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[stargeeser]

Not sure where to post this, but since I have an sct I'll try it here. 

Could a dioptryx correct a scopes astigmatism or it it strictly for eye astigmatism?

[ButterFly]

Any.  One corrects astigmatism by introducing astigmatism of opposite polarity along the same axis.  To check what is causing the astigmatism, defocus so you see the ellipse, then rotate each element, such as the eyepiece or your head (with your eyes still attached to them).  Astigmatism rotates along with its source.  With an SCT, it's impossible to separately rotate the primary, the secondary, and the corrector, so treat them as one unit.  Process of elimination will get you to the combination of all three - head, eyepiece, diagonal separately rotated.