Ran it a hundred times now - it's the second set of data with the new Baader UV/IR filter causing the issue - seems ONE of the 2 filters is NOT optically flat, and as such, despite even using FFT routines, the 2 will NOT register properly. I redid the first set of data with some new processing techniques I relearned (thanks Louie!), and I believe those to be superior to the Baader UV/IR set (sharper stars and less halation/bloat with the Optolong!). So, as I mentioned, the Baader is now relegated to the visual role in the front of my Baader Maxbright.
Looking at the 2 sets layered directly on top of each other, the scale is SLIGHTLY different. It would appear that the Baader is disturbing the flattener, altering the optimal spacing, whereas the Optolong did NOT. In my original calculations when having the adapter made, I DID shorten the length by 1.4mm to account for the approx. 0.7mm of each glass substrate, and that worked precisely with the Baader LP/Opto UV mix, but NOT the Baader/Baader.
Here is a reprocessed stack from the first run. The now missing 1 hr 20 mins from last night has seen a significnt decrease in dynamic range (red cannot be pushed as smoothly) and increase in noise (it was nicely smoothed out with the entire set).
Now to grab them photons all over again and re-wrangle them.
Tilt maybe but don't think so. Not spacing. Examining individual subs shows a flat field.
I also changed uv/IR filters since the prior run so that threw off my standard focus position and other issues.Oddly the Baader uv/IR gave worse results than the $100 cheaper Optolong! Swapping back and will use the Baader for visual
Lewis, you certainly have a tilt. Bottom left has the tightest stars (at a correct spacing), while top right, bottom right and top left have soft stars (incorrect spacing from the corrector due to tilt), and those three corners have elongated stars.
The latest version seems to have nice stars though, but can be due to low res image at IIS.
Pretty decent Lewis Credit due where credit is due
And having put your sense of humour through the initial post , ,
I know what your sayin', ,
Good stuff, as they say : when the going get tough, the tough get going ??
Doing betterra than this duck I'm a 'bout as tough as wet toilet wipe,
Look forward to more ...
Credit due where credit is due 
