Sky & Telescope - December 2024 - 72

S&T Test Report
then up, increasing the ISO made little
change - noise remained similar. How
can this be?
The difference here compared to the
" ISO versus Noise Comparison " set in
the middle of page 71 is that now the
exposure time (15 seconds) and aperture
(f/2) aren't changing, so the same
number of photons are hitting the
sensor for each exposure. The signal is
constant. In practice, this means that
when shooting nightscapes with the
Z6III it's best to use an ISO of at least
800. Brightening low-ISO images after
the fact produces poor results for dark,
starlit scenes. Twilight and moonlight
scenes are more forgiving.
Focusing and Framing
The Z6III provides great aids to getting
images that are accurately framed
and focused. It offers a Starlight View
option, a feature shared with all of
Nikon's most recent cameras. Activating
it brightens the live view enough to
show the Milky Way and at least the
silhouette of a dark foreground. This
minimizes the need to shoot lots of
high-ISO trial-and-error framing shots.
The auto-focus system also proved
sensitive enough to work on stars, at
least when the camera is paired with a
fast lens. Auto-focusing by tapping on
a star on the rear touch-screen proved
quite accurate. Manual focusing is also
easy to do. The Z6III offers magnifications
up to what the camera calls
200% for precise focusing by hand.
Even better, when turning on the
camera, auto-focus lenses snapped to
their infinity setting by default. That
was the case not just with the 20-mm
Nikkor lens I used but also with the
third-party lenses I tested with the
camera - a huge convenience when
shooting under the stars. I wish my
tTop: While the Nikon Z6III has a mechanical
shutter, it remains open even when the camera
is switched off. This risks exposing the sensor
to dust. Upper middle: Like Canon cameras, the
Z6III uses a flip-out, vari-angle screen, rather
than Nikon's usual tilt-up screen. The design
facilitates shooting at any orientation. Lower
middle: The top panel features a backlit LCD
displaying settings and running countdowns of
times in extended exposures, time-lapses, and
LENR darks. Bottom: Ports include USB-C (top)
for file transfer and external power, a full-size
HDMI (middle) for video out, and a proprietary
DC-2 shutter release port like other Nikons.
Canon cameras could do that!
Astro-Friendly Features
While the Z6III doesn't have any unique
attributes for astrophotography, it does
include the same night-friendly features
found on other late-model Nikons.
For example, in the Custom Settings
menu, turning on Extended Shutter
Speeds allows internally timed exposures
as long as 900 seconds (15 minutes).
You can combine those with the builtin
intervalometer to set up sequences
of multi-minute exposures without the
need for an external intervalometer. I
did wish for a 45-second option between
the standard 30-second setting and the
next jump up to 60 seconds.
The Exposure Delay setting provides
up to a 3-second delay between pressing
the shutter button and the start of
the exposure, to minimize vibration
without needing a remote release. This
is better than using a self-timer, as it
avoids that function's annoying beeps
ISO 100
8 minutes
0 EV
Correct
ISO 100
15 seconds
−5 EV
Under
ISO 200
15 seconds
−4 EV
Under
ISO 400
15 seconds
−3 EV
Under
ISO 640
15 seconds
−2.35 EV
Under
ISO 800
15 seconds
−2 EV
Under
ISO 1600
15 seconds
−1 EV
Under
ISO 3200
15 seconds
0 EV
Correct
ISO 6400
15 seconds
+1 EV
Over
ISO 12800
15 seconds
+2 EV
Over
This series begins at the far left with a properly exposed image recorded at ISO 100. Each subsequent image is underexposed by using a very
short shutter speed. Gradually increasing the ISO brightens the images but yields poor results until the Z6III's second " base ISO " of 800 is reached,
where the noise level suddenly improves.
72 DECEMBER 2024 * SKY & TELESCOPE

Sky & Telescope - December 2024

Table of Contents for the Digital Edition of Sky & Telescope - December 2024