SW 130PDS Collimation advice

[Maho]

Hi all

 

Not wanting to hijack someone elses post regarding their collimation issues with their 200P, I have an issue with my telescope.

I'm a complete newbie and have only received my  first scope this week. When I put the laser collimator in, the red laser dot on the primary mirror is off by quite a bit from the middle circle. When I try to adjust the primary mirror with the knobs at the back of the scope, the red dot barely moves an inch, of at all. Does this mean I have issues with my secondary mirror? The spider is very stiff, and the screw in the middle wont budge at all, and I dont want to push too hard incase I damage it. I will be getting allen keys tomorrow if the issue is with my secondary.

I have attached pics for reference and the target on the collimator (which is blurry).

Any advice would be most helpful.

 

many thanks

Maho

[Jamgood]

I'm new to this myself with the same scope. Firstly I'd say, don't touch the secondary mirror unless you're absolutely sure you have to. I had no choice but to adjust mine and it was a nightmare as a newbie.

Is your laser collimated? Mine was off by a long way. Watch this.....

 

Others will be along with better advice soon.

[Aramcheck]

@Jamgood beat me to it... I agree - it could likely be that the laser alignment itself is out.

I find basic collimation easier just using an alignment cap & the procedure given here:-

http://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/

That said, the three SW OTA's we've had from FLO didn't really need any adjustment for a long time after purchase...

Cheers
Ivor

[Avocette]

Another video from Dion from Astronomy Shed points out that ‘a laser collimator can lie’ and you shouldn’t adjust the secondary mirror trying to get the spot into the centre of the primary mirror’ (too many adjustment variables). The video is actually about aligning the secondary using a webcam, but you can usually do quite well enough if it’s out of collimation with a Cheshire or collimating cap.

 

 

[Maho]

Thanks for the tips everyone. So I've scrapped the laser collimation route and did a collimation cap, which I think works better. My issue seems to be that when I look through the collimation cap, I only see only a portion of the mirror rather than the whole mirror. I do use the alligning screws on the back of the scope but it doesnt show the whole primary mirror.

 

Is this normal? I've attacked pics I took through the hole of the collimation cap.

 

 

[Ricochet]

Your secondary needs adjusting. I think that you should buy a proper Cheshire/sight tube to do this. You need to adjust the secondary so that when you look through the Cheshire the doughnut on the primary mirror coincides with the crosshairs. 

[Pixies]

Follow Astro Baby's guide - and check steps 2 and 3.
http://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/

It looks like the secondary needs adjusting. If you only have a collimation cap, you can still get close.

A laser is OK for adjusting the primary, as long as you are certain it is collimated itself. But for the secondary, it can be a bit hit-and-miss