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| C1× cameras employ the same sensors like the C3 series — latest generation of Sony APS and Full-Frame (24 × 36 mm) CMOS sensors, offering exceptional quantum efficiency thanks to back-illuminated design and very low dark current. Despite relatively small pixels, full-well capacity exceeds 50 ke-, rivaling cameras with much greater pixels. Combined with full 16 bit digitization, perfectly linear response to light and exceptionally low read noise, these cameras are suitable for both aesthetic astro-photography as well as astronomical research. At the same time the C1× camera head is designed to be symmetrical, with as small front cross-section as possible. |
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The C1× family of cameras combine large APS and Full-Frame sized sensors, used in the C3 series, with a compact body of C1+ cameras. The front cross-section of the C1× camera head is the same like the C1+ one, only its body is a bit longer to accommodate more complex electronics as well as more powerful cooling (here originates the name of the entire series – C1 eXtended). Similarly to the C1+ line, also the C1× cameras lack mechanical shutter. Using of large sensors up to size 24 × 36 mm required also redesign of the telescope/lens adapters of the C1× line, the M42/M48 × 0.75 threads, used with C1+ camera adapters, are too small for such large sensors. So, the C1× adapters are equipped with new M56 × 1 thread. The front plate of the M56 × 1 adapter also contains four threaded holes, which makes it compatible with C3 camera body and thus the C1× can use the same External filter wheels and other accessories like the C3 line. Rich software and driver support allow usage of C1× camera without a necessity to invest into any 3rd party software package thanks to included free SIPS software package. However, ASCOM (for Windows) and INDI (for Linux) drivers and Linux driver libraries are shipped with the camera, provide the way to integrate C1× camera with broad variety of camera control programs. The C1× cameras are designed to work in cooperation with a host Personal Computer (PC). As opposite to digital still cameras, which are operated independently on the computer, the scientific cooled cameras usually require computer for operation control, image download, processing and storage etc. To operate the camera, you need a computer which:
C1× cameras are designed to be attached to host PC through very fast USB 3.0 port. While C1× cameras remain compatible with older (and slower) USB 2.0 interface, image download time is significantly longer. Alternatively, it is possible to use the Moravian Camera Ethernet Adapter device. This device can connect up to four Cx (and CCD based Gx) cameras of any type (not only C1×, but also C1, C2, C3 and C4) and offers 1 Gbps and 10/100 Mbps Ethernet interface for direct connection to the host PC. Because the PC then uses TCP/IP protocol to communicate with the cameras, it is possible to insert WiFi adapter or other networking device to the communication path. Hint: Please note that the USB standard allows usage of cable no longer than approx. 5 meters and USB 3.0 cables are even shorter to achieve very fast transfer speeds. On the other side, the TCP/IP communication protocol used to connect the camera over the Ethernet adapter is routable, so the distance between camera setup and the host PC is virtually unlimited. Download speed is naturally significantly slower when camera is attached over Ethernet adapter, especially when compared with direct USB 3 connection. The C1× cameras need an external power supply to operate. It is not possible to run the camera from the power lines provided by the USB cable, which is common for simple imagers. C1× cameras integrate highly efficient CMOS sensor cooling, shutter and possibly filter wheel, so their power requirements significantly exceed USB line power capabilities. On the other side separate power source eliminates problems with voltage drop on long USB cables or with drawing of laptop batteries etc. Also note the camera must be connected to some optical system (e.g. the telescope) to capture images. The camera is designed for long exposures, necessary to acquire the light from faint objects. If you plan to use the camera with the telescope, make sure the whole telescope/mount setup is capable to track the target object smoothly during long exposures. C1× Camera OverviewC1× camera head is designed to be as small and compact as a cooled camera with large sensor can be, and at the same time to be robust and resilient. C1× cameras are equipped with tiltable telescope interface and tripod mounting threaded holes. They are also compatible with external filter wheels designed for larger C2 and C3 cameras — camera head contains connector to control filter wheel. If the external filter wheel is used, the tiltable mechanism on the camera head is not accessible and tiltable adapters for external filter wheels are used instead. C1× cameras with external filter wheels are then compatible with vast range of other telescope and lens adapters including off-axis guider adapters etc. C1× camera head C1× camera head is designed to be easily used with a set of accessories to fulfill various observing needs. Camera adapter base back focal distance is 16.5 mm and can be used directly to attach the camera to the telescope focuser using the M56 × 1 thread. The M56 × 1 thread in the adapter base is also used to attach several adapters for specific mounting standards:
