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First Post, First Collimation


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Hi Everyone.

This is my first post on here. For months now i have been soaking up all the excellent advise offered by other more experienced members. Anyway, i got my first scope about a month ago, had a quick attempt at collimation and after about an hour said sod it and gave up. On Saturday evening i sat down with a glass of wine and studied Astro Babys tutorial in depth. Sunday morning i got up with a slight hangover!, but armed to the teeth with the knowledge

gleaned from the previous evenings swotting. Today was to be the day i would collimate my baby properly. I had bought a cheap Cheshire and a set of Bobs Knobs and was determined to do this upgrade along with the washer trick at back of secondary mirror. The removal of the secondary went without hitch as did the installation of the washer and the thumbscrews. I have posted a couple of pics of the upgrade along with final collimation pics. The entire upgrade and collimation took me about 90 minutes from start to finish. I think i have the collimation as good as i can get it with the cheshire/collicap and i am wondering could it be got any better with a laser? i was thinking of the Baader laser from FLO.

Just want to say a big THANKS to Astro Baby. Couldn't have done it without your guide.

D

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Congratulations! I will use this successful collimation story to inspire my own first collimation experience very soon. I am waiting for my hotech laser collimator which is supposed to be most helpful! Welcome to the forum and now that your scope is perfectly aligned, I wish you clear skies!

Isabelle

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OK, elaborate on the "washer trick" please

Here goes -

A problem occurs when the three collimating screws on the

secondary mirror 'dig in' to the part that the mirror is attached

to. This makes it very hard to rotate the mirror, should that be

necessary, as the end of the screws are in the small pits they

have created.

One solution is to place a large washer (often called a 'repair

washer') between the end of the three screws and the part

the secondary mirror is attached to. When the three screws

dig into the washer, the mirror can rotate, with the washer

sliding on the mirror mount.

You will probably need to slacken the centre screw to allow this.

Assuming the secondary was in the correct place initially, adding

the washer puts the secondary a bit nearer to the primary, so

you need to back off the three screws by the same amount as

the thickness of the washer.

When doing all this, keep the tube horizontal, you don't want to

drop anything onto the primary.

Hope this is clear, if not, please come back for clarification.

Regards, Ed.

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OK, elaborate on the "washer trick" please

Thanks for the welcome evryone.

I read on here that by inserting a hardened steel or milk jug washer between the secondary mirror holder and the thumbscrew adjusters makes collimation of the secondary easier. It allows the secondary mirror to be rotated for fine adjustments while the thumbscrews are lightly contacting the washer. It also stops the thumbscrews digging into the back of the soft secondary mirror holder and causing pit holes. It worked a treat for me. Once i had the mirror all back together, collimation took no longer than 15minutes. I'd say with practice it could be done in 5 minutes as i wont have to touch the secondary again anytime soon. I lost the most sweat making sure i didn't touch the mirror surface!!

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i was thinking of the Baader laser from FLO.

Hi D, I am currently learning the dark art of collimation too and opted for the Baader. It looks pretty sturdy with its all metal design and the documentation covers the basics of aligning the secondary and primary mirrors for newts. There is a section for maks, but cannot comment on how good it is.

Not sure whether this is good or bad, but the collimator cannot be collimated itself, however rotating the colimator 360 degrees in the eyepiece holder showed me that my copy didn't need it. I think they have taken the compression of the thumb screws into consideration as well, as the collimator is marked so that it can oriented in the eye piece holder as they intended.

I cannot compare it to any others as this is the only one I have tried, but hope the info helps.

Edited by palebluedot
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Thanks Lee. I am sort of on the fence as to buy a laser now or not. I have read up some more since and found that they can also be out of collimation!! I will perform a star test the next clear night i get to see how my collimation looks where it matters. If it is reasonably good i don't think i will bother with the laser. I found the Cheshire simple but i suppose the biggest plus for the laser is that it can be used at night in the dark. I'm guessing the laser would also be a faster than the Cheshire to align the mirrors. I did read good things about the Baader one so if i buy it will probably be it.

Decisions Decisions!

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Thanks Lee. I am sort of on the fence as to buy a laser now or not. I have read up some more since and found that they can also be out of collimation!!

it seems the hotech laser doesn't have such problems but it tends in being a little pricey. Mind you with this hobby,.. EVERYTHING can be!

Isabelle

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Hi Isabelle

The Hotech is indeed a lovely piece of kit and i would love one but at £120 its a bit pricey for me. I have 40th birthday coming up in a couple of months so might just have to suggest an extra special gift for that one!! You are right though, this is an expensive hobby!

D

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hi and great news on the colaminate in its a scary job at first i check mine most nights befor a get go in for the night did you do a star test and final tweak or was things fine?stick with the cheshire the laser ones are more easier to use only because you not turning a nut standing to check but with a scope of your size a small eror will not be to badtook me about 5 till a relised a was do in it wrong

cheers pat

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