ZWO ASI2600mm Pro Camera - Initial Tests

After waiting for almost 2 years the new ZWO ASI2600mm Pro camera was finally announced back in early January. The baby brother to the ASI6200 (which has a full frame sensor) the 2600 is the APS-C version, with a Sony IMX 571 sensor. I pre-ordered mine in mid-January, and received one this past Tuesday. 

ZWO ASI2600mm Pro

First step was to power up the camera and get the settings dialed in with SGP. Once I was confident that SGP was controlling the camera I ran the camera for 16 hours taking the all important dark frames, 40 in each set of 30s, 60s, 120s, 180s and 300s duration at -10 degrees Celsius. Since I was interested in the two key gain settings (0 and 100) I took two complete sets of darks. As promised by ZWO, the dark frames showed no amp glow at all! My ASI1600 was able to reach 40-45 degrees below ambient; the 2600 can only muster 35 so I settled on -10 as a good operating temperature. This gets me to 0.00075e/s/pix, which in other words means that a 300 sec exposure will only produce about 0.225 e of dark current noise, well below the 1.0-3.3e of readout noise. Hot summer nights might be a bit of a problem as the limit to run the camera at -10 degrees C is about 77 degrees F. 

On Thursday night I loaded the camera up on the GT102 to get some initial images while I had some clear skies. The moon was out, more than 3/4 full and there were still some high level thin clouds, so results weren't great, and I really couldn't take any broadband images. So I decided to just take a few 300 sec and 600 sec Ha subs on the California nebula.

My biggest concern prior to setting up the camera was that my existing set of filters were only 31mm in size. Calculations indicated that 30-32 mm was the minimum for the GT102 optical configuration so I was really expecting some serious vignetting of the images. I'm not sure yet if the EdgeHD11 (my larger telescope) would fair even worse (will test that scope later), but replacing the filter wheel and filters with all new 36 mm ones is not an option at this time as the cost is prohibitive (well in excess of $4500).  

The initial test images did show the vignetting, as can be seen in the picture below.

Since the aspect ratio of this sensor is much greater than the 1600mm, I could easily accept a 15% crop of the image in the longer dimension and still end up with an image size a bit larger than the 1600mm was able to produce. Cropping the image to 5200x4176 from the original 6248x4176 gives a pleasing, more 'square-ish' result that eliminates the vignetting. 

So far the results look very good. The images hold up to some aggressive stretching in the post processing since the 2600 has a 16 bit ADC, whereas my 1600 had only 12 bits. This is a huge improvement in dynamic range output of 14 stops, which will significantly improve the image sharpness and contrast, and also create smoother and more natural color transitions.

Download times are on par with the 1600, about 6 seconds per image. File size is much larger of course, coming in at 51 Meg per sub.

Once the skies clear up and the moon is out of the way I'll take a complete run of Ha subs on this object so that I can fully calibrate the images with darks and flats. I'll report on that in a future post.