C1× camera with M48, Nikon and Canon lens adapters (left), and with Canon lens attached using bayonet EOS adapter (right) The adapter base is also equipped with four M3 threaded holes 44 mm apart. As the adapter base BFD is 16.5 mm — the same BFD like in the case of C2 and C3 cameras — there is a possibility to attach the External Filter Wheel to the C1× camera. Four sizes of the External filter wheels, capable to accept various sizes of filters, are available for the C1× cameras: Extra small “XS” size wheel for:
Small “S” size wheel for:
Medium “M” size wheel for:
Large “L” size wheel for:
Remark: The filter wheels with D36 mm filters can be used with C1× cameras equipped with APS size sensors only. Cameras with “Full-Frame” sensors (24 × 36 mm) cannot use such small filters. Note the “S” and “M” filter wheels are of very similar dimensions and hold the same number of the same filters. They differ in the adjustable adapter size only. C1× camera with “XS” and “S” sized External filter wheels If the External filter wheel is used, the tiltable base directly on the camera head stays inactive. Instead, another tiltable base, intended for C3 adapters, is manufactured directly on the External filter wheel front shell. So, if the External filter wheel is used, adapters for the M56 × 1 thread cannot be used. Instead, adapters designed for C3 cameras, must be used. There are two sizes of adjustable adapters available, depending of the External filter wheel size:
C1× Camera SystemSchematic diagram of C1× camera M56 × 1 tiltable adapter and telescope adapters using this standard Schematic diagram of C1× camera with the “S” size adapter system components Schematic diagram of C1× camera with the “L” size adapter system components Components of C1× Camera system include:
CMOS Sensor and Camera ElectronicsC1× cameras are equipped with Sony IMX rolling shutter back-illuminated CMOS detectors with 3.76 × 3.76 μm square pixels. Despite the relatively small pixel size, the full-well capacity over 50 ke- rivals the full-well capacity of competing CMOS sensors with much greater pixels and even exceeds the full-well capacity of CCD sensors with comparable pixel size. The used Sony sensors are equipped with 16-bit ADCs (Analog to Digital Converters). 16-bit digitization ensures enough resolution to completely cover the sensor exceptional dynamic range. Remark: While the used sensors offer also lower dynamic resolution (12 and 14 bit), C3 cameras do no utilize these modes. Astronomical images always use 2 bytes for a pixel, so lowering the dynamic resolution to 14 or 12 bits brings no advantage beside the slightly faster download. But cooled astronomical cameras are intended for very long exposures and a fraction of second saved on image download is negligible compared to huge benefits of 16-bit digitization. Both IMX571 (used in C1×26000) and IMX455 (used in C1×61000) sensors are supplied in two variants:
All sensor characteristics (resolution, dynamic range, …) are equal, sensors differ only in target applications and usage time. C3 is technically digital still camera, only specialized for astronomy. If it is also “consumer” camera strongly depends on users. Cameras used for causal imaging (when weather permits) only rarely exceeds 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. This is why the C1× cameras are offered in two variants:
C1× camera models with consumer-grade sensors include:
C1× camera models with industrial-grade sensors include:
Camera ElectronicsCMOS camera electronics primary role, beside the sensor initialization and some auxiliary functions, is to transfer data from the CMOS detector to the host PC for storage and processing. So, as opposite to CCD cameras, CMOS camera design cannot influence number of important camera features, like the dynamic range (bit-depth of the digitized pixels). Sensor linearityThe sensors used in the C1× cameras show very good linearity in response to light. This means the camera can be used for advanced research projects, like the photometry of variable stars and transiting exoplanets etc. Response of IMX455 sensor in 16-bit mode Download speedC1× cameras are equipped with on-board RAM, capable to hold several full-resolution frames. Downloading of the image to the host computer thus does not influence image digitization process, as the download only transfers already digitized images from camera memory. Time needed to digitize and download single full frame depends on USB connection type.
If only a sub-frame is read, time needed to digitize and download image is naturally lower. However, the download time is not cut proportionally to number of pixels thanks to some fixed overhead time, independent on the sub-frame dimensions.
