Question...........

[FlashDrive]

My question is .... having a ' Crayford ' Focuser on the back of a SCT , does it do away with the use of the original focuser.

or ....does it ' supplement ' the original focuser to ' combat ' mirror shift.

I'm assuming you ' focus ' with the original focuser, and then re-focus gently with the Crayford to correct the mirror shift in the SCT ...!!

Would this be right !!

Col....

[Merlin66]

Hmmm, not really.
But the selling point is that when you’re close to focus, the external Crayford Reducers the mirror flop during final focus....
IMHO I’ve never found this a real problem.

[The_bluester]

Yep, coarse focus with the original and lock the mirror if you are lucky enough to have mirror locks then fine focus with the crayford or whatever else you have. I have a Meade zero image shift focuser here that I swapped (Plus a factory Celestron focus knob) for my feathertouch with another member on here. It has maybe 15mm of travel so you rough focus with the original then fine with the other.

[Ukastronomer]

supplements it