|
I have a similar Telescope design called a Catadioptric Newtonian, Diameter = 130mm, OTA length 500mm, FL=1000mm due to the 2x lens built in between the Primary and the secondary which focuses the primary's parabolic light onto the secondary and is supposed to remove or minimise coma and other false colour issues.
I had no end of dramas with collimation and ultimately had to get the OTA replaced as it couldnt be collimated to a point that allowed proper focus.
Now that I have a new OTA, the problem has been resolved but for a small newtonian (or any for that matter) I would steer clear of these as a beginner as it just creates too many headaches and introduces another point of failure and complication you just dont need.
Buy a normal length simple Newtonian Dobsonian or GEM mounted tube and enjoy the simplicity instead.
Seriously.
Chris
|