For galaxy imaging, I really like the Sony 694 chip in my Starlight Xpress H694 camera. But the problem is that I always need to change my complete imaging train to use it (different filter wheel, different adapter...) So, I decided to get a FLI MLx694 camera. Plus the FLI can be cooled 40 degrees below ambient (vs. 20 below ambient of the SX camera).
The MLx694 does not have the same backfocus as the ML 16070. But the chip is so small, that it's unlikely that the chip stretches into curved areas. So, that shouldn't be a problem.
After a few weeks, the FLI package came - camera looks exactly the same as my ML 16070. Installation was of course straight forward.
First I wanted to figure out if the wrong backfocus is a problem. Took a few images and analyzed them with CCDInspector:
A little bit of curvature, but except in the corners not too bad. Considering that I want to use the camera mostly for galaxies, it's probably good enough.
Next, I took bias and dark frames. For my first imaging target, I wanted to image M101 again and compare it to my image from last year that I took with the SX H694 camera.
First I took some flats - and was surprised. This is one Ha subframe:
And here is a master flat (20 subs):
I checked everything. Took flats in all kinds of ways (daylight, dawn, flat panel...) always with the same result. At some point I opened a flat in Pixinsight which DOES NOT stretch images right away, and this is what I saw:
It turned out that the small 694 chips gets a perfect image with no vignetting (the TOA super reducer creates a huge image circle and the 50mm filters are much larger then the censor). Plus I (apparently) did a really good job of cleaning the chip from dust! Impressive!