Collimating a New Scope

[Crater101]

Folks;

I've recently purchased an entry-level telescope at the request of a mate for his son, who may - or may not - go on with the hobby. I'd like to hand it over properly collimated, but my experience has been with SCT's / Mak-Cassegrains / Refractors, and this is a Newtonian. I'm looking for hint's and tips from any old hands out there.

The unit is a Meade (I know, I know...) Polaris 114mm, which I picked up from one of the advertisers here on special.

While no doubt YouTube would tell me a lot about what I want to know, I'm just looking for anything particular to keep a lookout for. I have a Baader Laser Colli Mk III, and the 'scope will only be used for observations.

Cheers!

[Leo.G]

For most young folk get it as close as possible and leave it at that but even better as I did with a friend, I purchased a cheap collimator for her sons 130 Newt and taught him how to use it. When I use my 8" GSO f5 Newt I set it up before dark and always double check and tweak it (if necessary) before I start trying to image, it's not a hard procedure.

I think the majority of smaller units like the later 127 Newts from Celestron aren't that adjustable but I may be very wrong on that count.
Just the cheap washer type collimator and a good torch does the trick with what I play with, no great degree of accuracy but the primary is spotted and my son has great eyesight (me not so much so I always get him to help).
One day I have to do my RC8 and from what I've read that thought has me very scared, I'd just rather not use it at the moment.

[Leo.G]

Sorry, one tip I forgot to mention, often the scopes with cheaper focusers have a bit of slp in the fit of eyepieces and hence the collimator. I tend to rotate the collimator to make sure it is centres in the cheaper focusers, you will notice the difference rotating the thing. I then try to obtain an average throughout the rotation so it's reasonably close.
If the primary isn't spotted for easy collimation you can print out templates to apply a centre spot to the primary itself and while a dot from a marker (check which won't affect the coating first, I believe some may) I like the old loose leaf binder rings still available from many newsagents. Whether you do the alignment and they call you if it's out or you teach your friends son how to do it with, the centre ring it's extremely simple to pick up on the inaccuracy of the focuser lock and basic focuser slop and if rotating the washer type collimator maintains the spot within the centre circle collimation is fine for visual.

I wouldn't say this with high end gear but for a kid, even just seeing the moon craters is going to blow his mind.


School holidays here and if weather permits I must take my 8" Newt or RC over to an associates place (10 year old kid with 130 Newt) and my guided mount and give him a look. I've promised a few lots of holidays I'd try but weather and health have been against me and he's partially lost interest, I may be able to change that again since his parents spent a lot of money (for his age) to get him set up (same kid).

[Startrek]

Here’s a basic guide that’s good enough for visual use ……

Collimating a Newtonian Reflector Telescope

Tools needed
Cheshire collimating 1.25mm eye piece
Laser collimator eg: Orion LaserMate Mk 2
Allen key or Phillips head screwdriver

Collimation is the process of aligning the telescope optics ( secondary mirror and primary mirror ) to the central point of the telescopes focuser. Light enters the telescope opening , reflects off the rear primary mirror to the front secondary mirror and then directed up the focuser tube to an eye piece or camera sensor.
It is important to accurately align the optical system in a Newtonian Reflector telescope to ensure the reflected image ( eg: Star ) is precise and not distorted in any way once it is focused. Both Secondary mirror and Primary mirror have 3 adjustment screws for 3 points of adjustment.
Secondary mirror can be adjusted for tilt, rotation and longitudinal adjustment
Primary mirror can be adjusted for tilt in 3 planes.
The Secondary mirror is adjusted first followed by the Primary mirror last.

Step 1 - Remove all lids and covers from telescope. Place the laser collimator fully home into the focuser with its bulls eye target cut away section facing square to the rear end of the telescope or towards the big Primary mirror and tighten up focuser grub screws. Switch on laser collimator.

Step 2 - Adjust the small Secondary Mirror using the 3 secondary mirror or front adjustment screws ( normally Phillips head ) on the front of the telescope until the red laser dot is precisely in the centre of the big Primary Mirror’s tiny white donut central target. This takes some practice to get it centered. Once centered leave the laser collimator switched on.

Step 3 - Now go to the rear of the telescope and look along the telescope to the focuser and the laser bullseye target of the laser collimator.
Ideally you do not want to see a laser red dot in the collimators bullseye target, instead you want to see just a faint even red glow of the laser around the bullseye target central small black hole. To adjust , loosen the 3 Primary mirror locking knobs ( anticlockwise a few turns ) and then adjust the other 3 Primary mirror collimation adjustment knobs to achieve an even red laser glow around the central bullseye target and small central black hole.Once adjusted as best as possible, carefully and lightly tighten up ( just a bit ) the 3 Primary mirror locking knobs. You may have to check the even red laser glow again as it may have moved slightly as a result of tightening up the 3 locking screws. This also takes some practice.

Step 4 - Go to the front of the telescope again and check to make sure the Secondary Mirror collimation adjustment still has the laser dot centered precisely in the centre of the big Primary mirror’s tiny white donut marker.

Step 5 - Once satisfied both Secondary and Primary mirrors are collimated correctly, switch off the laser and remove from focuser. Your telescope is now Collimated ready for use.

NB: You can also use a Cheshire 1.25mm collimation eye piece in the focuser to double check the laser collimation adjustments.

This site is also very popular for first time owners of Newtonians …..,

https://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/

Cheers
Martin

[Crater101]

Gents, thank you very much indeed. It's greatly appreciated. After that, if I can't get it right then any issues are purely my fault.

I am not worthy! :thanx: