I have completed initial imaging setup for the Skywatcher MN190, and wanted to demonstrate my last comments on Contrast Factor numbers.
Here are two images of the same object: Eta Carinea.
http://www.astrobin.com/full/180326/0/
http://www.astrobin.com/full/185615/0/
The first is taken with my 10" imaging newt with a Baader Coma Corrector on the camera (this is my lightweight f5 newt).
The second is taken with the new Skywatcher MN190 f5.3, which of course has no coma corrector on the camera. Both sub taken at 209" with the same Canon 450D Full Spectrum camera with minimal processing ( i think I did more processing with the first one, the second only has auto levels done). The first was taken at Bretti the second taken in my backyard observatory. The first was the NEQ6 on its tripod, the second the mount head was on my pier.
Love the edge to edge coma free field of the MN190. Sure it is wider field of view to the 10", and the 10" gets in a bit closer; however, I much prefer the contrast and stars in the MN190. Of course the 10" has a higher Contrast Factor - which is my point - that number doesn't tell you much at all.
Note: Submissions to Astrobin are jpegs for the public gallery.