To cope for possible mirror flips and tube flexures on my cheap GSO Newton 10" I've recently bought an OAG.
Having little backfocus (my corrector is 55 mm) to put my AP setup (wheel + camera) I opted for a TSOAG which adds a mere 9.5 mm to the whole.
I need to point out following issues:
1) First of all the star pattern is very very far from the Gaussian profile I would expect. This is true in particular for brightest stars. I haven't figured it out yet how can a prism deform the pattern of a star in this way.
2) It is very difficult to me to find the optimal distance of guide camera sensor plane to reach a proper focus. Given the unusual star pattern generated by the prism indeed it is even impossible to use a Bathinov mask. I calculated that I'm approximately 0.15 mm off proper focus.
3) I noticed that the intensity of the star image on the sensor changes as I move the scope. Some stars even disappear. Moreover this generates "star lost" problems during calibration in PHD2.
4) I make use of both NB and BB filters that are not parfocal each other. This means that if I get a proper focus with NB filters I'm off for BB filters and viceversa. How can I cope with this given that the difference can be so tiny that I cannot use even 0.5 mm extenders?
I rely on your experience to find solutions to my problems...
Thank you in advance!
Edited by Fukinagashi, 21 May 2019 - 04:16 AM.