Sky & Telescope - December 2023 - 69

rather than immediately transferring it
over USB prevents image corruption.
With its high quantum efficiency
and very low read noise, this camera
really excels at short exposure, deep-sky
image stacking, or " live stacking " (S&T:
May 2023, p. 60). It also works great
for longer exposures, with a deep well
capacity of just over 70,000 electrons,
and has virtually non-existent dark current
when cooled sufficiently.
I did much of my testing with fairly
short individual exposures. The sensor
has two readout modes: " normal " and
" low noise. " Compared to the " normal "
setting, the " low-noise " mode slows the
data readout from the detector slightly
in order to reduce read-noise levels.
Another setting that affects camera
read noise is gain. Typically, increasing
the gain reduces the read noise but
at the expense of dynamic range. All
Player One Astronomy cameras have
a " High Conversion Gain " setting, in
which the read noise drops significantly
while still maintaining a reasonable
amount of dynamic range.
This low noise profile and the chips'
91% quantum efficiency are an amazing
combination. With it I was able to
record galaxies from my fairly light-polluted
backyard outside of Orlando, Florida,
by stacking 1-minute luminance
or RGB filtered images. The Leo Triplet
(M65, M66, and NGC 3628) came out
quite well, though I couldn't pick up the
star stream extending from NGC 3628
even with many hours of one-minute
exposures. That feature definitely needs
darker skies than my backyard affords.
Longer exposures were never a problem
either. I took dozens of 5-minute
exposures of Sharpless 2-308, the
Dolphin Nebula, in Canis Major at the
Winter Star Party through a 3-nanometer
O-III filter on a Sky-Watcher
Esprit 150 refractor operating at f/7.
There was no hint of the amp glow that
plagued early CMOS cameras, or of
other pattern noise.
I used PixInsight to measure and
compare the mean pixel values of a
bias frame with 5- and 10-minute dark
exposures, all with the cooling set for
-10°C. The values were 202.1, 202.5,
The Poseidon-M PRO can also be used for photographing the Sun, Moon, and even the
planets. This full-disk solar image was recorded at 15 frames per second using an Astro-Physics
92-mm refractor and an Altair Astro Herschel Wedge (reviewed in the March issue, p. 68).
and 202.7 units, respectively - dark
current is detectable but negligible
for all intents and purposes. Even the
10-minute exposure showed no traces
of amp glow or similar artifacts.
The exceptionally clean images are
likely attributable to Player One's proprietary
dead-pixel suppression (DPS) technology.
This internal process eliminates
dead pixels or hot pixels by replacing
them with an average value of adjacent
pixels, much like some post-processing
software does with a bad pixel map. A
company representative told me the DPS
pattern is a static map captured as part
of the camera's quantitative analysis
process. Over time, this static map will
need to be updated.
One feature I greatly appreciated
with the Poseidon-M PRO is that its
sensor chamber window includes a
dew heater. I live in a high-humidity
climate where it's common for a cooled
camera to develop condensation on the
sensor's protective window. As such,
I consider this feature a " must have. "
Users adjust the heater setting through
camera-control software, to work with
local conditions.
Speaking of condensation control, I
couldn't find anything on the company's
website about the internal sensor chamber's
moisture mitigation, so I emailed
Sean Wang, CEO of Player One Astronomy.
He told me the chamber is sealed
but contains a strong desiccant that
should last for years. In time, he said, the
company would have a product available
for users to replenish this themselves
(and it will eventually need refreshing).
Thanks to its low noise and troublefree
operation, I feel the Poseidon-M
PRO is a high-quality, solid performer
for monochrome imaging with filters. I
consider it a top choice for both beginners
stepping up to their first dedicated
astronomy camera and for seasoned
imagers seeking a worthy upgrade.
¢ Contributing Editor RICHARD WRIGHT
is a software developer and lifelong
amateur astronomer. He loves combining
both interests on late nights and
weekends.
sk yand tele scope .o r g * DECEMBER 2023 69

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Sky & Telescope - December 2023

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