How do I adjust the spider vanes?

[Mr Flibble]

Hi all,

After following the tutorials on collimation by Astronomy Shed I've discovered my secondary holder is just slightly out. How do I adjust the spider vanes to centre the secondary holder? I've tried turning the chrome nobs on the outside of the OTA (not sure which way to turn them) but they are very tight and don't budge.

Thanks.

[Moonshane]

hi David

You are in the right place. They turn anti-clockwise to loosen and the opposite to tighten. to move the secondary towards you, both the one close to you you and the one furthest must be loosened but especially the one furthest . tighten the one nearest to you and this will pull the one furthest in tighter. Just do a little bit at a time and eventually they will be in the right place. If you get the hang of it you can tighten one and loosen the other in one.

take care if they are very tight though and maybe hold the vanes near the tube wall to prevent twisting but be careful not to touch the secondary mirror.

[Mr Flibble]

Got it Thanks Moonshane. I needed to use a towel for grip - those little blighters are very stiff.

Secondary holder is now centered. (I made sure the focuser was square to the OTA and now I've put a long M5 bolt through the secondary holder and the laser is now hitting it bang on!)

Next job now is re-attaching the secondary mirror and on with the collimation