Sky & Telescope - July 2020 - 68

S&T Test Report by Dennis di Cicco

QHYCCD's
New 60Megapixel
Camera
CMOS detectors are the future
of astroimaging, and the new
QHY600M camera is giving us
a state-of-the-art taste of that
future today.

U.S. Price: $5,000
qhyccd.com

What We Like
Extraordinary image
resolution
Fast readout
Short back focus

What We Don't Like
Difﬁculty achieving quality
ﬂat-ﬁeld calibration.

THERE'S A LOT TO TALK ABOUT

with the new QHY600M camera from
QHYCCD, so let's jump right in. And
the ﬁrst thing there's a lot of is pixels -
62,393,796 of them, according to the
spec sheet for Sony's IMX455 back-side
illuminated, full-frame, CMOS sensor,
with slightly more than 61 million of
them active imaging pixels. To put that
into a bit of personal perspective, I got
my start in digital astrophotography
about 30 years ago with several cameras
built around the TC211 CCD sensor
made by Texas Instruments. It was
68

J U LY 2 0 2 0 * S K Y & T E L E S C O P E

small but still boasted nearly 32,000
pixels. Just one square millimeter of the
QHY600M's chip contains more than
twice that many pixels.
All those pixels translate into a chip
capable of extraordinary image resolution. In theory, the QHY600M can
resolve about 133 line pairs per millimeter. If we spin the clock back a few
decades, that kind of resolution would
typically outperform Kodak's Technical
Pan ﬁlm, the last great heartthrob for
amateurs in the days of emulsion-based
astrophotography. The QHY600M is the
kind of camera many amateurs have
long wished for - the resolution of ﬁnegrain ﬁlm coupled with the sensitivity
of modern digital detectors. But, as
the saying goes, sometimes we should
be careful what we wish for. Hold that
thought for now.

Hardware
The QHY600M's vital speciﬁcations
are listed in the camera manual,
which can be downloaded for free
from the company's website (qhyccd.
com), so I'll only highlight a few
here. The camera body reminds me of
a large beverage can. It's 3½ inches
(90 mm) in diameter, 7 inches long,
and weighs 2 pounds (0.9 kg). The

p The QHY600M camera comes with an AC
power supply, a full complement of cables, a
2-inch nosepiece, and a set of spacers that
allow expanding the back-focus distance between the nosepiece and the camera's CMOS
detector up to an additional 17 millimeters in
increments as small as ½ mm.

chip is set back only 17½ mm from
the front of the camera body, but this
distance increases to a minimum of
about 26 mm when the mounting ring
and 2-inch nosepiece are in place. An
included set of spacers allows stretching this setback an additional 17 mm
in ½-mm increments - a nice feature
for anyone needing critical back focus
in an optical system.
I tested the QHY600M paired with
its mating QHYCFW3 ﬁlter wheel,
which comes with two carousels; one
for nine 50-mm-round ﬁlters and the
other for seven 50-mm-square ﬁlters.
The round ﬁlters I tested are really too
small for this setup. While there was
only slight vignetting at the corners of
the frame, reﬂections from the ﬁlter
edges often marred images and complicated the process of ﬂat-ﬁeld calibrations. Experience has shown that
50-mm-square ﬁlters are better suited
for chips as large as the one in the
QHY600M.

A LL PHOTOS BY THE AU THOR

QHYCCD's
QHY600M Camera

http://www.qhyccd.com

Sky & Telescope - July 2020

Table of Contents for the Digital Edition of Sky & Telescope - July 2020