[JA]

Originally Posted by CalvinKlein

Has anybody here tried using an ASI071 MC-Pro with wide angle lenses - example 35mm F1.4 ? I'm considering buying one and would like to be able to use it for DSO and nightscape imaging.

Whilst I haven't tried with the ASI071, I have used various wide lenses with various DSLR fullframe bodies for astro. In this use coma and astigmatism are often obvious abberations that you will have to contend with particularly at wider apertures. Certainly you will get the wider view that you want with the larger sensored ASI071, but you will also expose limitations in the optics as you start to use more of the image circle of the lens compared with using that same lens on the smaller sensors you mentioned: i.e: The likely abberations you were concerned with (probably coma and astigmatism) will get worse.

Originally Posted by CalvinKlein

I've tried my 14-24mm and 35mm EOS lenses with my ASI1600 and ASI183's with rather awful results (like stars in the middle being in focus but out of focus or severe aberations towards the outer edges).

I tried stopping down and adjusting the flange-to-sensor distance.

Correcting any error (if there is one) in the flange-to-sensor distance may improve the situation, but that's unlikely to be in error if you are using a one piece camera adapter. Maybe there is some load induced tilt, depending on lens support/play.

Stopping down will certainly improve the situation as the sensor sees less of the lens and its potential edge abberations, but the real improvement will probably unfortunately only be with a different lens, unless of course the Canon 35mm f/1.4 you have is the Canon EF 35mm f/1.4 USM LII which is EXCELLENT. The previous version, the Canon EF 35mm f/1.4 USM L suffers from very significant coma and astigmatism. See excerpt below prepared from lenstip.com comparing it with the new version II. The new version is quite expensive, but if you want to get most/all of the way there you could consider a significantly less expensive Sigma 35mm f/1.4 Art lens or Sigma 40mm f/1.4, also excellent.

Edit added:

You could also try a Samyang 14mm f/2.8 UMC for your 180 degree vista and you would only need 2 panels. It is very sharp edge to edge with very low coma. I haven't experienced it, but some complain of QC issues and sample variation with this lens. Another possibility if you are adventurous is the Nikon 14-24 f/2.8 which is also very well regarded and I've heard of Canon Astro shooters adapting it for their use on Canon bodies due to its sharpness and low coma.

Best
JA