[Renato1 (Renato)]

I bought a 6" Saxon Mak second hand nearly three years ago, but only got around to mounting and using it four weeks ago. The images on stars was great, but it was extremely disappointing on planets.

The out of focus bullseye pattern on a star looked concentric to me, but a small part of the outer ring wasn't as defined as the rest of the ring. Also, when very close to focus, the outer ring went triangular, indicating pinched optics.

Anyhow, it took me six hours over two cold nights of moving that bullseye pattern around to finally get it concentric, and get rid of that tiny smudge in the outer ring. The main problem was that every time I touched the screws, it would then take me 5 to 15 minutes to reacquire the star I'd been using, since the finder was then out of line with the telescope. In the end, I started using the moon to readjust the finder with, and then I would go back to the star.

Thus something that would have taken 3 minutes on a Newtonian, took me around 6 hours.

Anyhow, the pattern also shows less pinching than at the beginning of the exercise, probably because I didn't do the screws up as tightly. And the images of Mars and Saturn were significantly improved.

The exercise of collimating seemed considerably harder with this 1900mm focal length telescope, than with the 1356mm focal length 4" Mak I did a week and a half ago to psych me up for attempting the 6" one. I came to the conclusion that the Moon was pretty much essential for doing the 6" or I'd still be there trying to find the star to check the pattern on.

Has anybody else done this touchy exercise, or does it get easier with practice?
Regards,
Renato