The CMOS Revolution
At the time I acquired my new StarlightExpress SXVR H-694C CCD camera in 2010, it was considered to be at the forefront of CCD cameras for astrophotography. Its SONY HAD694 ExView CCD detector was
state of the art at that time. CCD technology was fully mature in 2010, but by the end of that decade this technology was starting to be superceded by newer, more sensitive detectors called complementary metal oxide semiconductors (CMOS), which are less expensive to manufacture.
I started seeing advertisements in the astronomy magazines about new cameras using these chips. The first thing that caught my eye was the fact that these new CMOS cameras had much larger sized chips than the 16mm diagonal size and 6 megapixels of my StarlightExpress 694, and they were much less expensive.
However, when first used for astrophotography, they had some disadvantages such as electronic noise caused by "amp glow" as well as lower Analog to Digital (AD) conversion ratios. This caused me to take a "wait and see" attitude about these new cameras.
Then, in 2021, I saw an ad for a new CMOS camera that had features that were previously not available:
Greater sensitivity due to their back illuminated design (all of the amplification and transmission circuitry had been moved BEHIND the pixels, for unobstructed light gathering) and new circuitry that eliminated the amp glow problem. In addition, this circuitry increased the Analog to Digital conversion ratio to 16 bit, the same as my SX CCD camera. And, lastly, a 256 Mb buffer chip to decrease the image download time.
And best of all, this new SONY IMX 571 chip had a 26 megapixel array that was 23.5 mm in diagonal size with smaller 3.76 micron pixels for finer resolution.
After seeing numerous spectacular images taken with thi new camera, I finally "took the plunge" and purchased one in late summer of 2021. It was the ZWO ASI 2600MC Pro, with the super sensitive SONY IMX 571 back-illuminated chip, with 16 bit ADC and the other features I had desired. At the same time, I also purchased STARIZONA's Reducer/Corrector III, so that I could image at a Cassegrain focus of f/6.3.
Below is a photo of my new camera and focal reducer mounted on the C-11, as well as one of the first images taken with the camera, a 1 hour 24 minute integration of galaxy NGC-891. As can be seen, this new camera is really going to be a performer!