Rethinking my collimation.

[LukeSkywatcher]

I've just been reading another thread about collimation and it really has made me rethink just how well i am collimated. I made a colicap out of a telescope dust cap and a corkscrew. As far as i can tell it worked pretty well but what the hell do i know. It could be off by miles. Everything i see down the collicap is PRETTY much centered, but there is room for improvement which will no doubt bring my images into focus better.

What collimation tool should i go for?

My scope is the SW Heritage 130P flextube.

Do i go for a laser collimator or a Cheshire?

Are they essentially the same thing?

Which is better and will suit my scope better?

I really want to get this collimation thing under control.

Help please.

Very much appreciated.

[Doc]

They are totally different. A laser uses a beam to collimate and a cheshire uses crosshairs to collimate.

Lasers especially the cheaper makes can need collimating themself so if you are on a budget I would say buy yourself a proper collicap and a cheshire to collimate your scope.

[Whippy]

IMO, any collimation tool will only get you close. If that's good enough for you then great. Personally, I find doing a star test is really the most reliable way of checking because it's an eyepiece you're looking through, not a collimator.

Tony..

[LukeSkywatcher]

IMO, any collimation tool will only get you close. If that's good enough for you then great. Personally, I find doing a star test is really the most reliable way of checking because it's an eyepiece you're looking through, not a collimator.

Tony..

I dont expect perfection but i would like something to use to get me even close (really get my mirrors aligned) before i do a star check in my EP. Stars in my EP when observing look tack sharp and bright. I'm more worried that i may not be getting the sharpness of image on planets or even the moon as i could/shouldd be.

Doc.................the fact that you say laser collimators themselves need collimating has put me right off them. So i really should be looking at something with cross hairs?

Thats a Cheshire?

So a collicap and Cheshire will both work in conjunction with each other?

I thought it was one of the other.

Now where to get a collicap? I thought FLO sold them but cant find one on the site.

[proflight2000]

Dont loose faith with the lasers, collimation is pretty easy if it needs doing in the first place of course. I used to use the top off a 35mm film cannister to collimate my old explorer, worked a treat.

[Doc]

Don't get me wrong most lasers are great and will be collimated but I have heard and even had a Antares one that went out of collimation. The Hotech is a laser but is over £100 and from what I've heard is collimated guaranteed.

Cheshire are very easy to use and I would get one of these and then as Tony says a star test is then the final part of collimation.

You can't beat a good star test.

[John]

I'd do a star test first - your scope may not be far off good collimation. It's easy to get a bit paranoid about it

[pvaz]

A proper collicap, or cheshire, and a star test can do the job well.

A Hotech is nice, I got one, but IMO you'd get more improvement by getting other items or even a larger aperture scope.

Don't take me wrong, I just mean the hotech is more expensive then your scope and to me it doesn't make much sense to get a collimation tool that costs more then the scope you'll use it in.

Besides, the advantage of the laser colli is to make the process much faster, not necessarily better.

[albedo0.39]

I'm a bit old skool

Measure (mirrors, spiders etc)

Collicap (from FLO - £6)

Good cheshire (the longer the better)

Star Test

and if you are feeling brave...

Star Test using mirrors inherant Coma for final tweak

However, a hotech will be faster and it really does make it a cinch.

Good luck ! (and don't worry)

[adamsp123]

I would get a cheshire collimator - cheap and pretty darn accurate.

OK I have an xmas pressy Hotech and it is brill to use but I still final check with a cheshire.

[proflight2000]

It is a shame to some extents that no one has invented a mirror system for a cheshire, especially in respect of an explorer where you break your neck either reaching to the colimation screws or get fit walking backwards and forwards for the checking. That was where I loved the laser, I could view and adjust at the same time.

But learning to collimate with a cheshire was the pinnacle of my astronomy career, it taught me the principles of the mirrors and how they actually work.

[LukeSkywatcher]

Dont loose faith with the lasers, collimation is pretty easy if it needs doing in the first place of course. I used to use the top off a 35mm film cannister to collimate my old explorer, worked a treat.

I pretty much did the same but i AM no expert.

I'd do a star test first - your scope may not be far off good collimation. It's easy to get a bit paranoid about it

Again i am no expert but when i look into the collicap i made everything is PRETTY much aligned. There IS room for improvement. Yes i agree i am as MOST newbies are...........................paranoid. I thought i had it down but cant hurt to double check.

[LukeSkywatcher]

A proper collicap, or cheshire, and a star test can do the job well.

A Hotech is nice, I got one, but IMO you'd get more improvement by getting other items or even a larger aperture scope.

Don't take me wrong, I just mean the hotech is more expensive then your scope and to me it doesn't make much sense to get a collimation tool that costs more then the scope you'll use it in.

Besides, the advantage of the laser colli is to make the process much faster, not necessarily better.

Thanks pvas (i always enjoy your advice). I had not thought of that. No way am i going to spend cash on an accessory that cost as much as my scope. Good god that is just madness especially if it only makes the process faster but the results no better.

Maybe all i want/need is a cheap laser collimator to put my mind at rest???

I will only see a problem with MY scope the day i look through the EP of a BIGGER scope and see the difference. Thats not very likely to happen any time soon. I'm happy with what i have but am paranoid that i may not be getting the full potential from what i have.

If i buy a cheshire (not my money) and my brain thinks it helps........................that can only be good.

[Astro_Baby]

I'd always choose a Cheshire, nothing to go wrong, simple to use and understand and so many of the collimation woes on forums are down to laser collimators.

A Cheshire is cheap, reliable, simple. When I restarted I thought 'ohhhh lasers - must be more accurate, more scientific etc' in the end I bit the bullet and bought a Cheshire. Easier by far really.

Strangely, on collimation, I found it VERY hard to do my Skywatcher 200 at first and assumed that maybe it was cos my know how was so bad. It always seemed that when I had my old longtube reflector years ago it seemed easy. I just used a collicap back then. Well - readers of the TAL group will know I just acuired an old TAL 1. Its a long, slow refelector and collimation is soooooo easy cos of its long focal length and also because its a speherical mirror even though it can be out by a mile it still works fine.

But in a nutshell - I'd vote Cheshire - shimple eh.

[Chris H]

I don't think a laser collimator or a cheshire would work for the Heritage 130p, the reason is that the top of the flextube is not sturdy enough to support the weight. When you put something long and reasonably heavy into the focuser the weight causes the focuser to move and slightly bends the top of the scope. You would then align the mirrors and remove the laser/cheshire and the scope then returns to its original shape and is no longer collimated. Better of sticking with a colli cap for this scope.

Believe me I have tried a laser, cheshire and colli cap, the cap along with a star test was best.

[yeti monster]

I'm in the cheshire/colli cap camp. I have a cap for the Prinz 84mm, as it has a 0.965" focuser. The cheshire is for 1.25" focusers on the 114mm and 10" SNT. Thus far I am happy with the results I get (star tests ok).

When I get my super dooper EPs I'm likely to get more fussy but I have printed out a good guide from CN for collimating the SNT which has a nice final tweek I'm looking forward to trying.

Having grown up riding old motorcycles, tiny adjustments and faffing about etc. are part of my whole being.

Collimation is fun!

[TopHouse]

You cant beat a camcorder, a laser, a cheshire and a collicap

[pvaz]

I think what we are all trying to say is: The only 100% reliable method is a star test and collimating as you do it, because you are collimating based on the real image that reaches your eye.

If you use a laser, and you put it just a tad off axis on the focuser, or the weight of the laser causes the tube to flex a bit, the result will be slightly off. Beware of cheap laser collis! I read lots of posts of frustrated people cause their laser was off axis and, after using it, the collimation would be completely off.

Don't be too fussy about it, a perfect collimation doesn't make that much of a difference to a decent one. I can only notice a difference when using high mags (over 100x) on Planetary observation.

[Moonshane]

my process is :

use a collimating cap - made from a black film canister with a hole poked through - I drilled this initially and made it too big so I stuck a piece of masking tape over the hole and poked a pin through it. the hole size is now just 1mm which works fine in my scope.

I then use a laser (relatively cheap Revelation Astro one about £35) for the secondary to get the laser dot in the primary donut. if your primary has not dot or donut, then if possible make one (and a darker one seems easier) as it really helps. this laser came perfectly in collimation (checked it using the 'v-block method' but you can also turn it in the focuser I suppose.) and it has three grub screws to easily collimate (as easy as a RDF) if not.

I then take the laser out, put a barlow in and then the laser in the barlow (the barlowed laser method). this spreads the laser and reflects the shadow of the primary donut onto the small viewing screen on the laser. centre the shadow and you have good collimation - allows you to see what you are doing from the back as you collimate - saves a lot of time on a 12" dob - but also more importantly eradicates the issues of slop in the focuser etc.

finally I have a quick look with the Cheshire (actually just a cheapo plastic one that came with my celestron refractor - so very light and may suit your needs if you can get one? - referring to the weight issue) to make sure all is well.

assuming the secondary is centered under the focuser (it usually is) then this whole process takes maybe 5 minutes and I do it just as the scope is put out and check briefly again as it's cooled. based on what I have read you would probably only have to do it every now and again though (every few weeks) with your scope.

then a quick star test if the clouds ever clear.

as others have said, I think people sometimes get carried away with collimation but the better you can get it the better the viewing - I suspect it's a process of diminishing returns though.

at the end I have started taking a photo just to check everything looks ok - my camera lens is pretty much an exact fit for the focuser tube. I think this helps as in the first image, I always though something was not quite right and it seems the secondary was a but out of centre in the focuser. I moved it down the tube a bit, recollimated and it seems a lot better now. I am no expert and others might look at these images and disagree the collimation is OK but it 'looks' a lot better. not had chance to try it yet since making this change. not sure how critical the centering of the secondary in the focuser tube is.

I'll still do a star test though.

sorry I have waffled on a bit. I am learning too so we're in the same club!