I always wondered if the collimation would be maintained when the scope changes position. Tonight I tried it and found that this is not the case. With the 12" GSO Newt in the home position I rotated +-90 degrees around RA. The laser spot that was right in the center of the donut moved slightly above the donut.
Looking at my secondary it is clearly offset towards the side away from the focuser, byt about 1/4" or so. This offset is apparently enough for the spider vanes to flex a bit - though they look quite sturdy and tight. Maybe the effect is not as bad when the OTA is pointing up instead of pointing at the NCP.
Not sure what to do about this. Of course I casn recollimate each time I change the target but then I have to take the optical train out, refocus, etcetera. For now I'll ignore it and see what I get. Any suggestions are welcome.
... Henk.
Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80,
Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall,
Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS,
DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles,
Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50,
Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK,
Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17",
Website:Henk's astro images