Astronomical camera QHY5III178m

QHY5III178m is a special camera designed for shooting celestial objects. Unlike household cameras (for example, DSLRs), the data stream from the camera is recorded directly to the computer via a USB cable. In fact, this is a sophisticated web camera without a lens, with which a minute of uncompressed video takes up approximately 18 gigabytes. This imposes certain requirements on the computer in order to fully realize the capabilities of the camera, namely a high-speed USB 3.0 bus and a fast SSD drive.

QHY5III178m
QHY5III178m

The QHY5III178m camera is made in the “eyepiece” form factor with a 1.25-inch fit. The camera is light and compact, but its body is entirely metal with a finned radiator for better cooling. Monochrome sensor – Sony imx178, resolution 3056×2048 (approximately 6.3 megapixels). In addition, a 14-bit digital-to-analog converter is announced, a frame rate of 50 fps at full resolution and at 8 bits, a small pixel of 2.4 micrometers, a high-speed USB 3.0 bus, an autoguider port, and an “amp glow” reduction function. And it all works great 🙂

The kit includes a camera in a metal box, a cable, a restrictive ring, a USB 3.0 cable, a cable for autoguiding, as well as an adapter for a 1.25″ filter and, if I’m not mistaken, an adapter for C-mount lenses.

The main task for which I bought this camera in 2018 was photographing the Sun through the Coronado PST H-alpha 40 mm chromospheric telescope, since it is with the QHY5III178m:
a) it is possible to focus without problems with this telescope
b) the solar disk is completely placed in the field of view of the matrix , there is no need to shoot panoramas
c) the camera pixel is small enough (2.4 micrometers), which allows you to get rid of the Barlow lens when shooting the Sun.
d) the monochrome sensor is ideal for shooting the Sun in the H-alpha line, since there are no color microfilters in front of the photodetectors that reduce the resolution and creating a number of specific difficulties when processing the resulting material.
I was convinced that Coronado and the imx178 sensor were literally made for each other.

The Sun, November 4, 2023, 12:08
The Sun, November 4, 2023, 12:08

A separate bonus was that when working with a chromospheric telescope, so-called Newton’s rings (parasitic stripes) do not appear in the image, as, for example, with the AR0130CS sensor.

Newton's rings - shot with the ZWO ASI 120MM mini astronomical camera
Newton’s rings – shot with the ZWO ASI 120MM mini astronomical camera

The problem with the sensor is its “banding”, that is, when adding frames and adding sharpness, a repeating periodic horizontal structure becomes noticeable. Most likely, this is a feature of the sensor. I struggled with this problem for quite a long time, but I found an excellent solution that completely eliminates stripes in the image – FFT filtering using an additional program, for example, Fixel FFT (a free plugin for Adobe Photoshop).

Imx178 sensor banding. On the left is the original, on the right is after FFT filtering.
Imx178 sensor banding. On the left is the original, on the right is after FFT filtering.

When shooting with long exposures at high gain, the sensor’s own glow becomes noticeable. In the Sony imx178 sensor, three corners glow – lower left, upper right and lower right. The QHY5III178m camera has a function to suppress the sensor’s glow. Alas, it does not work perfectly – while the lower corners are well dimmed, the “light” on the top right remains virtually unchanged. However, subtracting the dark frame can almost completely eliminate this glow.

Amp glow reduction OFF
Amp glow reduction OFF
Amp glow reduction ON
Amp glow reduction ON

The QHY5III178m is one of my most used cameras. It is also perfect for shooting the Moon, planets, Venus (including in the ultraviolet range). The QHY5III178m also works great when shooting the Sun with the Baader Solar Contiuum green filter (540 nm), as well as the Antlia CaK calcium filter (near ultraviolet, 393.3 nm). Despite its initial lunar-planetary orientation, the camera is quite suitable for shooting deepsky objects with long exposures. Of course, the lack of active cooling and thermal stabilization affects the quality of image calibration, and a small pixel is very demanding both in terms of atmospheric stability and the quality of optics. And, of course, the QHY5III178m is a great guiding camera that allows you to significantly improve the accuracy of your mount even with a short-throw guide telescope.

Sun in continuum, March 2, 2022, 09:21
Sun in continuum, March 2, 2022, 09:21
Sunspot AR 3354 in the calcium line, July 1, 2023, 10:26
Sunspot AR 3354 in the calcium line, July 1, 2023, 10:26
Venus in ultraviolet light
Venus in ultraviolet light

The camera has a CS-mount thread for working with security lenses. This can be useful when shooting meteors, polar blues and other tasks where wide-angle shooting is required. For shooting meteors I use an inexpensive 2.5mm f1.2 lens. Well, another big plus is that the QHY5III178m camera in conjunction with a 25 mm CS-mount lens can be successfully used as a polar finder, since it works with the old version of the SharpCap program (2.9), which still has a free function for setting the polar axis.

Perseid meteor shower, August 13, 2019, 00:31-01:56.
Perseid meteor shower, August 13, 2019, 00:31-01:56.

There is also a color version of the camera – QHY5III178m. It is perfect for color photography of the Moon, planets, meteors, the Sun in the green region of the spectrum (Continuum), as well as for initial astrophotography of deep space objects.

You can order cameras on Aliexpress  – QHY5III178m (mono) и QHY5III178c (color).
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