Starlight Xpress Trius-H814 CCD
A low-noise, high-resolution camera with extra USB connectivity built-in, the Nightscape 8300 is designed for imaging deep-sky objects at long exposures rather than the Moon or planets
The Trius-H814 is another in a long line of Starlight Xpress cameras that use Sony CCD sensors, chosen for their low levels of visual noise. All sensors generate noise, both from the process of reading the collected data and from thermal effects as the sensor warms up. Keeping the noise as low as possible produces cleaner images. This 9.2 megapixel camera is the largest of the Sony-equipped mono sensors in the Trius range. With pixels just 3.69x3.69µm in size, the Trius-H814 is ideal for use with short focal length telescopes – when used with our 500mm focal length refractor it produced a high sampling rate of 1.6 arcseconds per pixel.
Supplied in a custom-fitted case, the camera is finished in the standard Starlight Xpress gloss black. It has a low-profile, cylindrical body with integral cooling fins, making it suitable for use on a wide range of telescopes including Schmidt-Cassegrains with Fastar capability. Fastar is a device that converts a Schmidt-Cassegrain telescope with
a focal ratio of f/10 into a reflector with a much shorter focal length and a focal ratio of around f/2.
All the ports are neatly arranged on the rear panel where a pleasant surprise awaits – there are three USB Mini-B ports built-in. There is also a 12V input, an ST4 port and a USB in. A second 12V input can be found on the external fan, which is attached to the side of the camera. A 12V power supply and a ‘Y’ lead round off the package.
The tilt-adjustable front plate of the camera has a female T thread, allowing you to connect a filter wheel, focal reducer, field flattener or coma corrector, or attach a suitably equipped focus tube and a 2-inch nosepiece.
Set-up and shooting
We connected the camera to a Starlight Xpress mini filter wheel with a built-in off-axis guider that was attached to a William Optics Focal Reducer and Flattener IV. Various drivers are included on the supplied CD and these installed flawlessly on our Windows 7, 32-bit laptop. However, we had to start each viewing session by plugging in the camera first, then the filter wheel, or else we’d receive a ‘USB error’ message. Also included on the CD was a copy of Starlight Xpress’s SXV-Hmf USB camera control software although for our tests we used MaxIm DL.
Our imaging tests were carried out in mid to late August. With the set-point cooling adjusted to –20°C and an ambient temperature of 16.6°C, the camera took three minutes 55 seconds to reach target temperature, and then we were ready to image. Full-size image download time is around five seconds but when focusing, we used 2x2 binning, which made downloads even faster. Binning is a special mode in which several pixels are combined to produce a ‘superpixel’ that is very sensitive to light but reduces the image resolution.
The camera is designed for imaging deep-sky objects at long exposures rather than the Moon or planets. We chose two very different targets to test out the camera – a globular cluster, M13 in Hercules, and the Eastern Veil Nebula in Cygnus.
We found that dark frames (special calibration frames used to remove unwanted noise generated by the sensor) were not required and we were very impressed with the sensitivity of the camera. Despite poor sky conditions during our test period, we captured some satisfying images using both narrowband and LRGB filters.
The Trius-H814 is impressive and its high-resolution sensor neatly fills the gap between the popular Sony ICX285 and Kodak/Truesense KAF-8300 sensors. We’d recommend the Trius-H814 as an excellent choice for serious mono imaging.
The Trius range of cameras have a built-in triple USB hub so that it can be used to control three different devices as well as the camera.
One of the major problems encountered in modern deep-sky imaging is the number of cables required to operate and power the all pieces of equipment. Tangled cables are frustrating but with a mount control, camera control, autoguider and filter wheel all vying for USB sockets, you can also find yourself running out of ports on your computer before everything’s hooked up. Adding an external USB hub into the mix can often be problematic and we hear of connectivity problems using such items, which is why a built-in hub is such a bonus.
The Trius-H814 also comes with three short custom cables that connect to the camera at one end and have a female USB connection at the other to plug into your ancillary equipment. The result is a very neat installation.
ST4 port - Although the Trius-H814 is designed to be the main imaging camera, it can be used as an autoguiding camera using its built-in, industry-standard ST4 port. However, this opto-isolated (separate circuit) ST4 port can also be used to control your mount through your autoguider when using third-party software like MaxIm DL.
Two-stage Peltier cooling - A two-stage Peltier cooling system cools the sensor to as low as 40°C below the ambient temperature (a point referred to as the delta T). Set-point cooling selects the delta T and an onboard regulator maintains that temperature. Internal and external fans aid the cooling process.
Tiltable front - Lining the sensor up with your telescope’s optics is vital to avoid distorted stars on one side of the image. The Trius-H814 has a tiltable front plate that works in a similar way to the collimation bolts on the primary mirror of a reflector telescope to adjust its angle.
Camera control software - The camera control software supplied with the Trius-H814 is a little clunky in comparison with market leaders like MaxIm DL and AstroArt, but it functions well enough and will get you imaging quickly at no additional cost. A perfectly adequate autoguiding feature is included in the software.
Argon-filled sensor chamber - The CCD sensor is housed in a sealed chamber, which includes a fused-silica optical glass at the front that is multicoated to reduce reflections and increase light transmission. The sensor chamber is filled with dry argon gas to remove the risk of icing when the cooling system is in full operation.
This review originally appeared in the November 2013 issue of BBC Sky at Night Magazine. Prices correct at time of going to press.