The Celestron Skyris 132M Solar System Imager is the latest high-speed digital video camera from the Celestron and The Imaging Source.
Devices such as this are capable of recording a stream of frames, the best of which can then be stacked and sharpened to produce an image largely free from the blurring effect of our atmosphere.
In common with the Celestron NexImage Burst camera, the Skyris 132M contains an Aptina ARO132 CMOS chip with a generous 1,280×960 pixels.
However it has a different housing and also supports USB 3.0, enabling faster download speeds and allowing more frames to be gathered in a given time.
The 132M is a monochrome camera; a colour variant, the 132C, is available for the same price.
That means if you want to capture colour shots of the planets you’ll need to take separate red, green and blue exposures and combine them, and to achieve that you need to add a filter wheel to the front of the camera – the end result is much heavier than a one-shot colour device.
The camera can be operated using The Imaging Source’s iCap camera control program, which is supplied on a CD in the box, or the freeware program FireCapture.
After installing the camera driver from the CD we used both programs to record video on laptops running Windows XP and Windows 7.
Capture speeds were hampered somewhat by their slow hard drives, but shorter runs were faster in FireCapture with its frame buffering feature.
We checked on Celestron’s website and the drivers on the disc were actually more recent versions than those available online.
Getting to grips with gain
We tested the camera on the almost full Moon, using it in conjunction with an 8.75-inch Newtonian and fitted with a 742nm infrared filter in front of the camera nosepiece to reduce the blurring effects of the atmosphere.
The big chip allowed us to capture a large area of the Moon at high resolution, while the high sensitivity allowed us to use a low gain to reduce noise but still use short exposures at the longer wavelengths we were imaging in, where a CMOS chip’s sensitivity falls off.
For the Sun we used a similar set-up, swapping the infrared filter in front of the camera and a white light solar filter in front of the telescope.
With the high surface brightness and high sensitivity of the camera we could drop the gain to the minimum to reduce noise.
We managed to capture a nicely detailed sunspot at the edge of the solar disc, as well as faculae and solar granulation.
Jupiter, sitting high overhead, was a bit more troublesome.
At a gain setting of 60 per cent or less the planet suffered from edge-ringing artefacts due to the higher levels of image processing required to bring out detail on the planet’s disc.
To combat this we had to run the camera at a higher gain, but this led to the image being quite noisy. On warmer nights a vertical noise pattern across the field was faintly visible.
The chip also has no protective window and small dust particles often settled on it while in use; these had to be blown off.
Eventually, by using a gain of 75 per cent on a steady night and an 18-inch telescope, we gathered enough red, green and blue frames to later make an RGB image showing detail within the Great Red Spot and a wealth of other fine features.
Quicker capture rates
The Skyris 132M has USB 3.0 connectivity, allowing faster video data transfer rates when imaging.
This allows you to gather more frames in a short space of time, provided the object is bright and you don’t need exposure times longer than the frame time.
More frames means less noise and a higher number of really good frames available for stacking, leading to better final images.
With a computer with a fast hard drive and USB 3.0 capability, we found that with a bright object we could achieve frame rates of 60 frames per second (fps) at full frame – twice the maximum speed achievable with USB 2.0.
The camera also has hardware selectable ‘region of interest’ capability enabling reduced frame sizes but even faster transfers of over 400fps.
On an older USB 3.0 laptop we could reach these speeds for short periods using the frame-buffering capability that FireCapture allows, but a more modern laptop should capture directly to the hard drive at this speed without buffering.
The camera body is small, lightweight and has heat fins to help keep the camera cool and minimise noise.
However a tripod mounting screw hole would have been useful so you could use the camera off the scope with a suitable lens.
The 15-page manual is particularly well laid out and clear.
It covers system requirements, driver and software installation, how to use the camera to capture videos and how to process them in RegiStax.
There are also some useful general tips.
The Skyris 132M is one of a growing number of Solar System cameras that use a CMOS chip rather than the more traditional CCD.
Recent advances mean these chips are now often cheaper, create less noise and offer higher sensitivity than CCD chips.
The Skyris 132M comes with a C-mount to 1.25-inch adaptor, which screws to the front of the camera and is threaded for filters for RGB imaging.
The distance to the chip from the front of the camera without the 5mm spacer supplied is the standard CS-mount distance of 12.5mm.
USB 3.0 cable
Unlike some video cameras that come with leads that are impractically short, the Skyris 132M is packaged with a 3m USB 3.0 cable.
The plug is secured to the body of the camera with two thumbscrews, preventing accidental disconnection.
The cable is backwards compatible with USB 2.0 sockets.
This review originally appeared in the June 2015 issue of BBC Sky at Night Magazine.