Celestron Skyris 445C colour imaging camera

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Celestron Skyris 445C colour imaging camera

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David Hinds
01525 852696
This camera is designed for high-resolution imaging of the brighter planets, as well as areas of the Sun and Moon. USB 3.0 compatibility takes the Skyris 445C’s imaging ability to new heights

The Imaging Source has paired with Celestron to produce the Skyris 445C. This colour CCD camera, with USB 3.0 connectivity and a 1280x960 pixel Sony ICX445AQA chip at its heart, is designed for high-resolution imaging of the brighter planets of the Solar System, as well as areas of the Sun and Moon.
Digital video cameras are often used to produce high-resolution still images of our nearest neighbours. To get stills from a device like this, the recorded videos are split into individual frames and sorted in order of quality using stacking software such as RegiStax or DeepSkyStacker. The best frames are then aligned, combined and sharpened to produce a detailed image.
The number of frames you have to work with here depends on the frame rate, which is the number of consecutive images (or ‘frames’) that your device can capture per second. You can connect the Skyris 445C to your computer through either a USB 2.0 or a USB 3.0 port, but a USB 3.0 connection is better as it allows you to record at double the frame rate.
The camera can be operated using the supplied iCap 2.3 software. This program allows you to alter the exposure, gain and other settings, and start recording. It is best to record videos in the monochrome Y800 format, as this saves disk space and improves connection speed. You can convert the monochrome video to colour at a later date using software such as RegiStax. At night we found it best to set the record dialog box in the preview screen to RGB32 colour for easier focusing, then change this back to Y800 before recording.

In the field

On our newer Windows 7 laptop there were no real issues with running with either USB type, frame rate differences aside, but when using an older Windows XP laptop, which was USB2.0 only, iCap 2.3 crashed every time we tried to adjust the gain setting slider. As an alternative, we successfully used the camera with the latest version of freeware recording program FireCapture.

Our first imaging target was the first quarter Moon, captured using a 8.75-inch f/6 Newtonian reflector, 2x Barlow lens and an ultraviolet/infrared filter screwed onto the camera’s 1.25-inch adaptor. The Skyris 445C produced smooth images showing good detail over large regions, with the 1280x960 chip running at 30 frames per second (fps). We wanted to experiment by lowering the camera’s gamma setting for some of the higher-contrast lunar regions, but surprisingly the software has no slider to change this.

Jupiter was next on our list. To save hard disk space we set a reduced frame size of 640x480 pixels using the rather awkward ‘region of interest’ feature in iCap. The sensitivity of the camera was evident, however, and allowed short exposure times of 1/40th of a second. The final processed images showed good belt and spot details on the planet, but we had to stick with 15fps as higher speeds showed a ghosting artefact, visible as an arc on one side of the planet after processing. The artefact was absent at 15fps but got worse the higher we pushed the frame rate.

Our final target was the winter Sun, low in the south at midday, imaged with a white light filter over our scope’s aperture. The fully processed images revealed nicely detailed sunspots, solar granulation and bright faculae. Again we covered large areas of the disc with the big chip and, unlike Jupiter, recording at 30fps didn’t lead to any ghosting. Like the Moon, this high-contrast object didn’t need much processing, which suppressed the artefact.

If you are looking for a camera to have a go at producing your own detailed images of our near neighbours, you might well consider the Skyris 445C for its large colour chip and USB 3.0 connection.

The latest USB connectivity

The cameras in the Skyris range are some of the first astronomical video cameras to utilise USB 3.0 connectivity for improved data transfer rates. When using iCap to record videos in the highest quality uncompressed monochrome format (Y800), the large chip size limits the maximum video frame rate at USB 2.0 to 15fps. However, with a USB 3.0 connection the camera can run at a maximum of 30fps.

The advantage of this higher frame rate is that you can gather more video frames in a given time. When you come to process your videos, an increased number of frames helps to reduce signal noise in the stacked image, giving a smoother result. It also means that more detail can be pulled out when processing. You can still use the camera with USB 2.0 perfectly well – just not at the higher frame rates that USB 3.0 allows.

Colour chip - The Sony ICX445AQA CCD chip allows you to quickly record in full colour without having to capture separate red, green and blue videos through individual colour filters and recombining later on, as is the case with mono cameras. This speeds up the colour imaging process considerably and avoids the need to purchase a set of colour filters.

Body - The camera has a beautifully made and very neat aluminium housing, which is the about the size and weight of a medium-sized eyepiece. Heat dissipation fins machined into the exterior of the body keep the chip cool, helping to minimise noise.

Manual - The 15-page manual is worthy of comment as it 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 on digital video imaging.

1.25-inch adaptor - The kit comes complete with a 1.25-inch to C-mount adaptor, threaded for filters. This screws into the front of the camera so you can insert it into an eyepiece holder. Also included is a C-mount to CS-mount adaptor ring, should you wish to attach different video lenses directly.

USB 3.0 cable - Some video cameras come with connector leads that are impractically short. Not so the Skyris 445C: its USB 3.0 cable is a generous 3m. The plug is secured to the body of the camera by two thumbscrews, preventing accidental disconnection, and is backwards compatible with USB 2.0 sockets.

This review originally appeared in the March 2014 issue of BBC Sky at Night Magazine. Prices correct at time of going to press.

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