The 071 sensor is not back illuminated. A back illuminated sensor has higher Q.E. and reduces noise. From the ZWO site...
"Sony’s back-illuminated CMOS image 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.
Sony has newly developed a unique photo-diode structure and on-chip lens optimized for back-illuminated structures, that achieves a higher sensitivity and a lower random noise without light by reducing noise, dark current and defect pixels compared to the conventional front-illuminated structure."
The 071 has a 14 bit ADC (2^14 or 16,384 bits) vs. the 2600 16 bit ADC (2^16 or 65,536 bits) and therefore has a deeper well depth and much higher dynamic range. The 2600 also has a better dew heater. The 2600 has zero or almost zero amp glow. As to sub time difference between the two the 2600 should be quicker. As to how much I can't say. I don't have the 071.
Simple GET the ASI2600MC Pro...
Edited by Jim Waters, 26 March 2020 - 01:07 PM.