Hi Chris,
http://www.hobbex.se/internt/artikla...p_Saturnus.PDF
Try the manual here, it is also a short tube Catadioptric Newtonian reflector telescope, it is 114mm instead of 150mm, but the same type of telescope.
Short tube models v long tube models
114mm - f500mm v 114mm - f900mm
150mm - f1400mm v 150mm - f750mm, 1000mm or 1200mm
or you can type in google "Short tube telescope manual" and you will find a few of these type of manual, including the Celestron short tubes 114mm and 130mm Powerseeker models.
They have a negative lens (focal corrector lens, not barlow lens as many incorrectly coined, as barlow does not correct spherical aberration) in the bottom of the focusing drawtube to correct the spherical aberrations introduced by the very fast spherical mirror, but the result is not too good with image clarity, especially away from the centre field of view.
It is also not strictly a Jones Bird telescope design, as the focal corrector of Jones Bird design is in the main telescope tube, not at the bottom of the focuser drawtube. At best, these focal corrector scopes are fuzz scopes on high magnifications even when collimated (harder to collimate with the corrector lens present).
See comparisons of short-tube spherical versus parabolic mirror telescope of the same 150 mm size:
http://www.astronomyforum.net/archiv...hp/t-6153.html
Hope that helps.
Kind regards,
Bill
