I'm trying to make the PST mod on my C14 with an off-axis 160 ERF-D filter and a BF1800 Lunt. I have already made this modification on a tecnosky telescope of 152.
During my first attempt I did not succes to do the focus. I did several tests with long rings.
Valery in this old post :
You wrote :
Do you think this setup can work ?Large ERF (say, for a C14) has another option. If the seeing does not cooperate, one can just stop the aperture with 6" off axis mask.
The initial F/D goes from 3910/355 = 11 to about 3910/140 = 27.9.The diameter is reduced with the ERF filter. I take as 140 diameter because the erf 160 is a little eclipsed by the support of the secondary mirror.
PST Fabry-Perrot is optimal at F/D = 10. Maybe it's the problem if my F/D is at about 28 in this configuration ?