ZWO ASI294MM Pro

The IMX492 sensor's dual-gain readout means you can run at very low read noise (~1.2 e-) in HCG mode, which is what makes the 294MM Pro a strong narrowband performer - short subs through 3 nm filters become tractable even at f/6 and slower. Bin 1x1 mode unlocks the full 11.7 MP at 2.315 μm, but the camera is most often run at bin 2 (the sensor's native 4.63 μm pixels) for a better match to typical seeing and easier file handling.

Pixel scale lands in a useful range for focal lengths between roughly 400 mm and 1000 mm. Below ~400 mm you'll undersample; above ~1000 mm you'll oversample unless seeing is exceptional.

Calibration discipline is non-negotiable. The 294 family has well-known quirks - amp glow, walking noise if guiding is loose, and bin-mode sensitivity to flats taken at the wrong gain. Buyers who skip darks and flats will be unhappy; buyers who build a clean library will be rewarded.

As a mono camera, budget for a filter wheel, an LRGB set, and at least one or two narrowband filters before this becomes a working rig. That's typically another $700-$1,500 on top of the camera itself.