skyandtelescope.com • AUGUST 2019 71Deep-sky Imaging
The tough test is long-exposure deep-
sky imaging. Problems that can remain
hidden even in nightscape images can
become visible in exposures lasting
many minutes, especially after applying
the high levels of contrast required to
bring out deep-sky targets.
However, the Z6 passed the test
admirably. I saw no edge shadows from
masks or mechanical obstructions in
front of the sensor, which is as a mir-
rorless sensor should be. By comparison,
DSLRs produce a darkening along the
bottom of the frame due to shadowing
from the upraised mirror.
Unlike in the Sony α7 III, I saw no
discoloration or oddly colored glows cre-
ated by internal heat or light sources.
Stars also appeared neutral, with no
strange green stars or anti-aliasing
effects. In comparing Z6 images to ones
taken with the Nikon D750, stars were
not “eaten” or smoothed out by internal
fi rmware routines.
Using Long Exposure Noise Reduction
to apply dark frames internally by the
camera did not introduce any image arti-
facts, such as blurred or discolored stars.
The limited loan period didn’t
allow me to test the Z6 on a moonless
night targeting nebulae to check its
red sensitivity, but I would not expect
it to be any better than other stock
DSLRs for picking up faint H II regions.
LifePixel (lifepixel.com) and Spencer’s
Camera&Photo (spencerscamera.
com) both offer services to modify the
Z-series cameras with a fi lter that trans-
mits more Hα signal.
File Compatibility
The Z6 writes raw fi les in Nikon’s NEF
format. However, as with all camera
brands the exact fi le protocol varies
from model to model. As of this writ-
ing in early 2019, the mainstream raw
developers from Adobe, Affi nity, DxO,
Luminar/SkyLum, and ON1 opened Z6
fi les without problems.
However, specialized astronomy
image-processing programs, often reli-
ant on the good graces of independent
developers, are slower to catch up and
might not open Z6 raw fi les. For exam-
ple, PixInsight v1.08.06.1473 (issued in
May 2019) did not, even with the new
LibRaw module installed.
Fortunately, the free open source raw
developers Darktable v2.6.0, LightZone
v4.1.9, and Raw Therapee v5.6 all opened
Z6 fi les, though doing so might require
also updating your computer operating
system to the latest version.Control Options
New cameras also often come with
unique protocols for allowing external
hardware and software to control the
camera. Just because you have softwarethat will run Nikon cameras doesn’t
mean it will run a Nikon Z6, or any
new Nikon for that matter. For exam-
ple, BackyardNIKON v1.0 did not work
with the Z6.
AstroPhotography Tool (APT v3.63)
did run the Z6 just fi ne, using the
USB-C to USB-A cable that comes with
the camera. That connection allows APT
to shift shutter speed, ISO, and even
lens aperture using its scripting func-
tion. For other programs, best check
with the developer for compatibility.
However, to keep things simple at
the telescope, I usually prefer to controlpThe Z6’s Silent Shooting mode employs an electronic shutter to eliminate noise and vibration,
which is particularly helpful for getting sharper solar and lunar images shot through a telescope.pLong exposures taken with the Z6 were free of amplifi er glow and sensor shadowing, yielding
clean images. This is a single 4-minute exposure at ISO 400 taken in moonlight to show fi eld il-
lumination. The vignetting is inherent in the 105-mm refractor and fi eld fl attener employed (no fl ats
or lens correction were applied here). The blue glow at the top right is from a star just off the frame.Nikon Z6 with mechanical shutter Nikon Z6 with silent shutter