Warning: Download times stated above are valid for cameras with firmware version 3.3 and later. Older firmware download times were approximately 30% longer. The driver is sometimes forced to read bigger portions of the sensor than the user defined because of a sub-frame position and dimension limitations imposed by the sensor hardware. Sometimes it is even necessary to read the whole sensor. Hint: It is recommended to click the Adjust Frame button in the Frame tab of the SIPS camera control tool. The selected frame dimensions are then adjusted according to sensor limitations. Adjusted frame is then read from the sensor, without a necessity to read a bigger portions or even whole sensor and crop image in firmware. C1× camera electronics supports in-camera 2 × 2 binning. If this binning mode is used, download speed increases because of less amount of data read from camera.
Warning: The in-camera binning is supported by firmware version 3.3 and later. Download speed when using the Moravian Camera Ethernet Adapter depends if the 100 Mbps or 1 Gbps Ethernet is used, if USB 2 or USB 3 is used to connect camera to Ethernet Adapter device, but also depends on the particular network utilization etc. When the camera is connected to the Ethernet Adapter using USB 3 and 1 Gbps Ethernet is directly connected to the host PC, download time of the C1×61000 full frame is approx. 2.5 s. Camera gainSensors used in C1× cameras offer programmable gain from 0 to 36 dB, which translates to the output signal multiplication from 1× to 63×. Remark: Note the C1× camera firmware supports only analog gain, which means real amplification of the signal prior to its digitization. The used sensors support also digital gain control, which is only numerical operation, bringing no real benefit for astronomical camera. Any such operation can be performed later during image processing if desired. Camera driver accepts gain as a number in the range 0 to 4030, which corresponds directly to sensor register value. This number does not represent gain in dB nor it is an exact gain multiply. However, the driver offers a function, which transforms the gain numerical value to gain expressed in dB as well as multiply. Some selected values are shown in the table:
Conversion factors and read noiseGenerally, many sensor characteristics depend on the used gain. Also, the used sensors employ two conversion paths. One path offers very low read noise, but cannot utilize full sensor dynamic range. Another conversion path offers maximum pixel capacity, but at the price of higher read noise. The cross point is set to gain 3× (approx. 10 dB), where the full well capacity drops from more than 50 ke- to ~17 ke-. The read noise then drops from ~3.2 e- RMS to ~1.5 e- RMS.
Sensor dynamic range, defined as full well capacity divided by read noise, is greatest when using gain 0, despite somewhat higher read noise:
Also, it is worth noting that in reality the noise floor is not always defined by read noise. Unless the camera is used with very narrow narrow-band filter (with FWHM only a few nm) and under very dark sky, the dominant source of noise is the sky glow. When the noise generated by sky glow exceeds approximately 4 e- RMS, extremely low read noise associated with gain set to 2750 or more is not utilized and dynamic range is unnecessarily limited by the lowered full well capacity. So, which gain settings is the best? This depends on the particular task.
Remark: Please note the values stated above are not published by sensor manufacturer, but determined from acquired images using the SIPS software package. Results may slightly vary depending on the test run, on the particular sensor and other factors (e.g. sensor temperature, sensor illumination conditions etc.), but also on the software used to determine these values, as the method is based on statistical analysis of sensor response to light. BinningThe camera driver and user’s applications offer wide variety of binning modes up to 4 × 4 pixels as well as all combinations of asymmetrical binning modes 1 × 2, 1 × 3, 1 × 4, 2 × 4 etc. To allow such flexibility, binning is performed only in the camera driver (software binning) and does not rely on the limited capabilities of the hardware binning. The negative side of software binning is the same download time like in the case of full-resolution 1 × 1 mode. For typical astronomy usage, the small fraction of second download time is irrelevant, but for applications sensitive to download time, the hardware 2 × 2 binning can be useful. Hardware binningC1× camera implements 2 × 2 binning mode in hardware in addition to normal 1 × 1 binning. Warning: Hardware binning is supported by camera firmware version 3.3 and later. The Windows SDK supports the hardware binning from version 4.11 and the SIPS software package from version 3.33. Hardware binning can be turned on and off using the parameter HWBinning in the 'cXusb.ini' configuration file, located in the same directory like the 'cXusb.dll' driver DLL file itself. [driver] HWBinning = true When the HWBinning parameter is set to true, the in-camera hardware binning is used. This mode brings faster download time, but also introduces several restrictions:
