Sky & Telescope - September 2024 - 68

S&T Test Report
Jupiter, Saturn, or the waxing Moon
showed any noticeable false color in the
included 22-mm eyepiece, and the views
were quite sharp in the middle of the
field. I could see a good bit of distortion
starting about ¾ of the way from the
center to the edge of the field, as would
be expected in an f/4 reflector without
a coma corrector in place (the corrector
included with the 150P is for photographic
use only).
I was curious if the Quattro would
make a good rich-field telescope. It
certainly has a generous field of view
and sufficient aperture to provide that
" spacewalk " effect. However, it really
needs a visual coma corrector such as
Tele Vue's Paracorr and a more complex
eyepiece to perform as a great rich-field
telescope. Alas, this would more than
double the cost of the entire system!
Still, I used an assortment of eyepieces,
and, aside from the coma, I found the
views quite satisfactory, with the higher
magnification views having progressively
less distortion. I did try a Tele Vue
Ethos eyepiece, and what a nice, lovely
field it would have been had I had a
visual coma corrector, but without one
only the middle of the field was satisfactorily
sharp.
Photographic Performance
While this scope can be used for visual
observing, the inclusion of a photographic
reducer/corrector is a pretty
good indication that its main intention
is for use as an astrograph. The corrector
connects to your camera via a
M48-male-threaded interface and has a
2-inch barrel that slides into the focuser.
Its back-focus requirement of 55 mm
works perfectly with most modern astronomical
cameras or a DSLR/mirrorless
camera adapter, though you should note
that it will only produce a corrected
field large enough for a crop sensor
camera. I used the scope with a Player
One Poseidon-M (which I reviewed
in the December 2023 issue, p. 66), a
tThe primary mirror is secured with three
clips, each held in place with a pair of black
Philips-head screws.
color Player One Ares-C, and once with
a full-frame Canon EOS Ra mirrorless
camera in order to assess the size of the
corrected field. Taking an exposure of
M45 (seen below) shows the corrector
can cover an area noticeably larger than
the stated APS-C format.
I had some concerns about the fast
focal ratio making the scope difficult to
keep in collimation. I had to fine-tune
my initial collimation slightly using an
out-of-focus star with a camera when I
transitioned from visual to imaging use,
but afterwards I never needed to adjust
collimation again, even after driving
with it to my dark-sky site over 160 km
(100 miles) away. The open back on the
primary mirror cell allowed the optics
to reach ambient temperature quickly -
I was ready to start imaging after about
30 minutes in a typical evening starting
around 70°F at sunset.
I'm a bit spoiled by electronic focusers
and groaned inwardly about having
to focus this scope manually. It turns
out that good focus was fairly easy
to achieve with the fine-focus knob.
The focuser never slipped with heavy
Left: The image below is taken with a full-frame camera (EOS Ra), with a rectangle showing the smaller field of an APS-C sensor recommended as
the maximum field coverage when using the focal reducer/coma corrector. Right: Zooming in on the top right corner shows the image is well-corrected
for APS-C detectors and would be acceptable for slightly larger sensors.
68 SEPTEMBER 2024 * SKY & TELESCOPE

Sky & Telescope - September 2024

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