QHYCCD QHY461PH Monochrome Medium Format Cooled Camera

The 102 MP Sony IMX461: A Medium Format BSI Sensor

At the core of the QHY461PH is the Sony IMX461, a back-illuminated (BSI) CMOS sensor with an effective resolution of 11664 x 8748 pixels. This 102-megapixel array, combined with a 3.76µm pixel size, provides an ideal balance of resolution and sampling for modern high-quality refractors and reflectors. The medium format 44mm x 33mm sensor (55mm diagonal) allows you to frame enormous celestial targets in a single shot.

The BSI structure places the sensor's wiring below the photosensitive layer, maximizing the light-gathering area of each pixel for higher quantum efficiency across the visible spectrum. For imagers using larger telescopes, 2x2 binning creates 7.5µm effective pixels and still delivers a 25-megapixel image, offering enhanced sensitivity and higher full well capacity while maintaining a resolution far greater than previous-generation CCDs.

Native 16-bit A/D and Multiple Readout Modes

The IMX461 sensor features on-chip, native 16-bit analog-to-digital conversion, capturing image data with 65,536 distinct grey levels. This high bit depth provides the sample resolution needed to record subtle variations in nebulosity and galaxy structure without posterization, a critical advantage over 12-bit or 14-bit sensors. This architecture, where each column of pixels has its own A/D converter, also contributes to the camera's remarkably low read noise of 1e- to 3.7e-.

The QHY461PH offers multiple user-selectable readout modes to optimize performance for different targets. You can choose between Standard Mode with a 50ke- full well capacity, or Extended Full Well Mode, which boosts capacity to 80ke- for capturing bright stars in dense fields without saturation. These capacities increase dramatically with binning, reaching up to 720ke- in 3x3 Extended Mode, giving you immense flexibility for both broadband and narrowband imaging.

Advanced Noise Control: -35°C Cooling and 0.003e- Dark Current

A clean signal is paramount for deep-sky imaging, and the QHY461PH employs a multi-faceted approach to noise suppression. A powerful dual-stage thermoelectric cooling (TEC) system actively reduces the sensor temperature to -35°C below ambient for long exposures, drastically lowering thermal noise. This results in an exceptionally low dark current of just 0.003 e-/pixel/s at a sensor temperature of -20°C.

QHYCCD's design completely eliminates amplifier glow, ensuring that no part of the frame is contaminated by this common source of calibration error. Furthermore, the camera incorporates proprietary technology to suppress time-variant thermal noise, a characteristic of some BSI sensors, resulting in cleaner, more consistent raw frames that stack beautifully.

1GB DDR3 Buffer and USB 3.0 Data Path

Managing the massive 102-megapixel data stream requires a robust data path. The QHY461PH is equipped with a 1GB DDR3 image buffer to keep image transfer from the camera to your computer stable and free of dropped frames, even when the computer is briefly busy.

The USB 3.0 interface enables a full-resolution 16-bit frame download at 1.3 FPS. For fine-tuning, the camera's drivers allow you to adjust the USB traffic setting. This feature can optimize the sensor's driver frequency to mitigate periodic horizontal banding that can sometimes appear, ensuring the cleanest possible raw data for processing.

Observatory-Ready Design: Dew Control, Power Management, and 32.5mm Back Focus

The QHY461PH is engineered for reliability in the field. The optical window has a built-in dew heater, a humidity sensor is built in, and QHYCCD's silicone gel tube socket design keeps the sensor chamber dry. A desiccant tube is included in the box.

For remote operation, the camera features robust power management. It requires a stable 12V supply and has Under Voltage Lockout (UVLO) protection, which warns you if the voltage drops below 11V. You can also reboot the camera by simply cycling the 12V power, eliminating the need to physically reconnect the USB cable. The back focal length is 32.5mm (±0.2), the figure to plan your filter wheel, off-axis guider and spacers around.

The Imaging Train Solution: QHY461PH, CFW3XL, and OAG-L Pro Combo

To fully utilize the QHY461PH's massive 55mm diagonal sensor, a properly matched imaging train is essential. The available combo kit provides a seamless, robust solution by pairing the camera with the QHYCFW3XL 9-position filter wheel and the QHYOAG-L Pro off-axis guider. The QHYOAG-L Pro and the QHYCFW3XL mate directly, without an extra adapter.

The QHYOAG-L Pro is specifically designed for large-format sensors like the IMX461, with a 14 x 10mm prism that feeds large-sensor guide cameras. The QHYCFW3XL holds nine 2-inch mounted or 50mm round unmounted filters, or seven 50mm square filters, and QHYCCD lists it for the QHY461PH.

QHY461PH vs. KAF-16803 CCD Cameras

For years, the KAF-16803 CCD was the benchmark for amateur medium-format imaging. The Sony IMX461 sensor in the QHY461PH represents a fundamental technological advancement, outperforming its predecessor in nearly every critical metric.

• Resolution and Pixel Size: The QHY461PH offers 102 megapixels with 3.76µm pixels, compared to the KAF-16803's 16 megapixels and 9µm pixels. This is over 6 times the resolution, ideal for modern, well-corrected optics.
• Read Noise: At just 1e- to 3.7e-, the QHY461PH's read noise is dramatically lower than the ~13e- typical of KAF-16803 cameras. Such low read noise makes it practical to stack many shorter exposures instead of a few very long ones.
• Dark Current: The QHY461PH's dark current is approximately 16 times lower (0.003e- vs. ~0.05e- at -20°C), resulting in significantly cleaner long exposures.
• Quantum Efficiency: As a BSI sensor, the IMX461 achieves a peak QE of around 90%, far surpassing the ~60% peak of the front-illuminated KAF-16803. It is more sensitive across the entire visible spectrum.
• Download Speed: A full 16-bit frame from the QHY461PH downloads in under a second (1.3 FPS), while a typical KAF-16803 camera takes about 9 seconds. This dramatically improves workflow during focusing and acquisition.