I recently upgraded my ZWO camera from a ASI1600MM Pro to a ASI294MM Pro.  Some of you have asked for a comparison between the results of these cameras so I am posting these single calibrated Green subs which have been stretched to the same 0.25 background value and cropped.  The seeing was similar on both nights.  I used unity gain and default offset for each camera.  The width of each cropped image is about 40% of the full sensor width.

Here are the key parameters of each camera:

Camera:  ASI294MM Pro / ASI1600MM Pro

Binning: 2x2 / 1x1

Resolution:  4144x2822 / 4656x3520

Pixel Size:  4.6um / 3.8 um

Sensor Size:  19x13mm / 18x13mm

ADC: 14bit / 12bit

Full Well Capacity:  66,000 / 20,000

QE Peak: 90% / 60%

Sensor Illumination:  Back Lit / Front Lit

Cooling: -35C / -45C

FITS file size:  23MB / 32MB

Cost:  $1480 / $1280

Same camera housing and backfocus

With my C11EdgeHD scope:

Pixel Scale:  0.34 / 0.28

FOV:  24’x16’ / 22’ x 16’

Note that the ASI294MM Pro is capable of unbinned imaging, but that pixel size (2.3um) is smaller than I need, plus it reduces the effective ADC bit depth (14 to 12) and well size (66k to 20k) , while increasing the file size by a factor of 4.

I almost didn’t post these results, and I wouldn’t have had I not promised some of you that I would.  They are too dependent on seeing and guiding performance. I did numerous comparisons – this is a representative image of the same object on subsequent nights with similar seeing.  But for the other comparisons I did, seeing and guiding made a big difference in the comparative image quality.  You really have to do this comparison on the same night with the same object, and even then seeing could change.  So this is just a single rough data point for you.

I see the following:

-  The 294 captures more object signal as expected, but it is not a dramatic difference

-  The 294 is a bit “blotchier”, perhaps due to the binning but also because I don’t think the amp glow calibrates out as well as the 1600.  This "blotchiness" does not show up in the less stretched final image.

-  The biggest difference, not shown here, is that the 294 bright stars don’t have the microlens diffraction artifacts of the 1600.

For most people, it is probably not worth upgrading to the 294 from the 1600.  But if buying new, I think it is worth the extra money for the 294, especially because of the option to use the small pixel mode (1x1 binning) for smaller scopes.