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Emuhead
26-08-2021, 06:25 PM
Hi all,

Was going after improving my collimation and so bought another collimation tool, a '2-inch TS Optics Concenter eyepiece' which makes secondary alignment under the focuser tube a breeze.. and its highlighted the issue nicely.

The secondary holder seems a little too long (or the spider placed a little too close to the focuser). I couldn't get the secondary to present as a circle whilst simultaneously falling nicely into the concentric rings of the eyepiece.

Removing the secondary spring completely brought the secondary holder closer to where it should be, but now that the secondary holder is touching the secondary mount hub. With only a minuscule length of the secondary collimation screws protruding holding the secondary in place, the only way i can see to perfectly center the secondary under the focuser is to shave off some of the holder length to create the space (or move the spider further away from the focuser/primary which isnt possible due to running out of tube).

Has anyone been there, done that?

The 3 images:
- My finishing position (much better but not perfect)
- A schematic, professionally drawn :), showing the red section of the secondary holder im intending to shave down.
- My starting position (bad)

Scope:
Skywatcher Quattro 8" (stock)

multiweb
26-08-2021, 06:45 PM
You could have achieved the same result by inverting the spider vanes.

Emuhead
26-08-2021, 06:52 PM
Oh i havent made the change as yet but inverting spider vanes looks like it could work.

Is this a common issue?

Will update shortly.

multiweb
26-08-2021, 06:54 PM
Is that a second hand scope? Maybe the owner put the vanes back the other way around when remounting the secondary. The collimation screws go through so doesn't matter which side you feed them through.

Emuhead
26-08-2021, 06:59 PM
I bought it new however have had the spider out once, and noticed that 2 of the vanes were around the wrong way, which I reverted.

multiweb
26-08-2021, 07:42 PM
ha ok then try to reverse the spider see if it makes up for the offset.

Emuhead
26-08-2021, 09:14 PM
Perfection achieved. :eyepop:

Thanks a million! :thumbsup::thumbsup::thumbsup: