How does tilt relate to eccentricity?

[Gernot Schreider]

If I have some tilt in my image train, e.g. 7%, how much eccentricity would that create assuming there are no other issues creating eccentricity, i.e. optimal optics and mechanics of the system ?

I would appreciate some explanation of the above relation.

Cheers
Gernot

[han.k]

Hello Gernot,

I assume the HFD will increase linear the eccentricity. But the tilt measurement compares different corners of the image. Normally stars get less round the further away from the optical center but the corners should be the same and do no result in a tilt. The principle behind tilt measurement are described here:

http://www.hnsky.org/astap.htm#inspector

Cheers,
Han