Remark: Despite the number of pixels in the 2 × 2 binned image is 1/4 of the full resolution image, the download time is not four-times lower. Adding vs. averaging pixelsThe traditional meaning of pixel binning implies adding of binned pixels. This originated in CCD sensors, where pixel charges were literally poured together within the sensor horizontal register and/or the output node. For CMOS sensors with full 16-bit dynamic resolution, the negative side of binning is limiting of the sensor dynamic range, as for instance only 1/4 of maximum charge in each of the 2 × 2 binned pixels leads to saturation of resulting pixel. CCDs eliminated this effect to some extend by increasing of the charge capacity of the output node and also by decreasing of the conversion factor in binned modes. But such possibilities are not available in CMOS detectors. Remark: CMOS sensors with less than 16-bit precision often just add binned pixels to fulfill the available resolution of 16-bit pixels. For instance, camera with 12-bit dynamic range can sum up to 4 × 4 pixels and still the resulting binned pixels will not overflow the 16-bit range. In theory, the resulting S/N ratio of binned pixel remains the same regardless if we add or average them. Let's take for example 2 × 2 binning:
As the C1× camera read noise in the maximum dynamic range (gain 0) is around 3.5 ADU, halving it in 2 × 2 binning mode still keeps the read noise above the lower 1-bit limit and at the same time binned pixel will not saturate. For higher binning modes, the noise approaches lower limit, but averaging pixels still protects from pixel saturation, which is more important than limiting of S/N. If we take into account that the image background noise is only rarely defined by the read noise of the sensor, as the noise caused by background sky glow is typically much higher, for 16-bit camera averaging pixels is definitely the better way to bin pixels compared to just adding them. This is why both software and hardware binning modes in the C1× cameras are by default implemented as averaging of pixels, not summing. However, both software and hardware binning modes can be switched to sum binned pixels instead of average them by the BinningSum parameter in the 'cXusb.ini' configuration file: [driver] BinningSum = true Let’s note there is one more possibility to bin pixels — in the application software. This time binning is not performed in camera hardware nor in the camera driver. Full resolution 1 × 1 image is downloaded from the camera and software itself then performs binning. The SIPS software adds pixels instead of averaging them, but at the same time SIPS converts images from 16-bit to 32-bit dynamic range. This means S/N of the binned images always increases, pixels never saturate and read noise newer approaches lower limit. The negative side of this option is two-time bigger images. Binning in photometrySaturated pixels within bright stars are no issue for aesthetic astro-photography, but photometry measurement is invalid if any pixel within the measured object reaches maximum value, because it is not possible to determine the amount of lost flux. Software performing photometry (e.g. the SIPS Photometry tool) should detect saturation value and invalidate entire photometric point not to introduce errors. But binning efficiently obliterates the fact that any of the binned pixels saturated (with the exception of all binned pixels reached saturation value). So, using of binning modes for research applications (photometry and astrometry) can lead to errors caused by lost flux in saturated pixels, which cannot be detected by the processing software due to binning. This is why the behavior of both software and hardware binning modes is user-configurable through the BinningSaturate parameter in the 'cXusb.ini' configuration file: [driver] BinningSaturate = true If the BinningSaturate parameter is set to true, resulting binned pixel is set to saturation value if any of the source pixels is saturated. For aesthetic astro-photography, keeping this parameter false could result into slightly better representation of bright star images, but for research applications, this parameter should always be set to true. Note the BinningSum and BinningSaturate parameters have any effect if the camera firmware version is 5.5 or later. Prior firmware versions just averaged binned pixels and the pixel saturation was not taken into account when hardware (in camera) binning was used. The earlier camera drivers, performing software binning, also used pixel averaging for binning, but handled the saturated pixels like the BinningSaturate parameter is true. Both above mentioned configuration parameters require at last the software/drivers version:
If the camera is used through the Moravian Camera Ethernet Adapter, it’s firmware must be updated to version 53 or newer. Exposure controlThe shortest theoretical exposure time of the C1× cameras depends on the used sensor type:
However, such short exposures have no practical application, especially in astronomy. The camera firmware rounds exposure time to a multiply of 100 μs intervals, so in reality the shortest exposure time of both camera models is 200 μs. Remark: Note the individual lines are not exposed at the same time, regardless of how short the exposure is, because of the rolling-shutter nature of the used sensors. The difference between the first and last line exposure start time is 0.15 s for the C1×26000 and 0.25 s for the C1×61000 camera. There is no theoretical limit on maximal exposure length, but in reality, the longest exposures are limited by saturation of the sensor either by incoming light or by dark current (see the following chapter about sensor cooling). Warning: Please note the short exposure timing is properly handled in the camera firmware version 6.7 and later. GPS exposure timingC1× cameras in the “T” version can be equipped with GPS receiver module (see the Optional Accessories chapter). The primary purpose of the GPS receiver is to provide precise times of exposures taken with the camera, which is required by applications dealing with astrometry of fast-moving objects (fast moving asteroids, satellites, and space debris on Earth orbit, …). The GPS module needs to locate at last 5 satellites to provide exposure timing information. Geographic data are available if only 3 satellites are visible, but especially the mean sea level precision suffers if less than 4 satellites are used. The camera SDK provides functions, allowing users to access precision exposure times as well as geographics location. The SIPS software package main imaging camera control tool window contains the “GPS” tab, which shows the state of the GPS fix. Determination of exact exposure time is quite complicated because of the rolling-shutter nature of the used sensors. Camera driver does all the calculations and returns the time of the start of exposure of the first line of the image. Still, users interested in precise exposure timing need to include several corrections into their calculations:
Warning: Please note the precise exposure timing is properly handled in the camera firmware version 7.10 and later. Always use the latest camera drivers (ASCOM or Camera SDK DLLs in Windows, INDI or libraries in Linux) available on the web. Also, always update the firmware in the Moravian Camera Ethernet Adapter if the camera is connected over Ethernet. Hardware trigger inputThe C1× cameras marked with the “T” suffix (the ones also compatible with GPS receiver modules) are equipped with a hardware trigger input port. The trigger input allows for external hardware to determine the exact time of exposure start. Remark: The external exposure triggering is supported by a variant of the StartExposure function named StartExposureTrigger, available for the user of the Camera SDK for Windows as well as Linux and Mac libraries and drivers. However, the SIPS software does not support triggered exposures. The hardware trigger input port is available on the back side of the C1× cameras. The port uses RJ11 four-pin connector. Pins 1 and 2 are connected and have a function of positive pole, pins 3 and 4 are connected to negative pole. The trigger is activated when an external hardware connects pins 1 and/or 2 with pins 3 and/or 4. The trigger input port is electrically isolated from the rest of the camera — power and USB grounds etc.
Cooling and power supplyRegulated thermoelectric cooling is capable to cool the CMOS sensor by approx. 35 °C below ambient temperature, depending on the camera type. The Peltier hot side is cooled by a fan. The sensor temperature is regulated with ±0.1 °C precision. High temperature drop and precision regulation ensure very low dark current for long exposures and allow proper image calibration. C1× air inlet with fan is on the bottom side of the camera head (left), air outlet vents are on the camera top side (right) The cooling performance depends on the environmental conditions and also on the power supply. If the power supply voltage drops below 12 V, the maximum temperature drop is lower.
