MORAVIAN C3 61000 [MONO]

 

The Moravian C3 61000 Mono is a high performance cooled monochrome astronomy camera using the Sony IMX455 CMOS sensor with a resolution of 9576 × 6388 pixels at 3.76μm. This latest generation of Sony back-illuminated sensors are natively 16-bit with exceptional sensitivity, full-well capacity, extremely low read noise and perfectly linear response to light.

 

The cooled C3 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 G3 Mark II cameras, which makes the C3 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 C3 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 multiple different variants:

• Camera with Internal filter wheel and Standard cooling.
• Camera with Internal filter wheel and Enhanced cooling (11mm thicker due to larger heatsink).
• Camera with control port for External filter wheel and Standard cooling. This model allows attachment of several variants of external filter wheels with various number of filter positions and sizes.
• Camera with control port for External filter wheel and Enhanced cooling. This model allows attachment of several variants of external filter wheels with various number of filter positions and sizes.

 

 

C3 Camera with internal filter wheel and standard/enhanced cooling (left), and with attached External filter wheel and standard/enhanced cooling (right).

 

C3 camera model with Internal filter wheel accepts two sizes of filters:

• Filter wheel with 5 positions for unmounted D50 mm (or 2”) filters or filters in 2” threaded cells.
• Filter wheel with 7 positions for unmounted D36 mm filters.

There are three sizes of the External filter wheels, capable to accept various sizes of filters, available for the C3 cameras:

• Small “S” size wheel for 10 unmounted filters D36 mm.
• Small “S” size wheel for 7 unmounted filters D50 mm or filters in 2” threaded cells.
• Small “S” size wheel for 5 unmounted square filters 50 × 50 mm.
• Middle “M” size wheel for 10 unmounted filters D36 mm.
• Middle “M” size wheel for 7 unmounted filters D50 mm or filters in 2” threaded cells.
• Middle “M” size wheel for 5 unmounted square filters 50 × 50 mm.
• Large “L” size wheel for 9 unmounted D50 mm or filters in 2” threaded cells.
• Large “L” size wheel for 7 unmounted square filters 50 × 50 mm.

Note: C3 cameras with full-frame sensors (such as the IMX455) cannot use 36mm filters due to the sensor being much larger than the clear aperture of these filters.

And third, there are two sizes of adjustable adapters, which can be used with C3 cameras:

• Small “S” adapters, compatible with C2 cameras, are used for e.g. M48 × 0.75 and M42 × 0.75 threaded adapters, Nikon bayonet adapter, 2” barrel adapter etc.
• Large “L” adapters, compatible with C4 cameras, intended for large diameter attachments between camera and telescope, e.g. M68 × 1 threaded adapter or G3-OAG, which is also equipped with M68 × 1 thread.

C3 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 C3 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.

Both IMX571 (used in C3 26000) and IMX455 (used in C3 61000) sensors are supplied in two variants:

• Consumer grade sensors found in the C3 26000 & C3 61000. The sensor manufacturer (Sony Semiconductor Solutions Corporation) limits their usage to consumer still cameras only with operation time max. 300 hours per year.
• Industrial grade sensors found in the C3 26000 PRO and C3 61000 PRO, intended for devices operating 24/7.

All sensor characteristics (resolution, dynamic range, …) are equal; sensors differ only in target applications and usage time. Cameras used for casual imaging (when weather permits) only rarely exceed 300 hours of observing time per year. Cameras permanently installed on observatories, utilizing every clear night and possibly located on mountain sites with lots of clear nights exceed the 300 hours/year within a couple of months.

C3 camera models with consumer-grade sensors include:

 

C3 camera models with industrial-grade sensors include:

 

 

Sensor linearity of IMX455 sensor as found in the C3 61000 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 C3 series cameras can be used for advanced research and scientific applications like variable star photometry and exoplanet transits.

The regulated thermoelectric cooler is capable of cooling the CMOS sensor to approximately 40°C below ambient temperature on models with standard cooling. Models with Enhanced cooling can reach 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 C3 cameras offer programmable gain from 0 to 36 dB, which translates to the output signal multiplication from 1× to 69×. Gain can be set with 0.1 dB step. 

The USB 3.0 port operates at 5 Gbps allowing for fast transfer rates. C3 cameras are equipped with onboard RAM, capable of holding several full-resolution frames. Additionally, these cameras can be ordered with a GPS receiver.

For more information on Moravian C3 cameras, please refer to the Moravian website.

Specifications

 

Sensor	CMOS Sony IMX455 monochrome
Resolution	61.17 megapixels 9576 × 6388
Pixel size	3.76 µm
Sensor size	36.01 × 24.02 mm (43.2 mm diagonal)
Quantum efficiency	~91%
Exposure range	From 156 μs
Read noise	1.39 e- @ 36 dB
Full well capacity	52,800 e- @ 0 dB
Bit rate	16-bit
Speed	0.44 s per frame
Shutter type	Rolling shutter with external mechanical shutter
Cooling	TEC-cooled
Memory buffer	Built-in RAM
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	154 mm × 154 mm × 65 mm (without internal filter wheel and standard cooling); 154 mm × 154 mm × 76 mm (without internal filter wheel and enhanced cooling)
Weight	1600 g (without internal filter wheel and standard cooling); 1800 g (without internal filter wheel and enhanced cooling)
Power supply	12V DC 5A 5.5 x 2.5 mm

 

Mechanical diagram showing C3 camera with standard cooling on the left and enhanced cooling on the right. Detailed diagrams can be found on the Moravian website.

 

Gallery

 

Eagle Nebula by Wolfgang Promper using Moravian C3-61000 and 600mm RC at f/4.5.

 

 

IC5148 by Wolfgang Promper using Moravian C3-61000 and 600mm RC at f/4.5.

 

 

Horsehead Nebula by Wolfgang Promper using Moravian C3-61000 and 600mm RC at f/4.5.