- Included items
The QHY 268M contains the Sony IMX571, a high performance back illuminated cooled monochrome sensor with true 16-bit A/D. This translates to a dynamic range of 14 stops. The pixels have a size of 3.76 µm which is ideal for telescopes with different focal lengths.
From 2023 onwards, the QHY268 series has a redesigned front plate with shorter backfocus, 14.5mm compared to the previous 17.5mm. The QHY268M comes with all adapters necessary to reach 55-56mm backfocus, required by most correctors/reducers.
The 268M has four different capture modes:
- #0 Photographic Mode: this is the standard mode that can be used for general astrophotography. The readout noise rapidly drops between 25-30 (2.5e- at gain 30), ideal for longer exposures. 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 contrast. Full well capacity is the highest along the entire gain range.
- #3 2CMS mode: with correlated multiple sampling, readout noise can be better decreased. this mode can effectively raise the dynamic range under Extended Fullwell Mode.
Unlike DSLR cameras, the QHY 268M Pro offers true RAW image output that only records the signal without artefacts. Standard DSLR's have RAW output but the file is altered with noise reduction and hot pixel removal, undermining post processing capabilities and final image quality.
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, QHYCCD employs unique thermal noise control technology to reduce CMOS sensor noise to a very low value without affecting the integrity of the raw image. This proprietary technology produces much better noise reduction than any other astronomy camera on the market. The QHY 268M employs a full anti-dew technology for both CMOS sensor cover glass and the optical window to avoid condensation or ice crystals.
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.
To avoid halos around bright stars, the QHY 268M has an AR coated optical window on both sides rather than the common IR/UV cut coating. The glass of the sensor is AR coated to maximize light transmission and minimize internal reflections.
Every QHY 268M 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 268M has zero amplifier glow no matter how long the exposure is.
Adapters included with the camera necessary to reach a backfocus of 55-56mm.
|Sensor||Sony IMX571 back illuminated APS-C CMOS - MONOCHROME|
|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||1.1e- at high gain; 3.5e- at lowest gain (5.3e- at high gain ; 7.4e- 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 GB 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||14.5 mm|
|Connections||M54 x 0.75 female thread (embedded in camera dovetail adapter)|
|Dimensions||Ø 90 mm; ↨ 109.33 mm|
|Power supply||12V 3A (2.1×5.5 mm connector)|
- QHY 268M
- USB 3.0 cable (1.5m)
- Power cable (5.5-2.1mm male jack with locking nut to 5.5-2.1mm female jack)
- Australian power supply 240 to 12V 5A with 5.5-2.1 power jack
- Desiccant Drying Tube (desiccant not included)
- M54 x 0.75 to 2"adapter (2.5mm optical thickness, M48 x 0.75 internal thread for standard 2" filters)
- Spacers for QHY medium accessories - 10mm, 4mm, 3mm, 1mm
- Medium accessory to M48 adapter - 5mm
- Screws - 8x M3 8mm, 8x M3 23.5mm, 8x M3 27.5mm, 8x grub screws
I have a QHY 16200A but it can't be used on a RASA or Hyperstar so I bought the 268M. I did a somewhat limited comparison and I believe the 268M is better in some respects. My first light showed the abilities that the various modes can offer. I am happy with it.