The Universe shows significant vignetting with my 8 inch f/4 newt; it is even more pronounced (as I expected) with the VRC 6 and .5x focal reducer (f/4.5 effective focal ratio). The sensitivity of the Universe with 3x3 binning is outstanding--although at the cost of reduced resolution, of course. And even with this binning, the FOV is still huge.
My targets for the night were the Needle Galaxy (NGC 4565), M81 and 82, and M3. I was only able to get 5 images of M3 as the clouds rolled in. I took no darks. I used max gain and no noise reduction. My goal was not to produce high quality, printable images, but to see just how well the Universe would work in a more "real time" mode with short exposures. I also wanted to get an idea of how well it would work in combo with the VRC 6.
My conclusions: the FOV is impressive, as always, but I think the Universe is really more suited to a larger aperture scope. I can't wait to try it with my 14 inch ACF. I still expect to get some vignetting with the MFR II focal reducer, but I suspect this combo will match much better with the outstanding capabilities of this imager.
|M81 and M82|
|Cropped image of Needle|