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Hello everyone, 

As a farely new member and astronomer, I've decided to seek help for collimation. 

The task seems pretty daunting at first but I think I got the basics down. 

Unfortunately I cannot find any answers for the questions I have, so here it is: Is it 'normal' to see the focuser's end? 

As you can see in the attached picture (poor quality, let me know if I should do another) we can see a rectangle at the left, the focuser.

I don't think I should be seeing this and I don't know what causes the problem since the secondary 'seems' to be aligned and the doughnut is dead center. 

I'm using a XT10 and the focuser is all the way in. 

Thanks for your precious time, 




Edited by AntoineDemangeat

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Short answer: Yes, - for newtonian scopes only.

A bit more on procedure, - do it all way Out if it hides one of the primary mirror holders (in your case, it will not, as it has 4 holders)

The best option, focus, lock the focuser, and collimate at this point if possible.

P.S. do you use for visual or AP?

asking, as my 130PDS has a focusing pint quite deep way in with my ASI1600MM and Canon, and focuser's tube casted a nasty shadow on the primary,

which caused D shaped stars.

if you use it for visual, - not a problem at all, - it will not have any impact.

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Hello, thanks for your reply! 

I'm using it for visual observations only. Thanks for letting me know, I knew it would have disappeared if I put the focuser out if the way but was intrigued nonetheless! 

Can you develop this a bit more for me :

26 minutes ago, RolandKol said:

The best option, focus, lock the focuser, and collimate at this point if possible.

Do you mean I should find a target first, focus it and then collimate the scope? If yes, what kind of target do you mean? 

Thanks again! 

Edited by AntoineDemangeat

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If you use it for visual,

no much difference to be honest, as super good collimation has benefits for photography only (during long exposures)

In your case, simply during next observing session you can mark your focus with the mostly used EP 

and next time  collimate while focuser is at the focus point. Once done, check the result with full in and full out.

if focuser is good, you probably will not see any difference


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