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Hi, I'm in the middle of collimating my Newtonian for the the first time, and I think I know what I'm doing but I have one question. When I put the laser in the focuser do I need to tighten the focuser screws to hold it in place as I would an eyepiece? The laser dot seems to move slightly depending on wether it's loose or tightened. What do you think?

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I use a Cheshire personally, but I would usually recommend you put whatever tool you use into the focuser as you would an eyepiece. also, have the focuser racked out to about the usual position of focus. good luck - you'll wonder what all the fuss was about in a few years minutes :grin: never panic. if you can adjust it wrong, you can adjust it right too.

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You need to tighten the laser as you would an eyepiece, but as you have found, it will still rock in the focuser. I use a laser but with a Barlow which eliminates this problem. If you search for the Barlowed laser technique this will explain it.

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I've watched that video a few times, still not done mine for the first time yet.

I'm sure I heard or was told that the laser should fit snug in the EP holder, if it doesn't some even tape around it should be better to tighten it up.

Why do that?

Well I bought the laser the other day, thought I would stick it in the EP to take a look (not helpful I don't have a center spot on the primary) but with my scope the EP holder has two thumb screws. Now depending on which you tighten or nearly tighten first the laser seems to be in a different position. So I can understand why make the laser fully central to the EP holder.

I'm sure someone will come along and correct me.

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Well I broke it. Awesome. The secondry mirror fell off and hit the primary. The secondry now has a chip on the edge, and I can't tell if the primary's been damaged. Well and truly cheesed off.

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Owch, that hurts.

Hopefully you will have got away with it.

For a 'standard' secondary colimation you really shouldn't need to unscrew the center screw at all.

Watch a shed load of tutorials before trying to put it back together.

Rich

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sorry to hear that. I must admit I almost added something about safety but given your comments didn't want to offend.

all is not lost though. if the face of the secondary still reflects all of the primary then you should be fine. I'd recommend the following:

carefully take out the secondary and paint any damaged edges with matt black

if the primary is chipped anywhere then do the same

the above with create no impact on the images at the eyepiece and although the onsale value is undoubtedly reduced you'll still have a usable telescope.

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Hope everything is ok.as for collimation a simple colli cap to collimate the secondary then replace the colli cap with a barlow and laser inserted into the barlow then adjust the primary mirror

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  • 4 weeks later...

Thanks for the reply's, I've since put it back together and used it, after collimation. It's seems fine after colouring the chip with black marker. The views I've had since are similer if not better after the collimation. so all's well!

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I'm glad all is well after the mishap!

The focuser question is a good one. It's not often mention in collimation guides and took me a few time to realise that the order you tighten the screws does matter. I hadn't thought about it before and wasn't particularly bothered which screw I tightened first whilst observing. Now I always tighten them in the same way. You can get tidy adapters that tighten in a uniform fashion however!

Cheers

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One thing with a laser is to make sure you mark both it and a where it is when you place it in the tube so to speak, this is to make sure that you are hitting the same spot each time. The reason for this is that lasers themselves need to be collimated as well from time to time, it isnt a difficult process but making sure it is in the same place each time will tell you if there is a marked difference. Glad your newt was ok, the main thing is, at least you are having a go.

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cuivenion........I have the gen 2 laser like yours, and use this method of setup. (www.youtube.com/watch?v=bE09_X43UUQ ) works for me, although I used a few more 'T'- pieces so ensure a more rigid jig. One thing to note, one of my adjusters doesn't stop! it just keeps screwing, must be thread bare? But at about 18 feet, my laser dot stays perfectly centre whilst rotating the laser tool.

Edited by Charic
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Collimating lasers can be a right pain... and even when they are collimated there is slop in the focusser to contend with.a simple colli cap for the secondary would do the job just fine...and a laser( dont matter if collimated or not) and a barlow for the primary mirror

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I have read about the barlowed technique, I'll have to give it a go. I can make a simple colli cap out of the focuser cap can't I.

Yes.......centre drill a small hole. Mine was 0.5mm but  I'm sure I enlarged it  to 2mm.

When you Barlow the Laser, it doesn't matter about a sloppy, loose fit. The Barlow diffuses the laser beam. What you see is a circular reflection of the centre spot around the hole where the laser beam exits the tool.  Just centre the shadow around the hole, job done!

Note: Barlowed laser is to set the primary mirror only.

Edited by Charic
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