Sky & Telescope - July 2024 - 71

the app rightly encourages users to
take dark frames, to record the thermal
noise that builds up during each
exposure. A Darks routine does that
automatically over 20 minutes, with the
instructions advising the user to place
the Dwarf II in its black bag and in a
dark location. This needs to be performed
only once, not each night.
The resulting dark-frame library
(totaling 800 megabytes on the microSD
card) contains a series of 15-second
exposures over a range of sensor-gain
levels at both 2K and 4K sizes. The
appropriate darks (three are taken at
each sensor setting) are then automatically
subtracted from each incoming
image with the matching gain setting.
It's a basic level of image calibration, but
without it you'll get a blizzard of colorful
hot pixels in your image.
For electronically assisted astronomy
(EAA), the Dwarf II provides
presentable images after only a minute.
But to acquire the best images to keep
on file, the more exposures you stack
the better. However, shooting more
images introduces more field rotation.
While the live-stacking routine
aligns the images well, an increasing
amount of the frame becomes unusable
with longer exposures due to twisting
artifacts at the corners, requiring ever
more cropping of the already small
image the system produces.
DwarfLab recently endorsed one
solution to the field-rotation problem.
While it was initially designed to be used
in alt-azimuth mode, the little Dwarf
The filtered Sun is seen at right with both
the main and smaller finder lenses, using the
solar filters in place over both lenses as seen
below. In either Photo or Video modes, hitting
Sun Track initiates tracking good enough to
keep the Sun centered for an hour or more.
II (unlike most other
smartscopes, at least
officially) can be tilted
and polar aligned for
use as an equatorially
mounted telescope.
While the app has no
" equatorial mode "
per se, the three-field
calibration and Go To
pointing work perfectly
well with the
Dwarf II polar aligned.
Doing so allows longer
stacks with minimal
edge artifacts, even for
targets crossing the
zenith.
However, tipping
the Dwarf II over
equatorially requires
bolting it to a solid
tripod, ideally with a geared three-axis
head. The included tabletop tripod and
small ball head are adequate only for
use in alt-azimuth orientation, and only
then if set on a solid table or on the
ground when there's no wind.
You can download the stacked, final
image from the DWARFLAB app to your
mobile device's photo gallery as a JPG,
for basic processing and sharing on
social media. For most users that will be
sufficiently satisfying.
However, the individual FITS files
allow you to pursue more advanced
processing. A favorite program among
ambitious Dwarf II owners is Siril
(siril.org), which is free for MacOS and
The result of M42 seen at
left was stacked in-camera
and looks presentable. At
lower left, the author stacked
and processed the separate
FITS files with Siril, then finished
by adjusting the image
with Adobe Photoshop.
Windows but comes with
a steep learning curve.
From the images
I shot, and the best
examples posted by
other users, I think it's
fair to say that even
with advanced processing,
images will always
suffer from either noise
or a loss of detail due to
aggressive noise reduction.
But it's worth
remembering that getting
award-winning images is not the goal of
a small smartscope like this.
Bottom Line
If the Dwarf II cost the same as a conventional
astrophoto rig or high-end
smartscope, I'd be much more critical.
But for its price it provides great value
for anyone, young or old, getting into
deep-sky imaging or into the hobby,
period. I had a lot of fun with it. I think
others will, too.
¢ Contributing Editor ALAN DYER is
co-author of The Backyard Astronomer's
Guide. He can be reached through his
website at amazingsky.com.
sk yand tele scope .o r g * JULY 2024 71
http://www.siril.org http://www.amazingsky.com http://skyandtelescope.org
Sky & Telescope - July 2024

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