Laser collimator for skywatcher skyliner 200P?

[Coastliner]

Hi,

I have one of the above scopes and have read Astrobaby's guide to collimating it (an excellent article, it must be said).

I would like to give a laser collimator a go and understand that some of them can "slop" around so much in the focuser that they are practically useless. I also understand that the collimator itself may need collimating, I am happy with that.

Does anyone know of a decent collimator (laser) that works well and accurately with the 200P? I have had a look on Amazon and see there are plenty to choose from!

Thanks,

Neil.

[Lowen22]

I would be interested to find out too… I have one but it doesn't seem to work that well. Either that or I'm doing something wrong. How have you found the 200p so far?

[Coastliner]

I like it, but I'd like to make life a little easier when it comes to collimating.  You might like to look at this:

-using a laser collimator.

[LMC]

Good vid.
I can recommend the 'Howie Glatter' laser collimators.  They aren't cheap, but are very well made and in my SW 300  showed no signs of slipping or slopping.  Takes maybe 2 minutes including ciggy break.
Well worth the money, IMHO, especially if you move the scope around a lot.

PS-I don't work for nor have I met Howie Glatter.  It's just nice when something does what it says on the tin.
 

[lensman57]

Hi,

I have one of the above scopes and have read Astrobaby's guide to collimating it (an excellent article, it must be said).

I would like to give a laser collimator a go and understand that some of them can "slop" around so much in the focuser that they are practically useless. I also understand that the collimator itself may need collimating, I am happy with that.

Does anyone know of a decent collimator (laser) that works well and accurately with the 200P? I have had a look on Amazon and see there are plenty to choose from!

Thanks,

Neil.

Hi Neil,

I use the Baader laser collimator not cheap but  good stuff hardly are. It is very well made, collimated at the factory  so you don't need to mess with it and highly accurate. The Fresnel screen is not however suitable for the Barlow method of collimation. As with all laser collimators it only collimates the primary and not the secondary that has to be centred  before you do the primary.

A.G

[triton1]

I use a cheap laser collimator which I had to collimate and then applied a single layer of masking tape around the barrel no slop at all

[Coastliner]

Thanks AG, interesting you say that you can't use the laser to collimate the secondary - the above vid shows him doing the primary and the secondary. Am I missing something?

[Coastliner]

Jonn - your sig - modded and flocked? Can you point me to the mods?

[Scooot]

Thanks AG, interesting you say that you can't use the laser to collimate the secondary - the above vid shows him doing the primary and the secondary. Am I missing something?

You can't use a laser to centre the mirror in the focuser or to check that it looks round. However once this is done you can use it to tilt the secondary accurately so the laser points at the centre of the primary, which is all that needs doing after everything is originally set up.

[Coastliner]

You can't use a laser to centre the mirror in the focuser or to check that it looks round. However once this is done you can use it to tilt the secondary accurately so the laser points at the centre of the primary, which is all that needs doing after everything is originally set up.

...plus then aligning the primary so that it reflects the beam back along itself to the secondary, up the tube to the laser target on the collimator? (I'm not trying to be smart here, just making sure I have it right in my brain. Or brain cell).  Agreed and understood re the up/down position and rotation though.

I may well re-visit Astrobaby, as I've been doing a bit of research today and may be getting it finally.  It's trying to reconcile the diagrams to what I'm actually seeing that's the problem, but if all else fails I will be looking for an accurate laser.

Many thanks for all the help so far!

[triton1]

I put a washer with three dimples on it behind the secondary mirror so the collimation screws locate in these.Stop the secondary holder from getting scratched by the screws so collimation is easier.Where the focuser bar meets the draw tube filed that so it's flat so the bar is in full contact to improve focusing,also replaced primary mirror screws with Allen key screws so no danger if slipping when removing mirror for cleaning

[lensman57]

Thanks AG, interesting you say that you can't use the laser to collimate the secondary - the above vid shows him doing the primary and the secondary. Am I missing something?

The secondary mirror centring can not be done with a laser I am afraid. For this you need a combination Cheshire collimator. Once done then the laser can be used to fine tune  the secondary tilt and the primary collimation. This is also an  iterative process so a couple of cycles are required at least. personally I find the centring of the secondary and the orthogonality of the focuser to the optical train a right royal pain as these are critical for imaging. If you just want to observe then life is a little easier.

Regards,

A.G

[Jason D]

A laser can be used to center the secondary but it will need to be used with a holographic attachment. Glatter laser collimators support holographic attachment. Below is an example of one method. A template is attached to the inside of the focuser.

Jason

[Charic]

Having owned both, I would recommend a combination Sight Tube / Cheshire for your collimation needs. My laser works well, but needed collimating on arrival. However I use the Barlowed Laser method for checking the collimation of the Primary mirror when out in the field. I wont sell my laser, and it is possible to get good results from just using the laser alone, but the pitfalls and fit of the laser, can cause more problems than solutions, if your not prepared, or fully understand their use and setup.

