Hi everyone, with quite a delay I am eventually posting the result of a comparative test I run few months ago between two of the most popular cameras used in hi-res imaging. The ASI290MM is probably considered to be the best monochromatic camera for the planetary imaging in the market at current time, as well as the ASI224MC probably being the reference among color cameras.
Since generally monochromatic cameras are considered to be superior to color ones for hi-res work, I wanted to test both these two cameras in rapid sequence, imaging through the same telescope and working in condition as similar a as possible (seeing, sampling, etc.).
To test the cameras I used a TeleVue 2x barlow with a custom made adapter with variable length to adjust its power and compensate for the different pixel sizes between the 224MC and the 290MM. So the two cameras worked with a similar sampling.
During the test the seeing was pretty good and stable. I integrated the same amount of total light for both the ASI290MM and 224MC (5 minutes), in particular the image with the 290MM is the stack of the best (33%) frames from 4x30" (Red) and 3x30" (Green and Blue) videos sequences, while the image with the 224MC is the result of stacking the best (33%) frames of 5 videos of 60 ".
The panel showing the final comparative result is reduced to respect the forum rules, the full resolution panel is anyway visible on (and can be downloaded from) my website here: https://www.glitteri...tem/i-58XwmBj/O
I processed both images the best I could to bring out all the details available, so the final results are probably a little more contrasted than I normally do. I didn't apply any noise reduction to the final result to stay true to the cameras output.
1) The 290MM produced a slightly better Jupiter, with finer details, especially in the blue channel.
2) Colors with the 290MM were more evident, I had to push less on the saturation comparing the 224MC. This confirms that the RGB filters provide a better color separation than the Bayer matrix, as also quite easily noticeable looking at the 224 relative color curves where there is much more overlapping between the green and the other channels.
3) The processing time with the mono sensor was significantly higher (you have to do part of the processing on each channels separately instead that working on a already assembled RGB image).
4) Taking RGB sequences in variable weather conditions (as in my case, where most of the nights including the one of the test are affected by passing clouds with clear windows limited to 7/8 minutes) is a real challenge, I had to redo several times the RGB sequence due to passing clouds during the imaging of one of the channels.
Ultimately, is a monochrome sensor worth the extra complexity ?
I leave to each one drawing their own conclusions, in my opinion the answer is 'yes' if you want to push your own telescope to its limit (when the seeing allows it).
However for a "normal" use or for observing sites with poor or average seeing the 224MC confirms to be a great camera that delivers comparable results of a mono sensor, but with much less complexity in shooting and processing and overall lower cost, in particular when also the filters and filter wheel are added to the package.
Let me know what you think.
Edited by Marco Lorenzi, 19 September 2019 - 01:11 AM.