Supplier: 365 Astronomy
Telephone: 020 3384 5187
On the outside the ASI294MC Pro colour cooled camera doesn’t appear to bring much new to the company’s range, with its familiar styling, USB 2 hub and high-speed USB 3 port.
But it’s on the inside that the camera starts to become much more interesting and exciting.
This is the first camera in the world to boast Sony’s new IMX294 CJK back-illuminated 3/4-inch sensor, with a diagonal size of 23.2mm and approximately 11.71MP.
Being part of the Pro range, the camera comes with 256MB DDR3 (double data rate type three) memory installed and a two-stage TEC cooling system that will cool it to between –35°C and –45°C below ambient temperature.
You’ll need a good power supply for the camera to reach this range, though, because a power supply unit under 3A can cause software to disconnect when you’re capturing images.
HGC is a new feature with this camera and stands for high gain conversion.
It switches on automatically when the camera’s gain is raised above 120.
This reduces read noise to a lower level at higher gain without a loss to the dynamic range.
ZWO claims this means the camera can capture 4K images, although in our experience 4K would probably be more suited to industrial applications than astronomy.
While we had a lot of warm weather over the review period, they weren’t the clearest seeing conditions, with lots of high cloud.
As the Moon was also bright we set up for some imaging in the early evening and it soon became apparent that we needed to play with the camera’s settings.
The initial onscreen view was very blue.
On checking, the blue level was starting at 90 instead of around 55.
We contacted the manufacturer and they were helpful in solving the problem.
It seems it was a software glitch.
Picking out the finer details
Once sorted, the camera produced a fine image on screen and capturing was very easy using the SER file capture mode.
While not the fastest camera in full resolution we only needed to capture around 200 frames and stack 50 to produce a decent image of the Moon.
Switching over to planetary capture a few nights later, the camera performed well under the poor conditions and low views we had this season.
Running in Region Of Interest (ROI) mode on Saturn we were able to capture some good detail with the use of an atmospheric dispersion corrector on a 4-inch, f/11 telescope.
The next target was Mars and, to be honest, we were not expecting to capture any surface detail because of the dust storm that was enveloping the planet.
Using the same telescope with the addition of a 4x Powermate we set ROI capture to 640×480.In this mode the camera was recording at around 100fps.
The results were especially impressive because we processed images from a few cameras that week, and the ASI294MC was the only one that picked up any surface detail on Mars.
On the next clear night, we used the camera coupled with a 2.5-inch quad refractor to image M31, the Andromeda Galaxy, and look at some live views of targets.
To achieve this, we set the camera up in USB 2 mode with a 7m USB extension lead.
The camera was very stable, dropping no frames in the capture software, while using a short capture time of 60 seconds meant we didn’t need to autoguide.
The camera is great for live capture and live stacking of objects, and it was a pleasure to watch a comet cross the screen in real time.
This would be ideal for outreach events for showing objects to the public, or for live stacking in capture software.
The ZWO 294 MC Pro camera really has something for everyone and with CMOS sensor boundaries being pushed with each new model of camera that comes out, it makes us wonder what new developments will be coming next.
Outstanding feature: the sensor
The IMX294 is a 4/3-inch, back-illuminated sensor with a diagonal size of 23.2mm and a resolution of 4,144×2,822.
In 14-bit mode the camera will run at around 16fps at full resolution and up to 25fps in 10-bit mode.
When the camera is used in ROI mode, the frame rate can run up to 120fps.
HGC (high gain conversion) mode switches on when the gain goes over 120 and this helps to keep the dynamic range constant.
The 63700e full well capacity (the amount of charge an individual pixel can hold before saturating) is three times that of an ASI 1600 camera’s, making it very sensitive and ideal for electronically assisted astronomy (EAA), live stacking and live displays at outreach events.
What this really helps with is cutting down the saturation of stars even when capturing long exposures, which has been a problem with some CMOS sensors in the past.
The ASI294MC has a UV/IR cut-off filter as it has a colour sensor.
The range for this is between 400-700nm and it helps protect images from stray signals when the camera is used in planetary mode.
The sensor chamber is designed as a sealed unit, so it is not advisable to remove the optical window with this design of camera.
DDR memory buffer
Included with the camera is a 256MB DDR3 memory buffer, which helps with reliably transferring data.
DDR3 has the added benefit of reducing amp glow caused by slow transfer speeds when the camera is used with a USB 2 port.
It also helps with a stable connection when running the camera on extended USB leads.
The ZWO ASI294MC comes with an extensive array of accessories making it easy for the user to connect to other equipment.
This includes a 1.8m USB 3 cable, a CD-ROM with two software applications (FireCapture and SharpCap), as well as a 1.25-inch nose piece, cover and adaptor.
There is also a padded bag for camera protection.
USB 3 port & USB 2 hub
The camera has a USB 3 port enabling it to support between 16-19fps (dependent on mode) at full resolutions.
The ASI294MC also sports a USB 2 hub allowing the user to connect an array of accessories, such as filter wheels and guide cameras.
The camera comes supplied with an additional two 0.5m USB 2 cables.
The Pro version of the ZWO ASI294MC has a built-in two-stage TEC cooler which allows temperatures to be regulated within the capture software to –35° to –45°C below ambient.
The cooler requires a 12V power supply, which is not currently supplied and is an extra add-on item.
This review originally appeared in the October 2018 issue of BBC Sky at Night Magazine