses are better than ever, thanks
both to advances in computer-formulated optical designs and
the addition of new materials such as extra-low-dispersion
glasses. Fast, high-quality optics are easily accessible and
more affordable than ever. For example, with a mirrorless
camera with a tripod and an f/1.4 lens, you can now record
a Milky Way image in under 10 seconds with equipment that
doesn't cost a small fortune. An f/7 telescope, once considered
photographically " fast " by deep-sky imagers, is now
passed by unless it's paired with a reducer/flattener. Scopes
with focal ratios of f/5 and f/4 are now the norm, with even
f/2 instruments available from several manufacturers. I currently
own three telescopes that produce sharp, round stars
across a full-frame camera sensor at f/3 and faster - a feat
that was until recently considered prohibitively expensive.
The same goes with the detectors in our cameras. CMOS
chips today exceed the performance of CCDs. Some CMOS
camera manufacturers are closing in on the effective elimination
of read noise and achieving the maximum quantum
efficiencies possible for digital detectors. What's next? I have
some ideas, and I'm not the only one.
FAST AND DEEP This image of the Milky Way was recorded with a
single, 10-second exposure made with a Canon EOS Ra operating at
ISO 3200 and an f/1.4 Sigma Art lens on a stationary tripod. The same
photograph taken with a DSLR a dozen years ago would have been
riddled with noise and would have barely shown our galaxy at all.
AI FOR YOUR DSLR Products like the
Arsenal 2 add a Graphics Processing Unit
(GPU) to your camera for remote-controlled
computational photography assistance. This
device adds new capabilities to your camera,
including focus stacking, high-dynamicrange
compositing, and even accurate
auto-focusing on star fields.
Computational Photography
When a process can't be improved,
the only thing left to do is to change
the process. Any student of modern history understands that
today's amazing, leading-edge, expensive technology is only a
few years away from being cheaper and small enough to fit in
your pocket or strapped to your wrist. A good example is my
Apple Watch. It can monitor my heart rate, read my bloodoxygen
level, make international phone calls for free, and, if
I ask it to, find all the dog photos on my paired smartphone.
We already live in the future!
The next big buzzword creeping into the conversation
about astro-imaging is computational photography. In fact,
computational photography is already revolutionizing photography.
You're most likely already taking it for granted.
Computational photography is when computer processing
is used to aid or improve photography in-camera. We
already have handheld cameras (in your smartphone) that
combine multiple exposures of varying lengths to create
high-dynamic-range (HDR) images. That same smartphone
camera will take as many as a dozen or more very short
images in low light, then align and combine them to make
a single, low-noise image - all happening automatically in
your device while you watch. Today I can take a 5-second,
handheld exposure in low light without a tripod, and it
won't be a smeared mess. These are all examples of computer
processing being applied while the image is recorded
to dramatically improve the capabilities of our cameras and
the quality of our photos.
This technology is still in its infancy, as improving computational
power continues to increase the capabilities of
image- and graphics-processing technologies. In every case,
industries outside of astrophotography are driving these
technologies forward. You're probably familiar with a Central
Processing Unit (CPU) - the " brain " at the heart of most
computer systems. Another acronym you may be less familiar
with is GPU, or Graphics Processing Unit, a term coined by
the hardware graphics accelerator company NVIDIA in 1999.
Today, GPUs power 3D simulations and games in computer
and gaming consoles, and the performance improvements
they've made possible are staggering. Computer images are
simply numbers, and a modern GPU can perform trillions
of numeric calculations every second, making those 3D-rendered
games run smoothly. Many of the latest advances in
our smartphone-camera capabilities have arisen because your
smartphone, just like your laptop or desktop computer, now
comes with an integrated GPU.
62 AUGUST 2022 * SKY & TELESCOPE
Sky & Telescope - August 2022

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