GSO 6inch F4 collimation

[astrosathya]

Hi everyone,

I recently got myself a GSO 6" f/4 astrograph, but seems like the secondary mirror was quite off. I then tried collimation using Astro Baby's tutorials, and others around the net. I've had a few Nets during the past 20 years, but this one seems to be a bit of a pain to get right. The secondary holder is a bit stiff. Anyone here done any mods for the scope and have reasonably good performance? I'be attached an image with Mire De Collimation circles. Image shows the reflection of primary, followed by the edge of secondary and followed by the grey card placed behind the secondary, which ends with the focuser tube. Any help will be appreciated.

Edit: If I were to move the secondary towards 2'o'clock position, could it solve the problem?

[alacant]

55 minutes ago, astrosathya said:

secondary towards 2'o'clock position

Hi. Yep, down toward the primary -maybe half a turn anticlockwise of the centre bolt- and then upwards should do it. It maybe OK as it is; do a star test in and out of focus. The tube should be short enough to adjust the primary and view at the same time.

HTH and clear skies

[astrosathya]

24 minutes ago, alacant said:

Hi. Yep, down toward the primary -maybe half a turn anticlockwise of the centre bolt- and then upwards should do it. It maybe OK as it is; do a star test in and out of focus. The tube should be short enough to adjust the primary and view at the same time.

HTH and clear skies

Thank You.  With a secondary mirror this large, its quite difficult to really say. I'll try it out tonight.