MY FIRST GO AT COLLIMATION..HELP!!!!

[bcfcciderhead]

Ok, got myself a Skywatcher laser collimator today as i feel my 130P needs doing, not put of by having ago myself as we all must learn, had a quick look by putting the collimator in the focus tube, turned it on and the red dot was way of the targets so yes i guess it does need to be done, ok, lets get to it....umm, i thought the primary had a mark to show the centre? mine has nothing, ok lets try to get the little dot on target by adjusting the primary, after a few mins with the screws at the rear i had it spot on!, no way cant be that easy? then i moved the focuse knob and the dot moved out of the centre, i guess its not that easy.

So my questions are 1. do all primarys have the centre mark on the glass?

2. is the focus knob to be fully out or fully in?

3. with out the centre mark on the primary how do i adjust the secoudary mirror?, i did measure the vanes and they seem an equal distance.

[steppenwolf]

3. with out the centre mark on the primary how do i adjust the secoudary mirror?, i did measure the vanes and they seem an equal distance.

If you are going to collimate with a laser, you will need a centre mark I'm afraid but the good news is that you can apply your own. The popular choice is to use a file hole reinforcer (looks like a small self adhesive paper doughnut!) which you apply to the exact centre of the mount - you need to find this point by removing the mirror cell and VERY carefully measuring the mirror to determine the exact centre.

[peteuplink]

I read in Sky at Night magazine that you can put one of those hoops for reinforcing punched holes in paper in the centre of your primary mirror and then you just line this up with the red dot. However I've never tried tried it as I don't own a telescope yet, so I don't know if it works.

_edit_

Haha Steppenwolf. You must have just beat me to it by mere seconds

[bcfcciderhead]

I have seen that before else where, but was also told that if you hold some white paper up to the scope and you see the red dot hit the paper then yes the secoudary needs to be done, ok understand that, done that with mine and no, just a shadow of the spider vanes, does this mean its not to bad? also on the focus knob question i tried with it fully out and had some play in it, then fully in and solid so i guess fully in?

[Arushin]

Hi,

Yup!

You will need the centre mark on the primary to get accurate collimation. I don't think that it matters whether your focuser is 'in' or 'out' but someone with more experience may correct me.

Adjust the secondary first!

There should be a centre screw in the secondary holder which needs to be loosened SLIGHTLY. You should then be able to make small changes to the mirrors tilt using the 3 smaller screw in the secondary holder.

With my laser I first adjust the secondary mirror so that the laser is direct centre of the primary (this is where the primary centre ring comes in) THEN adjust the primary so that the laser fires straight back into the centre of the collimator.

Hope that makes sense!

Regards Tony

[Astro_Baby]

Centre spotting Cleaning the Telescope Mirrors

The laser may well wobble because (a) The laser may be out of collimation itself and ( the focuser in the 130 does have slop in it which allows the focus tube to wobble. MOst focusers do but you can tune it up a bit.

Tuning up the basic focuser here

Skywatcher Focuser Tune-up

[Jdavies]

This sounds scary, not looking formard to doing mine

[bcfcciderhead]

Thanks guys, Arushin that makes perfect sense, i know the basic's of collimation, thanks to Asto Baby and a few others but never done it, will get some hole things tomorrow and have a go then.

Thanks Astro Baby more great info and links once again, and yes my focuser has a bit of slop in it and of course the calibration of the laser like you said.

Jdavies yes it does sound scary but once you get going and watch a few videos (you tube has loads) and read a few links on it it all makes sense and dont seem that bad (if you got the mark on your mirror) but i had a go and the mirrors move easy and are easy to guide so dont be put of, after all you cant destroy it (i hope lol) and if it does get out of hand i'm sure theres somewhere you can take it to be done

[Astro_Baby]

So long as you are careful (take any jewellry off - and that includes wedding rings), make sure the scope is laying horizontal so if someithing drops off it doesnt fall down the tube and onto the mirror plus you use care and dont tyry to tighten screws until the threads pop theres nothing much you can do to wreck stuff.

Make sure when you loosen anything around the secondary mirror you support it WITHOUT TOUCHING THE MIRROR SURFACE and ont touch the pirmary surface at all you will be fine.

JUst remember your dealing with precision made glass and not the axle off a Ford Escort and you'll be fine.

