MORAVIAN C4 16000C1 [MONO]

The Moravian C4 16000 Mono is a high performance cooled monochrome astronomy camera using the Gpixel GSENSE4040 CMOS sensor with a resolution of 4096 x 4096 pixels at 9μm. The sensor has a large area of 37 x 37mm, making it the ideal match for professional telescopes with large image circles such as those from Planewave Instruments.

The GSENSE4040 sensor is equipped with 12-bit ADCs (Analog to Digital Converters) only. However, there are two sets of ADCs inside the sensor, each capable to digitize the image with different gain — one set of ADCs uses low-gain channel, while the second set uses high-gain channel. Both 12-bit outputs of each ADC set can be combined to single image with true 16-bit dynamic range (such combined image is often called 16-bit HDR for High Dynamic Range).

C4-16000 with optional external filter wheel.

The mechanical design of this series inherits from earlier CCD-based G4-16000 cameras, which makes the C4 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 C4 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 control port for External filter wheel and Standard cooling.
• Camera with control port for External filter wheel and Enhanced cooling (11mm thicker due to larger heatsink).

C4 camera without filter wheel (left), with attached Medium External filter wheel and (middle) and with attached Large External filter wheel (right).

As opposed to smaller the C2 and C3 camera models, which offer an option to integrate filter wheel into camera shell, the large C4 camera sensors need square 50×50 mm filters, too big to fit into an Internal filter wheel. This means an External filter wheel is the only option for C4 cameras.

There are two sizes of the External filter wheels available:

• Medium “M” size wheel for 5 unmounted 50 × 50 mm square filters.
• Large “L” size wheel for 7 unmounted 50 × 50 mm square filters.

C4 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 C4 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.

C4 cameras do not offer the users to set gain, beside the two fixed low-gain and high-gain channels. 16-bit HDR image covers whole sensor dynamic range and manipulating with gain would bring no additional benefits.

Sensor linearity of GSENSE4040 sensor in HDR mode as found in the C4 16000 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 C4 series cameras can be used for advanced research and scientific applications like variable star photometry and exoplanet transits.

Combination of both low-gain and high-gain digitization channels into single 16-bit HDR image is designed to carefully preserve linear response to light. What's more, resulting 16-bit image does not combine full dynamic range of both low-gain and high-gain channels, but takes only the perfectly linear portions of both channels. So, the linearity of the resulting 16-bit image is perfect within the full dynamic range.

The regulated thermoelectric cooler is capable of cooling the CMOS sensor to approximately 30°C below ambient temperature on models with standard cooling. Models with Enhanced cooling can reach approximately 35°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.

The USB 3.0 port operates at 5 Gbps allowing for fast transfer rates. C4 cameras are equipped with onboard RAM, capable of holding several full-resolution frames. 

For more information on Moravian C4 cameras, please refer to the Moravian website.

Specifications

Mechanical diagram showing C4 camera with standard cooling on the left and enhanced cooling on the right. Detailed diagrams can be found on the Moravian website.