ASI294MM Pro is a back-illuminated, 4/3” format, 14-bit ADC camera with 4.63um pixels. It is the mono version of ASI294MC Pro, one of the top selling cameras from ZWO. It has an impressive 66ke- full well capacity and 4144*2822 big resolution.
Not only does it have a very high QE value with a peak at about 90%, but feature an ultra-low readout noise of 1.2e. If you are seeking for a small-format mono camera for astrophotography, then ASI294MM Pro gonna be your ideal choice.
14-bit ADC and 13stops dynamic range
ASI294MM Pro has very similar parameters as its color version. Both have the 14bit ADC and a high dynamic range of 13 stops, which is even higher than that of ASI1600MM Pro camera.
The back-illuminated CMOS sensor improves sensitivity and noise reduction – the key factors to enhancing image quality, while radically realigning their fundamental pixel structure from front-illumination to back-illumination. It has retained the advantages of CMOS image sensors such as low power consumption and high-speed operation.
With a conventional front-illumination structure, the metal wiring and transistors on the surface of the silicon substrate that form the sensor’s light-sensitive area (photo-diode) impede photon gathering carried out by the on-chip lens. A back-illuminated structure minimizes the degradation of sensitivity to optical angle response, while also increasing the amount of light that enters each pixel due to the lack of obstacles such as metal wiring and transistors that have been moved to the reverse of the silicon substrate.
Large well depth capacity, low read-out noise and high dynamic range.
The full well capacity of 66387e of ASI294MM Pro is near the top of all ASI DSO cameras. It ensures a very high dynamic range up to 13stops that will greatly reduce overexposure probability and help gain richer color gradation.
When the gain value is 120, the magical HCG high gain mode is turned on, the readout noise will be largely decreased (as low as 1.2e), and the dynamic range is basically unchanged.
Unlocked Bin1 Mode
One thing about ASI294MM Pro which can be very special is that the pixel size is switchable – the default setting is Bin2, but you can switch to Bin1 anytime in your astrophotography software to change the pixel size into 2.3um. This is what we called “Unlocked Bin1 Mode”.
Unlocked Bin1: 12bit ADC, 2.3um pixel size, 47 megapixels, 8288*5644 resolution, 14k full well capacity.
Bin2 (The default mode): 14bit ADC, 4.6um pixel size, 11.7 megapixels, 4144*2822 resolution, 66k full well capacity.
You can learn the more differences between unlocked Bin1 and Bin2 modes by comparing the performance charts.
If the sampling accuracy you get with the 2.3um pixel size falls into a reasonable range, then the unlocked Bin1 mode will help you get more object details. However, you will lose dynamic range and the bit depth of ADC. Also the image files you get at Bin1 will probably be 4 times bigger than Bin2.
So in the end the unlocked Bin1 mode is double-edged, you may choose to use it or not on your own.
There are four screws on the camera that seal the sensor chamber. This kind of design has been extensively tested and is very stable. Even when used in higher humidity environments, ASI294MM Pro will still work fine without dew problems.
As ZWO’s latest BSI (backside illuminated type) mono camera, ASI294MM Pro has very high QE performance, not only higher than its color version, but even ASI1600MM Pro. It is estimated that the QE peak value is about 90%.
ASI294MM Pro vs ASI1600MM Pro
Two-Stage TEC Cooling: Ultra-Low Dark Current
ASI294MM Pro uses two stage TEC cooling that can lower the CMOS sensor temperature to 35c~40c below ambient, which can greatly reduce dark current generation and sensor noise even with extended exposure times.
The unique dark current suppression technology can even further reduce dark current noise. When it’s cooled to -20℃, the current noise can be as low as 0.0022e/s/pix, which is completely negligible!
Please notice that the camera needs to be connected to an external 11-15v power supply to implement the cooling function. We recommend you use 12V@3A DC adapter (5.5*2.1mm, center pole positive) or lithium battery with 11-15V to power the camera.
USB3.0 & 256M DDR3 Memory
The ASI294MM Pro is equipped with a USB 3.0 transmission interface and a built-in 256MB(2Gb) DDR3 cache to ensure stable and secure data transmission. Under long exposure, it effectively avoids frame dropping and greatly reduces the glow effect caused by slow reading speed.
Notice: For the possible amp glow that shows on your images, please refer to this tutorial: “What is Amp-glow and how do I manage it? “