The QHY5V is a fairly recent offering and some of the software we were using to operate it was still at the beta stage.
Instructions were provided for downloading the driver and control software from the internet and, despite one small hiccup, we were up and running relatively quickly.
We used the latest beta version of the QHY5V’s control software, QGVideo32 during our tests.
The image sensor sits in the centre of a large T-threaded aperture, into which is screwed the supplied 1.25-inch eyepiece adaptor.
The sensor is located behind a small piece of glass.
This has a colour typical of an infrared blocking filter to prevent images being oversaturated by infrared light, which would result in a loss of definition.
Communication to the outside world is via a USB 2.0 port at the rear of the camera.
It can also be used as an autoguider via a second connection on the back.
Automatic control
The control software is well designed in some respects but less so in others.
A positive is the virtual, onscreen keyboard that allows you to type with your mouse when entering a capture file name.
There’s also a live histogram and an easy-to-use focus assist magnifier.
The drawbacks are the lack of frame rate and white balance controls.
The frame rates are determined by the camera itself, but it felt awkward not having the option to set them manually.
The camera has a top frame rate of 55fps.
However, turn on the colour option and this value drops.
If the object you’re imaging is reasonably small you can use one of the pre-defined regions of interest, which zone the sensor so you’re only using part of it.
This in turn means less data to transport and helps keep the frame rate higher.
Uncompressed images can be saved as individual FITS or BMP files, or alternatively saved to an AVI or SER file.
One highlight of the QHY5V is that it has a global shutter instead of a rolling one.
Global shutters, normally found on CCD sensors, make the entire sensor light sensitive at once.
Rolling shutters, on the other hand, enable the sensor one row at a time.
CMOS chips, as used in the QHY5V, can use either global or rolling shutters, but most use rolling.
The advantage of a global shutter is that it reduces artificial skewing of moving images and may help when imaging under jittery seeing.
Our colour Moon test failed to reveal much subtle lunar colour.
Mars and Jupiter showed the correct colouring but again, it appeared to be rather muted.
On the plus side, the camera showed good sensitivity and the noise levels were impressively low.
The QHY5V is probably best suited to intermediate astro imagers who like to fiddle with control settings.
There is some room for improvement with the control software, but the price is attractive – even more so when you consider that it can also be used as an autoguiding camera.
