collimation in progress

[star_chaser]

hi all im going through atsro babys collimation tutorial and staring with the secondary mirror i think this may be off. i have added a pic for some help as astro babys tutorial is very good there is nothing like someone looking over your shoulder giving advice. i thought i had this done once but checking again i think not.because the cross hairs on the cheshire didn't match up to the spider veins and one of the clips is visible

[edit] one thing im noticing is when i move the focus tube out i can see a gap appear around the top half of the view before the bottom

thanks for looking star

[Doc]

Looking at the photo your primary mirror is not centred exactly below the secondary.

[star_chaser]

:icon_scratch:thanks but going through ab's tutorial again i somehow missed the part where you align the secondary to the primary. not sure how i missed this but i am trying to correct now

how i missed this ? unless i tried to do it after a couple of beers

thanks for the reply star

[edit] "Looking at the photo your primary mirror is not centred exactly below the secondary."

not meaning to sound ignorant or doubt your knowledge but how can you tell with white paper blocking the primary ?

thanks again

[edit again] now everything seems to line up except the cross hairs on the chesire its a little low and to the left what would cause this step1 or step 2. as i feel i got step 2 more correct than step 1:icon_scratch: tho its better than before.the reflection of cross hairs is spot on just not the actual ones

[Porl]

did you manage to get it collimated perfectly Star_Chaser? I tried collimating my astromaster 130eq a few weekends ago and I had the same view as your photo, the secondary mirror not being exactly centered under the focuser.

I've had the 3 clips all in view once but the secondary mirror wasnt perfectly centered so i tinkered a bit more and now they've gone. I did a star check and got it back to how it was I think but still get a diffraction spike coming out of once side of really bright stars. Do you get these too?

If you have anymore info on how you got on that would be cool

[beamer3.6m]

Buy a laser collimator, saves all this hasle.

They are very easy to use as you just follow the laser beam and you can easily do the whole job in 5 minutes, even as a complete beginner to collimation like me.

[star_chaser]

did you manage to get it collimated perfectly Star_Chaser? I tried collimating my astromaster 130eq a few weekends ago and I had the same view as your photo, the secondary mirror not being exactly centered under the focuser.

I've had the 3 clips all in view once but the secondary mirror wasnt perfectly centered so i tinkered a bit more and now they've gone. I did a star check and got it back to how it was I think but still get a diffraction spike coming out of once side of really bright stars. Do you get these too?

If you have anymore info on how you got on that would be cool

well i left mine (the secondary)as it apears in the pic but all cross hairs do not match up exactly(with cheshire but they are a lot closer than before)) so im guessing its still a bit out. but its better than it was and as it took so long i decided to leave for now. also the primary clips were not exactly comming into view at the same time (when moving focus tube in and out) but i found this very hard to get right and it also took a while i left for now also altho it was very close

i have done a star test but didnt see the circles but got the doughnut effect and appeared to be centre so im happy for now

im not sure if you used abs tutorial but if not give it a try if you have allready just start again if your not happy. but give yourself plenty of time so there is no need to rush i took about 4 hours with a few tea breaks

sorry i cannot be of any more help but i still get worried when setting up that it has become uncollimated and i have to do it again

good luck you will get it sorted just take your time. star

[edit] looks like the spider viens on the cheshire do not have to match up precisley so maybe i did a better job then i thought. tho my secondary is to the left a little looking again so looks like im gonna have to do it again also

[Porl]

thanks for the reply Star_Chaser Yeah I used AB's collimation guide. Hit a snag straight away with not having any secondary mirror vein adjustment. I had a go over 2 nights and like you got the cross-hairs as close as I could to the vein's and similar with the clips.

With the nights staying light until pretty late ( i was out trying to test my scope the other night until 11pm and it was still slightly blue in the sky ) i've not had a proper test yet to see i've left it okay.

I think I will have another tinker at some point, got the cheshire eyepiece so may as well hey.

thanks again for the reply

[banner001]

@star_chaser, that single clip that is visible is part of the secondary mirror, its a little clip that holds the secondary mirror in place, its not part of the primary...

[banner001]

Buy a laser collimator, saves all this hasle.

They are very easy to use as you just follow the laser beam and you can easily do the whole job in 5 minutes, even as a complete beginner to collimation like me.

who told you this? because they are wrong

a laser collimator should be used once you have used a cheshire collimator to check the final allignment before using a star test.

and unless you have collimated your laser collimator it will be off, you really need to do a barlow laser collimation to eliminate the variables inherent with laser collimation.

but the use of a cheshire in aligning the secondary under the focuser, and adjusting the primary mirror properly cannot be understated!

[TheThing]

who told you this? because they are wrong

a laser collimator should be used once you have used a cheshire collimator to check the final allignment before using a star test.

Nonsense! You CAN use a laser and have the scope collimated in minutes. It's easy to check a laser is collimated and far more are than aren't - one of those urban myths I'm afraid!

Forget A_B's guide - it is overly complicated for what is actaully a very simple procedure. Instead, use Andy's Shot Glass . So much better.

[twotter]

Wouldn't you still need a device of some sort to ensure the secondary is central in the focusser though? A cap or cheshire would have the advantage to a laser then surely?

[TheThing]

Watch Andy's Shot Glass video. You check both the primary and the secondary. In fact, you can do it all with nothing but your eyes!

[twotter]

I have watched it, many times In fact I've tried to follow it and collimate visually a number of times, but never felt totally comfortable.

On Friday I got an Astro Eng Collimate Deluxe cheshire and used that, as well as the video. Just needed a tweak of the primary and everything looks lined up. I even enjoyed doing it, and might get a set of Bob's Knobs, and a laser in future (though partly for my James Bond villain fantasy ).