MORAVIAN C2 3000C [COLOUR]

 

The Moravian C2 3000 Colour is a high performance cooled colour astronomy camera using the Sony IMX252 CMOS sensor with a resolution of 2064 x 1544 pixels at 3.45μm. All C2 series cameras feature a mechanical shutter.

 

The cooled C2 series CMOS cameras were developed for imaging under extremely low-light conditions in astronomy, microscopy and similar areas. Mechanical design of this series inherits from earlier CCD-based G2 Mark II cameras, which makes the C2 series fully compatible with vast range of telescope adapters, off-axis guider adapters, internal or external filter wheels, Camera Ethernet adapters, guiding cameras etc.

The C2 camera head is designed to be easily used with a set of accessories to fulfill various observing needs. The camera head itself is manufactured in two different variants:

• Camera with Internal filter wheel.
• Camera with control port for External filter wheel. This model allows attachment of several variants of external filter wheels with various number of filter positions and sizes.

 

 

C2 Camera without filter wheel (left), with Internal filter wheel (middle) and with attached External filter wheel (right).

 

C2 camera model with Internal filter wheel accepts two sizes of filters:

• Filter wheel with 5 positions for unmounted D31 mm filters or filters in 1.25” threaded cells.
• Filter wheel with 6 positions for unmounted D27 mm (or 1”) filters.

There are two sizes of the External filter wheels, each capable to accept multiple sizes of filters, available for the C2 cameras:

• Extra small “XS” size wheel for 8 unmounted filters D31 mm or filters in 1.25” threaded cells.
• Extra small “XS” size wheel for 7 unmounted filters D36 mm.
• Small “S” size wheel for 12 unmounted filters D31 mm or filters in 1.25” threaded cells.
• Small “S” size wheel for 10 unmounted filters D36 mm.
• Small “S” size wheel for 7 unmounted D50 mm or 2" filter or filters in 2” threaded cells.

C2 cameras are equipped with a mechanical shutter, which is an important feature allowing unattended observations (fully robotic or just remote setups). Without a mechanical shutter, it is not possible to automatically acquire dark frames, necessary for proper image calibration etc.

The mechanical shutter in the C2 cameras is designed to be as reliable as possible, so the number of open/close cycles is virtually unlimited, because there are no surfaces rubbing against each other. The price for high reliability is slow shutter motion. Luckily, mechanical shuttering is not necessary for exposure control, only for taking dark frames and possibly bias frames — all used CMOS sensors are equipped with electronic shuttering.

C2 series cameras are equipped with either global shutter or rolling shutter CMOS sensors (in the case of the IMX533 version).

Three lines of global shutter C2 cameras are available depending on the available dynamic range (bit-depth of the digitized pixels) and pixel size:

• C2 cameras with Sony IMX sensors with 3.45 × 3.45 μm pixels, supporting 8- and 12-bit digitization. Because every 12-bit pixel occupies two bytes when transferred to host PC, 12-bit image download time is longer compared to 8-bit image. Maximal FPS in 8-bit mode is then significantly higher.
• C2 cameras with Sony IMX sensors with 3.45 × 3.45 μm pixels, supporting 12-bit digitization only. As the 12-bit read mode is always used for long-exposure applications (astronomical photography, scientific research) either way, lower theoretical download time in 8-bit mode brings no limitations for real-world scenarios. All other parameters being same (sensor size, resolution, pixels size, noise, …), so the lower price of these cameras may be then very attractive.
• C2 cameras with Sony IMX sensors with 4.50 × 4.50 μm pixels and 12-bit digitization only. Larger pixels mean higher dynamic range (more electrons can be stored in each pixel before it saturates), but also higher read noise. Still the theoretical S/N is almost the same because of higher signal camera can accumulate. This camera is more suitable for longer focal length telescopes, where small pixels provide oversampled images, and also for research applications, where dynamic range is important.

 

 

Sensor linearity of IMX265 sensor as found in the C2/C1 3000 camera.

 

The CMOS sensors found in these cameras have a response to light that is linear very close to the saturation point. This means the C2 series cameras can be used for entry-level research and scientific applications like variable star photometry.

The regulated thermoelectric cooler is capable of cooling the CMOS sensor to approximately 45°C below ambient temperature. The sensor temperature is regulated with ±0.1 °C precision. High temperature reduction and precision regulation ensure very low dark current for long exposures and allow proper image calibration. Two temperature sensors are built-in to the camera - one measuring the sensor package temperature and one measuring the temperature inside the casing.

Sensors used in C2 cameras offer programmable gain from 0 to 24 dB, which translates to the output signal multiplication from 1× to 15.9×. Gain can be set with 0.1 dB step.

The USB 3.0 port operates at 5 Gbps allowing for fast transfer rates. C2 cameras with the "T" suffix include a hardware trigger input port for use with the optional GPS receiver module.

For more information on Moravian C2 cameras, please refer to the Moravian website.

Specifications

 

Sensor	CMOS Sony IMX252 colour
Resolution	3.1 megapixels 2064 x 1544
Pixel size	3.45 µm
Sensor size	7.1 mm x 5.3 mm (8.9 mm diagonal)
Quantum efficiency	~61%
Exposure range	From 125 μs
Read noise	2.0 e- @ 24 dB
Full well capacity	11,000 e- @ 0 dB
Bit rate	12-bit / 8-bit (depending on model)
Speed	~263 MPx/s digitization speed (8-bit fast mode)
Shutter type	Global shutter with external mechanical shutter
Cooling	TEC-cooled
Memory buffer	TBD
ROI	Supported
Compatibility	Windows, Mac, Linux
Protecting window	TBD
Ports	USB 3.0, Trig-in (for "T" version), EFW
Back focus	33.5 mm from sensor to adapter mounting flange
Connections	Varies - many different adapters available
Dimensions	114 mm × 114 mm × 77.5 mm (with internal filter wheel); 114 mm × 114 mm × 65 mm (without filter wheel)
Weight	1000 g (without filter wheel)
Power supply	12V DC 5A 5.5 x 2.5 mm

 

 

Mechanical diagram showing C2 camera with integrated filter wheel on the left and External Filter Wheel on the right. Detailed diagrams can be found on the Moravian website.

 

Gallery

 

M51 by Martin Myslivec using Moravian C2-9000 and 400mm f/2.9 astrograph.

 

 

M82 by Martin Myslivec using Moravian C2-12000 and 300mm f/3.8 astrograph.