The QHY 268C - Photographic version contains the Sony IMX571, a high performance back illuminated cooled colour sensor with true 16-bit A/D. This translates to a dynamic range of 14 stops for vibrant and natural colours, even in faint or dark nebulae. The pixels have a size of 3.8 µm which is an excellent value for telescopes with different focal lengths.
Differently from the other cameras, QHY developed for the 268C three different capturing modes:
- #0 Photographic Mode: this is the standard mode that can be used for general astrophotography. The readout noise rapidly drops between 25 and 30 (2.5e- at gain 30) which is ideal for long focal length telescopes where a longer exposure time is required. The trade-off at gain 30 is a lower full well capacity at 30,000 e-. In fast telescopes (f/2.2 - f/4) the gain can be set to zero to use the maximum full well capacity (75,000 e-).
- #1 High Gain Mode: the readout noise is much lower at 3e- between gain 0 and 55. This mode is ideal for narrowband imaging where long exposures are generally required.
- #2 Extended Full Well: ideal for objects with bright stars or strong contrasts. The full well capacity is at the highest level along the entire gain range.
Unlike DSLR cameras, the QHY 268C offers true RAW image output that only records the signal without artefacts. Standard DSLR's have the RAW output option but the file is altered with noise reduction and hot pixel removal, undermining the maximum post processing capabilities and final quality of the image.
The camera has a two-stage TEC cooling system that brings the temperature of the sensor 35C° below ambient for low noise imaging, even in warm climates. The dark current at -20°C is only 0.0005 electron/pixels. In addition to thermoelectric cooling, QHYCCD employs a unique thermal noise control technology to reduce CMOS sensor noise to a very low value without affecting the integrity of the raw image. The QHYCCD proprietary technology produces a much better noise reduction than any other astronomy camera in the market. The QHY 268C employs a full anti-dew technology for both CMOS sensor cover glass and the optical window to avoid condensation or ice crystal in the camera.
The 1GB DDR II memory buffer facilitates the download of images to the computer, especially when USB traffic is high, the writing speed of your computer is slow or occupied with other processes.
In order to avoid halos around bright stars, the QHY 268C has an AR coated optical window on both sides rather than the common IR/UV cut coating. Also, the protection glass of the sensor is AR coated to maximize light transmission and minimize internal reflections. For a better RGB colour balance, it is recommended to use a UV/IR cut filter.
Every QHY 268C camera is carefully calibrated with a high-precision axis measurement device. Orthogonal placement of the sensor in the camera body is guaranteed to be flat to the image plane with a precision better than +/-20µm across the sensor, from edge to edge, so there is no need to adjust the camera tilt. This is an enormous advantage especially in fast telescopes such as F/2.8-F/4 astrographs which are very sensitive to tilted sensors.
The QHY 268C has zero amplifier glow no matter how long the exposure is.
|Sensor||Sony IMX571 back illuminated APS-C CMOS - COLOUR|
|Resolution||26 Megapixels 6280 x 4210|
|Pixel size||3.76 µm|
|Sensor size||23.61 mm x 15.83 mm (28.43 mm diagonal)|
|Read noise||0.7e- at high gain ; 3.5e- at lowest gain (2.7e- at high gain ; 5.5e- at lowest gain in extended full well mode)|
|Dark current||0.0005e-/pixel/sec @ -20C|
|Full well capacity||51,000 e- (more than 75ke- in extended full mode)|
|Bit rate||Native 16 bit ADC|
|Frame rate||6 fps at full resolution (16 bits)|
|Shutter type||Rolling shutter|
|Cooling||ΔT of 35°C Dual Stage TEC cooler|
|Memory buffer||1 GByte DDR3|
|Compatibility||Mac, Windows, Linux|
|Optical window||AR coated (both sides)|
|AR coating on sensor||YES|
|Ports||USB 3.0, CFW|
|Compatibility||Mac, Windows, Linux|
|Back focus||17.5 mm ±0.3mm|
|Connections||M54 x 0.75 female thread (embedded in camera dovetail adapter)|
|Dimensions||Ø 90 mm; ↨ 112.80 mm|
|Power supply||12V 3A (2.1×5.5 mm connector)|
- QHY 268C - Photographic Version
- USB 3.0 cable (1.5m)
- Screw jack power cable (5.5-2.1mm male jack with locking nut to 5.5-2.1mm female jack)
- Lighter plug adapter to 5.5-2.1mm power jack
- Desiccant Drying Tube (desiccant not included)
- Camera dovetail to M54 x 0.75 adapter with 3 thumb screws at 120°
- M54 x 0.75 to 2"adapter (2.5mm optical thickness, M48 x 0.75 internal thread for standard 2" filters)
- M48 adapter (optical thickness 5mm). It connects to the camera dovetail to M54x0.75 adapter using the provided screws
- Spacer rings (optical thickness of 0.5mm, 1mm, 2mm, 3mm, 4mm, 7mm). They connect to the camera dovetail to M54x0.75 adapter using the provided screws
- Bags of screws
- Australian plug power supply 240 to 12V 6A with 5.5-2.1 power jack (not in the photo below)