Chip cooling specifications C1×61000 camera reaching -35 °C sensor temperature below ambient temperature Remark: Maximum temperature difference between the sensor and ambient air may be reached when the cooling runs at 100% power. However, temperature cannot be regulated in such case, camera has no room for keeping the sensor temperature when the ambient temperature rises. Typical temperature drop can be achieved with cooling running at approx. 90% power, which provides enough room for regulation. Overheating protectionThe C1× cameras are equipped with an overheating protection in their firmware. This protection is designed to prevent the Peltier hot side to reach temperatures above ~50°C sensor cooling is turned off to stop heat generation by the hot side of the Peltier TEC modules. Remark: Please note the overheating protection uses immediate temperature measurement, while the value of camera temperature, presented to the user, shows temperature averaged over a longer period. So, overheating protection may be engaged even before the displayed camera temperature reaches 50°C. Turning the overheating protection on results in a drop in cooling power, a decrease in the internal temperature of the camera and an increase in the temperature of the sensor. However, when the camera cools its internals down below the limit, cooling is turned on again. If the environment temperature is still high, camera internal temperature rises above the limit an overheating protection becomes active again. Remark: Please note this behavior may be mistaken for camera malfunction, but it is only necessary to operate the camera in the colder environment or to lower the desired sensor delta T to lower the amount of heat generated by the Peltier modules. The overheating protection is virtually never activated during real observing sessions, even if the environment temperature at night reaches 25°C or more, because camera internal temperature does not reach the limit. But if the camera is operated indoors in hot climate, overheating protection may be activated. Power supplyThe 12 V DC power supply enables camera operation from arbitrary power source including batteries, wall adapters etc. Universal 100-240 V AC/50-60 Hz, 60 W “brick” adapter is supplied with the camera. Although the camera power consumption does not exceed 50 W, the 60 W power supply ensures noise-free operation. Warning: The power connector on the camera head uses center-plus pin. Although all modern power supplies use this configuration, always make sure the polarity is correct if other than the supplied power source is used. Back side of the C1× camera with the 12 V DC power plug, as well as USB and External filter wheel connectors
Power supply specification Remark: Power consumption is measured on the 12 V DC side. Power consumption on the AC side of the supplied AC/DC power brick is higher. The camera contains its own power supplies inside, so it can be powered by unregulated 12 V DC power source — the input voltage can be anywhere between 10 and 14 V. However, some parameters (like cooling efficiency) can degrade if the supply drops below 12 V. C1× camera measures its input voltage and provides it to the control software. Input voltage is displayed in the Cooling tab of the Imaging Camera control tool in the SIPS program. This feature is important especially if you power the camera from batteries. 12 V DC/5 A power supply adapter for C1× camera Mechanical SpecificationsCompact and robust camera head measures only 78 × 78 × 108 mm (approx. 3.1 × 3.1 × 4.4 inches). The head is CNC-machined from high-quality aluminum and black anodized. The head itself contains USB-B (device) connector, connector for External Filter Wheel and 12 V DC power plug. The front side of the C1× camera body is not intended for direct attachment of the telescope/lens adapter. It is instead designed to accept tiltable adapter base, on with the telescope and lens adapters are mounted. The M56 × 1 thread and four M3 threaded holes creates the telescope/lens interface of C1× cameras
Mechanical specifications Remark: Back focus distance is measured from the sensor to the base on which adjustable adapters are mounted. Various adapters then provide back focal distance specific for the particular adapter type (e.g. Canon EOS bayonet adapter back focal distance is 44 mm). Stated back focal distance already calculates with glass permanently placed in the optical path (e.g. optical window covering the sensor cold chamber). C1× camera headC1× camera head with a tiltable adapter base with M56 × 1 inner thread and four M3 threaded holes front view C1× camera head with a tiltable adapter base side view C1× camera head with M42 × 0.75 or M48 × 0.75/2-inch adapter with 21.5 mm BFD C1× camera head with M42 × 0.75 or M48 × 0.75/2-inch adapter with 55 mm BFD C1× camera head with Canon EOS bayonet adapter for photographic lenses C1× camera head with Nikon bayonet adapter for photographic lenses Camera with the “XS” size External filter wheelC1× camera head with External filter wheel side view dimensions C1× camera head with External filter wheel bottom view dimensions The “S”, “M” and “L” sized External Filter Wheels diameter is greater (viz. External Filter Wheels), but the back focal distance of all external filter wheels is identical. Hint: The M48, Canon and Nikon adapters, intended for the M56 × 1 thread, cannot be used with the External filter wheels. However, the External filter wheel is equipped with adapter base for C2 and C3 adapters and thus all adapters, designed for these cameras, can be used with C1× and External filter wheel. Optional accessoriesVarious accessories are offered with C1× cameras to enhance functionality and help camera integration into imaging setups. Telescope adaptersVarious telescope and lens adapters for the C1× cameras are offered. Users can choose any adapter according to their needs and other adapters can be ordered separately. C1× camera with M48×0.75 threaded adapter (left) and Canon EOS bayonet adapter (right) There are two means of connection between the tiltable adapter base on the C1 camera head and actual adapter:
