Sky & Telescope - September 2021 - 66

S&T Test Report
because features in the chromosphere
change so quickly.
The SR-127 QT has a 9-pin serial port
that allows for software monitoring and
control of the telescope's filter bandpass
- a convenient option for imagers
like me. Users can download DayStar's
Quantum Control software for Windows
from the DayStar website, which works
seamlessly with the telescope. Connecting
the scope's filter to a laptop requires
an optional USB-to-serial adapter. A nice
feature of the software is that it searches
for the Quantum filter on all the available
ports on your computer, so you
don't have to figure out what COM port
your adapter is connected to. A graphical
display shows the settings and if the
filter is currently heating, cooling, or at
the desired temperature.
There are two additional accessories
DayStar recommends for imaging. The
first is their Interference Eliminator
($175). Because the light rays exiting
the etalon are parallel, they can often
cause a reflection between the camera
sensor's cover glass and the final surface
of the SR-127's filter that interferes
with the incoming light and produces
a moiré pattern on solar images. The
I also took a few images using a fullframe
mirrorless camera just to see if
it could capture the entire solar disk. It
almost fits, but not quite, as seen below.
To capture the entire Sun, you'll need
to add DayStar's Imaging Focal Reducer
(available on the DayStar website for
$285). In all other ways, using the
SR-127 QT was just like imaging with
a Quantum solar filter on one of my
other refractors.
Users will need to add a solar finder.
solution is to tilt the camera very
slightly. DayStar offers the Interference
Eliminator with either C- or T-threads
to connect to most cameras.
The other helpful accessory is
DayStar's FlatCap Imaging Diffuser.
This device makes flat-field calibration
frames in order to remove dust motes
from images and correct any uneven
illumination. The diffuser is placed over
the front aperture of the telescope, diffusing
the light entering the scope. You
simply point at or near the center of the
Sun and record the image to use as flatfield
calibration frames.
For Solar Aficionados
The SolaREDi SR-127 QT represents a
serious investment for the dedicated
solar observer or imager. Its long focal
length means that imagers should also
consider the additional cost of the focal
reducer and other accessories. But this
solidly constructed telescope is surprisingly
lightweight and can easily switch
back and forth between visual and photographic
use. I feel the chromosphere
model offers a good balance between
views of the solar disk and of prominences
that justify the extra cost.
¢ Contributing Editor RICHARD S.
WRIGHT, JR. enjoys observing stars,
including the closest one.
Left: Prominences are still clearly visible through the chromosphere version of the SR-127. Right: This image recorded with a Canon EOS Ra shows
the SR-127 QT doesn't quite fit the entire Sun on a 24×36-mm detector, requiring the addition of DayStar's optional Imaging Focal Reducer.
66 SEPTEMBER 2021 * SKY & TELESCOPE

Sky & Telescope - September 2021

Table of Contents for the Digital Edition of Sky & Telescope - September 2021