Sky & Telescope - December 2024 - 70

S&T Test Report by Alan Dyer
Nikon's Z6III Camera
This new mirrorless camera proves superb for
nightscape photography, with one shortcoming.
Nikon Z6III
U.S. Price: $2,499.95
Nikonusa.com
What We Like
Easy to frame
and focus
Good features for
night use
Excellent for
low-light video
and time-lapse
sequences
What We
Don't Like
Lower dynamic
range than
previous Z6 models
Sensor exposed
when changing
lenses
Some non-Nikon
batteries do not
work
WHILE ASTRO CAMERAS with cooled
CMOS sensors dominate the realm of
deep-sky imaging, traditional off-theshelf
DSLRs and mirrorless cameras
remain the prime choice for nightscape
astrophotography. However, Sony no
longer makes DSLRs, and neither Canon
nor Nikon has introduced a new DSLR
since early 2020. Only Ricoh/Pentax
remains stalwartly committed to DSLRs.
For every other camera brand, mirrorless
models fill their product lines.
I reviewed Nikon's original mirrorless
camera, the Z6 (S&T: Aug. 2019,
p. 68), shortly after it was introduced.
In mid-2024 the company issued the
third generation in its mid-level Z6
series. Like its two predecessors, the
Z6III offers a 24.5-megapixel,
backside-illuminated
(BSI) 35.9 ×
23.9-mm sensor with
5.9-micron-square pixels
in a 6,048 × 4,032 array.
Using a unit purchased
locally, I tested
it for the demands of
nightscape photography,
curious to see if ease of
use and image quality
have improved in the
model's third iteration.
70 DECEMBER 2024 * SKY & TELESCOPE
Noise Performance
We expect every new generation of camera
to offer incrementally lower noise.
However, in comparing the Z6III's
images to ones I shot in 2019 with the
original Z6, the new camera's noise
levels don't appear to be any different.
Noise was on par with other cameras
with similar megapixel counts. In samenight
tests, I found the new camera's
noise level comparable to my 20-megapixel
Canon R6 from 2020.
Images taken with equivalent
exposures over a range of ISO settings
showed noise increasing at each bump
up in ISO. Noise in nightscapes is most
obvious in dark foregrounds when they
are brightened in processing by raising
the Shadows slider, as I
did for my examples. In
my tests, ISO 3200 produced
good results, with
ISO 6400 quite usable
with today's AI-driven
noise reduction. Above
those ISO settings, I
judged the lifted shadows
too noisy to be usable.
Random hot pixels
that pepper long exposures,
especially on warm
nights, is the form of
The Milky Way rises above Takakkaw
Falls in Yoho National Park, British Columbia,
Canada, on a perfect July night. This is a stack
of two 3-minute untracked exposures at f/2.8
for the ground, blended with a stack of four
1-minute tracked exposures at f/2 for the sky
recorded at ISO 800 with the Nikkor 20-mm
lens on the MSM Nomad tracker shown below.
noise that can be independent of ISO.
This is the thermal noise that applying
dark calibration frames can eliminate.
Like most other cameras, the Z6III
offers a Long Exposure Noise Reduction
(LENR) option for taking a dark
frame and subtracting it in-camera.
This proved effective at getting rid of
the majority of hot pixels, which can be
difficult to deal with later in processing.
In sets of 8-minute dark frames
taken separately at room temperature,
there were no glows from warm
electronics or internal infrared heat
sources. Dark frames looked uniform.
While a Pixel Mapping option promises
to reduce hot pixels, I found it made
little difference.
While 24 megapixels is low by
today's standards, for nightscapes it's
a good balance of resolution versus
noise. While the smaller pixels
(or photosites) of higher-megapixel
cameras yield higher resolution, they
ALL IMAGES ARE BY THE AUTHOR
http://www.Nikonusa.com
Sky & Telescope - December 2024

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