That's neat Mike. Thanks. Cheaper glasses too.
To me using a coma corrector and taking out the sa with a schmidt type corrector makes a lot of sense. You might say it saves making a spider but wont arf attract the dew. Baker sort of gets round the camera blocking the light, mine is a MK1 5D, they are cheap now. His corrector is a cemented doublet which takes out 2 glass surfaces making 4 in total. That may well make coating less important especially on the doublet. His lens projects the image well away from it. The F5 main mirror finishes up at F4.5 along with a reduction in aperture to 17in so it seems that the extra power has to come from the lens. It's an absolute ##!!### to do anything with the lens as it has to be just optimised for coma only. Olso's optimisation isn't too good at just doing that and in my case it has to be reasonable with colour too. I use the wavefront analysis for that. Best so far is 0.4 p/v at 3 degrees and perfection in the centre or 0.4 p/v at 3 degrees and 0.25 p/v at the centre. LOL the 0.4 just wont go away. I don't want a semi of 3 degrees but that seems to help the ray error functions work more effectively.
It seems Baker went a bit further than Ross who compromised his design for sa and coma leaving a blurred circle of confusion that is still suitable for some uses. Baker pointed out that many optical systems have large amounts of coma some where in them so why not take it all out and fix SA another way.
I'm not much interest in anything other than the visible light range. IR in particular is more likely to be pollution where I live and UV doesn't figure highly either.
Off topic buy one source of confusion is glasses. Should the N types be used now? eg N-B7 rather than BK7 for instance.
I'm not giving up on Baker yet but that one is the 1st alternative of any interest. Both sound cheaper and much easier to make than a 6in apo. Not so good but cost more than makes up for that.