In anticipation of the arrival of my TEC 160.. I seek wisdom.
My set-up will have the 160 (f.l. 1120mm) topped by an AstroTech 65mmQuad APO (f.l. 400mm) and an Orion Starshoot Autoguider in a wee little finder scope of about 120mm focal length.... Using PHD guide 2.....AP Mach 1 mount.
Is 120mm enough f.l. to guide 1120mm?
What about using the 400mm f.l. to guide the 1120mm? better?
Would it be overkill to guide the 400mm scope with the 1120mm scope?
Is there a rule of thumb for this sort of thing?