Hello folks,
I have a Denk Binotron 27 system with power switch and OCS. It works very well in refractors, but not so hot in a Newtonian. The stars are larger than when using a regular eyepiece + coma corrector, and of course stars near the edge are even worse. I mainly use it in low power mode for viewing clusters, but sometimes switch to medium power, or high power for planets and doubles.
I see there's an APM coma-correcting telecentric 1.5x barlow, and also a 1.7x Baader version. However, I'm not sure how well they'll work with the power switch, which is effectively changing the back-focus a lot from the more standard 100-and-something path length of typical binoviewers.
I've also read comments that for low power, you'd be better off using a linear binoviewer + standard coma corrector.
My newtonians are F/4 and F/5. At some point, there may even be an F/3.5.