I always reccomend if your going to mess about with optics get yourself some cotton gloves from Boots - they only cost about a £1 and are well worth the expense. They will last forever and will avoid you having to worry about sweaty mitts on mirrors.

[wils07]

I wish i read the info on the focuser b4 i had a go myself lol.

Anyway i did it with silicone grease as its non sticking or gumming and the difference is unreal well worth doing imho.

[Moonshane]

don't worry about collimation - once you get the hang of it, then it becomes really quick and easy. usually it just involves a small tweak on the primary once it's been done a few times - that's the most vital for collimation but also thankfully the easiest.

you don't have to make a centre spot with a donut but many do. you can also use a small square of pale coloured tape, maybe 1cm square or even triangular. it's not vital as this bit of the mirror is not 'seen' in normal use as it's hidden by the secondary.

one way to find the centre with little chance of damage is to cut a circle of soft paper (like kitchen roll maybe) the same size as your primary mirror. carefully fold this in quarters and snip off the middle 2-3mm or so. this leaves a hole in the middle. unfold it and then back on the primary put a dot in the very centre, remove the paper and then then put the donut carefully over the dot with the dot in the middle. use a sharpie permanent pen and then if your donut ever comes off when washing you still have the dot.

be careful with the donut and get it right as you don't want to be lifting it again.

[Quatermass]

One little thing I found helpful when collimating was to use an old film cannister but one that the bottom half is white plastic with a gray lid. I drilled a tiny hole in the centre of the gray lid. Then I cut the bottom of the tube off with sharp craft knife. And then.. I put it in the eye piece holder all the way down till it butts up against the gray lid with the hole in it. And then.. pull it back out a tiny amount and shine a red led torch at the side where the white plastic of the tube is exposed. This really helps to illuminate inside so you can see very clearly when the primary mirror dot is lined up. I was struggling to see it all before but shining the red led light at the side works great. I worked hard to get my collimation right and it really helps a great deal and improves the view in the eye piece big time. ohh I want a laser collimation tool as well have fun...

[bcfcciderhead]

Thanks for all the help guys, will do this tomorrow and let you know the result

[Moonshane]

good luck - go carefully and slowly - don't forget your scope will be top heavy when you take out the mirror (if you do).

[Skybrowser]

Be careful when first collimating. Make sure the scope is horizontal and DON'T look down the tube. If the mirrors are way out the reflected laser will come out of the cope and right into your eye. Hold your hand up to see if the laser light is escaping before doing anything. Then proceed as above - secondary first, then primary.

My first go took about 45 minutes! Now it takes less than two minutes!

[peteftm]

Collimated mine first time today with a skywatcher laser and managed ok.I think , by reading a lot of the posts on here, a lot of valuable stargazing is lost due to worrying about this issue :-) To be honest i don't think i'd notice if mine wasn't 100% tuned anyway

[bcfcciderhead]

Well i think i done it.....removed the primary mirror and using a template from "catseyecollimation.com" found the centre, put on a sticky hole thingy (coloured black) so far so good, replaced mirror and set about the secoudary, oh before this i removed the focuser tube and added a new strip to take out the "slop" dont know what they use but i used a piece of velcro, the fluffy part and now it moves much better and with no movement..thanks to Astro Baby for that, well all of it really.

Ok back to the secoudary,had a look down the focuser and all seemed ok, i could see the 3 primary mirror holders and everything looks square to itself, i believe this is correct?, with the laser inserted it was a few mill out so adjusted this by using the 3 small alan key bolts on the spiders, got this spot on centre with focuser fully in and out, so i guess the secoudary mirror is done.

The primary was way out, but i did remove it, this i thought was easy to do, loosen the screws that hold the mirror in place and then adjust with the other screws, took about 15mins but got the red dot centre of the target, tighten back up and alls good, checked secoudary once more and still ok.

So i guess thats it, took about 45mins to do the two mirrors but really was'nt that hard should be quicker next time....just hope i done it right

[yeti monster]

Ah, the joys of taking your new toys apart! Good luck, once done you'll wonder what all the fuss was about.

[Moonshane]

sounds like you got it spot on mate. make sure you don't tighten the primary 'locking bolts' too much as they can cause astigmatism in the mirror (not permanent damage or anything but defeats the object of collimation). personally, I have removed all the primary locking bolts from any scope I have owned.