[laser_jock99]

Don't skimp on the laser collimator. The 1.25" fitting £25 E-bay ones are more or less bin worthy- you get what you pay for sometimes........

I can also recomend the 2" fitting Howie Glatter collimators. Makes collimating an F2.9 Newtonian a breeze......supposedly it doesn't get more 'difficult' than that!

Collimation proceedure....

1) Adjust the secondary so the beam hits the centre of the doughnut on the primary.

2) Adjust the primary so the beam goes back up its own path.

It really is as simple as that.

[Coastliner]

Thanks all, all replies noted and appreciated. I will be borrowing someone's laser on Monday so I will give that a go .

[Coastliner]

Having owned both, I would recommend a combination Sight Tube / Cheshire for your collimation needs. My laser works well, but needed collimating on arrival. However I use the Barlowed Laser method for checking the collimation of the Primary mirror when out in the field. I wont sell my laser, and it is possible to get good results from just using the laser alone, but the pitfalls and fit of the laser, can cause more problems than solutions, if your not prepared, or fully understand their use and setup.

I have one of these http://www.firstlightoptics.com/other-collimation-tools/premium-cheshire-collimating-eyepiece.html

And have used it to set up my scope, I'll give a laser a try and see how it compares.

[Charic]

Coastliner........that's a fine bit of kit and It will allow you to  concentrically align the secondary mirror to the focuser assembly tube (most important ) The Laser alone cannot achieve this task.   Once the secondary is perfectly aligned, you can then use a laser if you want to complete the rest of the collimation, and the videos on-line, show how easy it is. Just be aware that all Lasers are not equal, and spending lots  more, doesn't  always improve the situation. The laser has to be accurately collimated itself, has to fit 100% tight (EVERY TIME) to achieve the same results. There is ample information about the pitfalls if you search for them. 

That tool also has a 'cross-hair' reticule. I for one,  sometimes find it difficult to  focus on this and the central spot  at the same time ( just older eyes?) but don't  confuse the 'cross-hair'  with the 'spider assembly' ( which is  also  seen as a cross?)  the bit that holds the secondary mirror in place, when aligning the mirrors. Ignore the spider assembly. In fact  rotate the Collimation tool. and you'll see the 'cross-hair' rotate, use that as your target guide.

If when you set-up with the laser and all looks good, remove the laser, step away from the telescope, then step forwards and replace the laser ( the stepping is not important - just the removal and replacement of the laser  ) and see if everything is still aligned with the laser dot in exactly the same position +90% chance its moved a little? If you Barlow the laser, and just guide the reflected shadow  concentrically around the laser exit, it will be as good as it gets!

[Ganymede12]

I have a Skyliner 200P dobsonian too and I use the HoTech Laser collimator for the simple reason that I don't have to collimate the collimator itself. I've heard it said that a laser collimator this precise isn't particularly needed for the 200p dob where the focuser isn't of a super-high quality but the ease if use itself is worth the money in my opinion. What this collimator showed me was that about 95% of the time I collimated with the Cheshire collimator, I didn't save too because it was the focuser needing a slight jiggle rather than the mirrors needing a complete re-positioning. I turns out my Chesire colliimator was completely off centre anyway! 

[Charic]

Ganymede12.........it sure says it works!  Getting the laser in a precise repeatable position is the requirement, and I sure can't with mine due to the fit in the focuser. Its the slightest of movement,  caused by the locking bolts on the focuser?

I'm only going from experience using what I already have. And as the info on the site states, the Secondary requires alignment first, which is best achieved with a Cheshire ( or a dust cap/35mm film case ect?)

Any laser collimated or not works well with a Barlow to align the Primary, so don't throw away  the cheap lasers, they can be used successfully in this manner.

[John]

I've owned both the Hotech and Baader laser collimators and found them both to be not collimated themselves, despite the manufacturers claims

I use a low cost laser collimator now that I have collimated to within an inch of it's life !. I tend to use it with a 2x barlow lens and find that quite an accurate method of getting the primary tilt adjusted.

Overall though I find the simple cheshire eyepiece quicker and easier than anything else.

[Coastliner]

Ok, stupid question coming up. If I don't have a laser how do I align the primary when I'm standing in the dark? Do I shine a torch at the Cheshire target area?

[Geordie mc]

I use the Baader. Seems good to me. Never had a problem with it in 2 years of use.

[Charic]

Ok, stupid question coming up. If I don't have a laser how do I align the primary when I'm standing in the dark? Do I shine a torch at the Cheshire target area?

Yes, basically, red light is best.

Best to collimate during the day, and it should be ok for the night, unless its been moved/carried since then.

http://www.garyseronik.com/?q=node/165

[lensman57]

I use the Baader. Seems good to me. Never had a problem with it in 2 years of use.

Me too, I did place it on a precision engineer's v block and rotated it the dot stayed at one spot so it was well collimated at the factory.

A.G