S&T Test Report
70 AUGUST 2019 • SKY & TELESCOPE
Live View
The Z6’s Live View offers three levels
of magnifi cation, permitting users
to zoom in on a star by up to 15× for
precise focusing. That’s not quite as
good as the D750’s 20× zoom level, but
it worked suffi ciently, especially when
combined with a Bahtinov focusing
mask on a telescope.
A bright Live View image, helpful
when framing with a DSLR, is essen-
tial in mirrorless cameras as they lack
any optical viewfi nder. The D750 has
an Exposure Preview option hidden in
the “i” button Menu with Live View
activated. Turning that on brightens the
Live View image. The mirrorless Sony α 7
III has an even more effective “Bright
Monitoring” mode equally well hidden
in its Custom button assignments.
The Z6 can achieve a signifi cant
boost in its live image brightness similar
to the Sony’s by switching the Z6 to its
Movie mode with the ISO set to Hi1
(ISO 102,400) or Hi2 (ISO 204,800).
Like most Nikons, the Z6 remembers
settings separately for its Still and
Movie modes, making it easy to employ
the Movie mode as a quick and tem-
porary means of brightening the Live
View image for framing nightscape
scenes. That’s very handy and produces
a much brighter Live View image than
the D750’s.Movie Mode
Where the Z6 really pulled ahead of its
DSLR equivalent, the D750, is in shoot-
ing movies. For one, the Z6 can shoot
4K movies (3,840 × 2,160 pixels) at 30,
25, or 24 frames per second. The older
D750 is HD (1,920 × 1,080) only.
The Z6 shoots movies using the full
width of the sensor, downsampling the
pixels in the process. When shooting 4K
video, lenses therefore provide the same
fi eld of view as they do when shooting
stills. That’s also true of Sony’s mirror-
less cameras but not of Canon’s new EOS
R and RP mirrorless models, which crop
4K movies by 1.8× or 1.7×, respectively.
But the huge improvement in movie
performance is in its noise levels. Even
at ISO 51,200, the Z6 looks acceptably
clean, unlike the D750, which is unus-able at its top speed of 51,200. At ISO
25,600 the D750 is still very noisy in
movies, far more than the Z6.
This improvement is important if
you would like to shoot real-time videos
of aurorae or of other nighttime events
such as star parties.
That said, the Sony α7 III is still the
winner for real-time low-light mov-
ies, as it can shoot at “dragged” shutter
speeds as slow as ¼-second, providing
a 2.5-stop increase in light input over
the Z6, which can shoot only as slow as(^11) / 25 -second at 24 frames per second. The
Sony remains my choice for real-time
aurora movies, but the Z6 will work
very well on bright aurorae.
Silent Shooting
Mirrorless cameras still have mechani-
cal shutters that close then re-open
quickly every time a photo is taken. The
Z6, as do other mirrorless cameras, has
a “Silent Shooting” mode that employs
an electronic shutter that is absolutely
quiet. Wedding photographers will love
it. For astrophotographers it can be
handy for completely eliminating vibra-
tion when taking high-magnifi cation
stills of the Sun and Moon.
I found telescopic images of the
Moon taken with Silent Shooting did
look ever so slightly sharper than those
taken with the mechanical shutter.
Combined with the Z6’s Continuous
Extended drive rate, which allows burst
rates of up to 8 frames per second with
uncompressed raw fi les, Silent Shoot-
ing should be great during total solar
eclipses for recording sharp diamond
rings, Baily’s Beads, and prominences.
pLeft: The rear screen is also a touchscreen, with an “i” menu that can be customized to include
favorite functions conveniently accessible by touch. Right: An “always-on” top OLED screen pro-
vides helpful exposure and battery life information during a long shoot. The rear LCD screen tilts
up for ease of use on a telescope when aimed high in the sky.
qThis series compares screen grabs from movies of the same moonlit scene shot with the three
cameras. The Z6 far outstrips the older D750 for movie performance, providing much lower noise
at the ultra-high ISOs required for low-light movies. However, the Sony α7 III provides slightly
lower noise than the Z6 and can shoot movies with shutter speeds as slow as 1/4-second, allow-
ing even slower and less noisy ISOs.
Sony α7 III
1/ 25 second
ISO 51,200
Sony α7 III
1/ 4 second
ISO 8000
Nikon D750
1/ 25 second
ISO 51,200
Nikon Z6
1/ 25 second
ISO 51,200