Canon (left), Nikon (middle) and M48 × 0.75 adapters If the External filter wheel is attached to the C1× base, telescope/lens adapters are attached to the External filter wheel. In such case adapters compatible with the C2 or C3 cameras are used. There are two sizes of the adjustable adapter base, depending on the size of the External filter wheel used:
Small “S” size adapters:
Large “L” size adapters:
All telescope/lens adapters of the C1× series of cameras can be slightly tilted. This feature is introduced to compensate for possible misalignments in perpendicularity of the telescope optical axis and sensor plane. Adapters are attached using three “pulling” screws. As the adapter tilt is adjustable, another three “pushing” screws are intended to fix the adapter after some pulling screw is released to adjust the tilt. Adjusting the telescope adapter tilt — releasing of the “pushing” screw (left) and adjusting of the "pulling" screw Because the necessity to adjust two screws (one pushing, one pulling) at once is inconvenient, the adapter tilting mechanism is also equipped with ring-shaped spring, which pushes the adapter out of the camera body. This means the pushing screws can be released and still slight releasing of the pulling screw means the distance between the adapter and the camera body increases. The spring is designed to be strong enough to push the camera head from the adapter (fixed on the telescope) regardless of the camera orientation. Only after the proper tilt is reached, the pushing screws should be slightly tightened to fix the adapter in the desired angle relative to camera head. This ensures long-time stability of the adjusted adapter. If the External filter wheel is used, the adjustment screws on the camera body are not accessible and they are not used to adjust the tilt. Instead, an adjustable adapter base on the External filter wheel is used to correct possible tilt. External filter wheels are already designed for adjustable telescope adapters compatible with C3 cameras Off-Axis Guider adapterThe Off-Axis Guider adapter (OAG) can be used with the C1× camera only if the External filter Wheel is used. Then the C3-OAG with M68 × 1 thread can be attached to the “M” or “L” External filter wheel. Remark: Technically also the C2-OAG with M48 × 0.75 thread can be attached to the “XS” and “S” External filter wheels, but C2-OAG mirror is positioned too close to the optical axis with respect to relatively small sensors of the C1+/C2 camera lines. So, the C2-OAG mirror would partially shadow large sensors use in the C1× cameras. OAG contains flat mirror, tilted by 45° to the optical axis. This mirror reflects part of the incoming light into guider camera port. The mirror is located far enough from the optical axis not to block light coming to the main camera sensor, so the optics must be capable to create large enough field of view to illuminate the tilted mirror. The C3-OAG is manufactured with M68 × 1 thread with the back focal distance 61.5 mm. Position of the OAG reflection mirror relative to optical axis The OAG guider port is compatible with C0 and C1 cameras with CS-mount adapter. It is necessary to replace the CS/1.25” adapter with short, 10 mm variant in the case of C1 cameras. Because C1 cameras follow CS-mount standard, (BFD 12.5 mm), any camera following this standard with 10 mm long 1.25” adapter should work properly with the C3-OAG. GPS receiver moduleThe C1× variants marked with suffix “T” (for Trigger Input) can be equipped with an optional GPS receiver module, which allows very precise timing of the exposure times. Geographic location data are also available to the control software through specific commands. The used GPS receiver is compatible with GPS, GLONASS, Galileo and BeiDou satellites. The GPS receiver can be attached to the side of the camera head. If the GPS module is removed, the GPS port is covered with a flat black cover. Warning: Please note only camera variants marked with “T” suffix are compatible with GPS modules. So, it is necessary to choose GPS-ready variant upon camera ordering. Attaching camera head to telescope mountC1× cameras are equipped with a “tripod” 0.250-20UNC thread, as well as four metric M4 threaded holes, on the bottom side of the camera head. Threaded mounting holes on the C1× camera head bottom side (left), 1.75" bar for standard telescope mounts (right) These threaded holes can be used to attach 1.75 inch “dovetail bar” (Vixen standard). It is then possible to attach the camera head, e.g. equipped with photographic lens, directly to various telescope mounts supporting this standard. Tool-less desiccant containersC1× cameras employ the same desiccant container like the larger Enhanced cooling variants of the C3 and C4 cameras. The whole container can be unscrewed, so it is possible to exchange silica-gel without the necessity to remove the camera from the telescope. The whole desiccant container can be baked to dry the silica-gel inside or its content can be poured out after unscrewing the perforated internal cap and baked separately Remark: This is why the container itself does not contain any sealing, which could be damaged by high temperature in the oven. The sealing remains on the sensor cold chamber instead. Container shipped with the camera by default does not exceed the camera head outline. It is equipped with a slot for tool (or for just a coin), allowing releasing and also tightening of the container. This design also allows usage of some optional parts:
Comparison of the standard and tool-less container (left), optional cap, standard and tool-less variant of the container |
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