I just received my new fast wide-field astrograph, a Guan Sheng GS-550 (aperture 153 mm, focal length 612 mm, f/4). It's a fantastically 'maneuverable' OTA (so light, even for a steel tube), and looks well constructed. The monorail focuser also looks well constructed, and should easily handle my light imaging train (1 kg). It's basically this model, except I got it from Andrews Comm.
http://www.teleskop-express.de/shop/...-MONORAIL.html
BUT... this is the first ultra-fast newt I've owned (my previous 8" newt [back in the day] was an f/7.5), and I'm just re-learning collimation on these babies. With f/4, it seems it's a whole new ball game. I currently have a Cheshire eyepiece, a collimation cap, and a Laser collimator, but I might need to invest in a Catseye kit?
Anyway, to my first question on this new adventure. I see six primary mirror collimation knobs on the GSO newt - three are relatively large, and 3 are smaller and have a flat-screwdriver-head (you can see them on one of the photos here:
http://stargazerslounge.com/topic/19...ing-newtonian/). I presume the larger knobs are for collimation of the primary, and the smaller ones are the locking screws, but, when I tighten the locking screws up, I also get mirror movement.
Also, in these fast newts, should I expect the secondary to be offset?