Quote:
Originally Posted by Elio
Wonderful sujects that you have there...well done! 
A question: you say "200mm clear aperture", what does it mean?
Since obstruction is 55% what is actual diameter of the tube?
Many thanks 
EDIT: sorry but I heared that in astronomy it's more important the T-stop instead the f-stop, what do you think about it?
Thanks again... |
You are quite correct! What is the T-stop of an FSQ 106 with/without focal reducer? With more than twelve glass to air interfaces light flux losses will add up.
I can only go on the results I am getting with the RH200.
The central obstruction of the RH200 coincidentally is the size of the objective aperture of an FSQ106! The annulus is about three times this area.
Bert