Early in the morning just past midnight for some reason I thought it a good idea to swap cameras on the RASA 11 in the middle of a nice dark sky night. Big mistake. I know better, really I do.

With the RASA's depth of focus equal to twice the diameter of a red blood cell it takes time and luck to reacquire proper sensor tilt and backfocus, in this case over two hours of screw turning and fiddling and cursing.

At the end of that I was pondering what to image as a test exposure, someplace with stars edge-to-edge. Something from my bucket list that's new to try. This time of year Barnard E is low in the eastern sky, at 28 deg at 3 AM, allowing a two hour window of opportunity.

Original upload:

Other than cropping about 1% for dither fade around the edges, this is the full frame 6k by 4k FOV. Very basic processing. No deconvolution or star reduction, just an EZ Suite soft stretch and then to Affinity Photo for denoise in the blacks and color balancing. While the stars are not perfect they are better than I've seen out of the RASA for some time, so I'm really pleased.

Present herein are Barnard E (B 142, B 143), LBN 126, LDN 695, LDN 689, LDN 690, LDN 707, LDN 703, LDN 687and LDN 700.

With such a dense rich starfield one is reminded of Olber's Paradox.

B revision is cropped and framed to highlight the key objects, without additional processing.

---Updated info for RASA 11 users:

Okay, after getting some sleep I decided to dig into this matter and solve it. There is a happy ending to this saga. I found that there is enough backfocus distance to couple the 68mm Camera Tilt Unit from Gerd Neumann Jr. (needed for f/2.2) to the Baader UFC filter drawer assembly.  The rig includes Baader's 15-20mm adjustable spacer, to set precisely the backfocus, an adjustment also needed when changing between filters of differing glass thickness. On the RASA, failing to account for filter thickness shifts to backfocus will distort stars in the corners of a full frame or larger sensor.

Some tests showed this rig to be an effective solution to all the troubles of the first night.  Everything is now easy to adjust. For those interested, I've posted a photo.

I rigged this in the following order to allow the f/2.2 light cone to have minimal vignetting: 

The camera screws into UFC filter drawer with a UFC 54mm plate, keeping the filter drawer as close as possible to the camera sensor.  To align the rectangular sensor in parallel to the edges of the 2x2 square filters, it was necessary to use thin brass shim stock between the M54 UFC plate and camera, such that upon final screw thread tightening, the edges of the filters and the sensor are made parallel. The filter drawer in turn mates to the 68mm CTU, which mates to the 15-20mm spacer, and finally to Baader's RASA adapter plate, so everything upstream of the CTU is 70mm clear aperture.