Riccardi reducer for APS-C

[billhinge]

Sorry, wasn't sure where to post this but it is related to cameras

I have an Altair 80mm f6 Apo, currently with the native Atair x1 dedicated flattener. I'm looking to buy a new camera later this year but am worried about coma in the corner of the image

I was thinking of buying a KAF8300 ccd but read about end of life status, argon leakage, microprism effects so its put me off slightly. So I was thinking I may wait for something more modern like the QHY268C.

So for an APS-C (IMX571) would you stick with the dedicated Altair flattener or go with the APM Riccardi x1 or 0.75. My thinking being while the Altair flattener may be dedicated its built to a price point

The thing I'm confused about is backfocus, currently the Altair 80mm is supposedly 55mm, blurb on x0.75 says

The illumination and correction is made for chips up to the APS-C format or the best known Kodak KAF 8300 chip - so far so good

Adaption towards the refractor - required backfocus

The corrector modifies the focussing point. It wanders towards intrafocal. Having screwed and not pluged in the corrector/reducer to the focuser You need to have a backfocus of at least 170mm. (Hmm?)

For focusers with a free aperture starting at 68mm we recommend to put the reducer inside the focuser. 

But it also says

Backfocus to CCD from the female M63 End to the CCD Chip:

TS Triplet APO 80/480mm / APM Apo 80/480mm / Lomo APO 80/480mm: 81mm - Looks good, why would the Altair be different
APM APO 80/500mm: 80.7mm

Given it works for the  TS and APM 80mm triplets is it safe to assume it will work for the Altair 80mm f6?

If so, does it mean backfocus will be 81mm rather than 55mm (where did the 170mm come from?)

 

Thanks

Steve

[billhinge]

I contacted Altair and got a quick response back,  apparently starlight may  have an  adapter so  emailed  them