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Secondary mirror out :(


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How does one go about lining up the secondary mirror?

The reflection of the primary mirror is no longer in the centre. You can see the little tabs that hold the secondary in place though the Collimation EP.

I think my brother grabbed the Spider las night when he was helping me carrying the scope in.

A Mega PO'd Kain

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I think my brother grabbed the Spider las night when he was helping me carrying the scope in

Ouch!

Don't panic mate it will go back right :)

Check the spider, is it bent in any way?

If not, using the three small screws at the front of the spider you have

to tweak it so that the reflection of the primary is in line with the focuser.

These screws push against each other so you may have to loosen one and tighten another.

*BE CAREFUL* lower the front of the scope downwards so that if you drop a screwdriver it

won't slide down the tube and whack the primary

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The 3 screws that stick out the top moves the reflection of my eye around, is this right? The elliptical secondary mirror doesn't quite look round anymore and the reflection in that mirror of the primary is abit off the secondary when you look down the focuser. The spider was slightly bent, but I have corrected that.

I can't figure this out, and looking at the guides only make me more confused!

I want to murder my brother..

Kain

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If the secondary doesn't look round then it's probably twisted round on it's axis a bit

which makes it look oval.

Slightly loosen the three screws and you should be able to turn the whole secondary

unit about it's axis till it looks round again.

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Ok I have finally lined up the focuser with the secondary, and collimated the Primary using the Cheshire.

Now how do I line my reflection of my eyeball up.

Although this is still fiddly, doesn't seen half as stressful as last time :)

Kain

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It looks to me like the primary looks fine but the secondary needs a tweak. Use the 3 screws to centre the secondary until you get a perfect circle in the middle. (That's what I would do but somebody second that as I'm no collimation expert!)

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The first picture looks like the secondary got rotated around the 'scope axis as Phil. suggested, happens all the time with my Skelescope, you just need to carefully turn it back until it looks circular through the focuser. Second picture looks a lot better, though I'm used to a laser and don't know what I'm looking at WRT the middle part of the picture.

Captain Chaos

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Hey CC

In the picture, the bit where you look down the focuser and you see your eyeball, well its not lined up. If I move the screws on the secondary, it throws the reflection of the primary off centre.

Now sure how else to explain it really :insects1:

Kain

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I think my brother grabbed the Spider las night when he was helping me carrying the scope in.

Your brother has been at it again? You need to keep him away from your scopes! :)

Lol I know, mind you feeling unwell last night, I was thankful he helped me carry it indoors. I did tell him not to touch the spider, and showed him where to hold, but it seems I was talking to a brick wall!

Still I suppose it was going to happen someday, so it's all experience on how to correct the problems.

Kain

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Kain

Once you get the reflection of the primary dead centre under the focuser and

the secondary looking circular through the focuser then the job at the secondary

end is pretty much done,

Everything else then needs to be lined up with the primary centre spot by using

the primary mirror collimation bolts.

If you try collimating by going back and forwards between primary and secondary

tweaking, it will end in tears.

Break it down into two distinct and seperate jobs mate

Good luck :)

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How do you get the reflection of your eyeball in the centre though? Its off centre, everything else seems straight!

I really don't know how to explain it..This damn scope is starting to wind me up abit now. It's the last time I ever ask for a hand in carrying it back indoors..

Kain

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Yeah step back and shove the thing so far up my bros backside he will see M78 with his own eyeballs!

I wonder if theres any place that collimates these things for a small charge, it would save me going grey before I'm 25!

I used to have shoulder length hair, but after this morning antics i'm bald! (well not really, but felt like ripping my hair out!)

Maybe have another go when I ain't feeling so under the weather.

Kain

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When you are adjust ing the secondary, concetrate on getting the image of the primary mirror centred in the secondary, and ignore what you see in the primary.

Once you have the image of the primary centred in the secondary, move to the primary, and get the reflection of your eye, or the crosshairs of the collimator, centred by moving the primary mirror adjusting screws.

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