I was quite happy with my ZWO ASI178MC Cool camera, which was the first OSC camera I've ever got. Taking images with it was a lots of fun, and OSC really makes imaging and processing simpler. Unfortunately, for that simplicity you pay with somewhat diminished sensitivity and resolution. After couple of years I've decided that it is time to get a bit more versatile OSC camera.

My choice was Moravian Instruments C1+12000AC camera. The camera is based on the color version of Sony IMX304 CMOS sensor. The camera is very compact, weights 675 g and build quality is excellent. Its matte black finish gives the camera very professional look. Camera is delivered in a hard case, with all the necessary cables and power supply included. All the connections are situated on the back of the camera: external power, USB 3.0, guider port and filter wheel connection, as well as desiccant plug.

Regulated Peltier cooling can cool the sensor more than 40 C below ambient temperature. Imaging is possible using USB port only as power source, but for active cooling external power supply (included) is necessary.

 

Sony IMX304 CMOS sensor has 3.45 3.45 m pixels and resolution of 4112 3008 pixels. Image area is 14.19 10.38 mm. It is a front illuminated sensor with global shutter and 12 bit A/D converter. It provides nice image scale with moderate focal length telescopes. I've seen nicer dark frames than what I get with this sensor. But, amplifier glow and pixel imperfections calibrate quite well in real images, provided that you don't take too long subframes.

For DSO imaging I get the best results with camera gain set at 40, taking subframes up to 3 minutes long. Since read noise of the camera is low, hundred or more of subframes can be stacked to get images with good signal to noise ratio. With number of satellites growing every day, it gets increasingly difficult to take smaller number of longer subframes like you would do with a CCD camera. With CMOS cameras stacking a large number of shorter subframes enables us to get rid of annoying satellite trails also.

This camera is available with several different telescope or lens adapters. Mine is equipped with T2 adapter, which is tiltable to be able to get the sensor perfectly aligned with the optical plane. That is quite unusual for a sensor of this size, but it might be quite useful with fast focal length telescopes like RASA. For some reason backfocus with this adapter is 18.5 mm instead of more common 17.5 mm. It is not a problem, but one must be aware of that when precise positioning of the sensor is important.

This camera is also available with monochrome version of IMX304 sensor. The difference is that in color camera RG&B filters are integrated in the sensor in a pattern called "Bayer Matrix", while monochrome cameras need external filters to produce color images. After some experimentation I determined that the exact pattern of the filters on the color sensor is BGGR. That is important to know in order to produce color images from raw subframes using process called "Debayering". For monochrome cameras Moravian offers several variants of filter wheels.

Moravian has some other accessories for C1+ series of cameras like lens adapters or nicely integrated off-axis guider (OAG). But, I am using ZWO OAG and QSI Nikon lens adapter that I already have. With some T2 extenders and spacers they work perfectly well with this camera also. On the picture left you can see that the camera is used together with Astro-Tech 2" field flattener. That is mostly because of the guide camera connected to OAG that is situated far from the optical axis. Without the flattener stars on the guide camera would be distorted and that may affect guiding.