Collimation Help!

[Nick-In-Ireland]

Hi,

I received a Skywatcher Heritage 130p from FLO + a Celestron 2x barlow and 2 Vixen NPL Eyepieces a few days before xmas, the secondary mirror mount was swinging loose, not good.

I set about collimating the scope with a home made 35mm film canister coli cap, which is all i have, the pic shows the best i have got it so far :-

You can see things a lot better when you take a pic, i now see that the primary mirror doughnut is not centered with the colicap but that's just a primary mirror tweak.

The bit i am having trouble with is the secondary mirror positioning, could you give me some help as to what needs to be done and what i need to do to fix it, also my offset look too much, but that was set automatically when i used the guide below :-

http://www.garyseronik.com/?q=node/169

Any help appreciated.

Nick.

[almcl]

I am far from being an expert but your secondary mirror doesn't appear to be centred in the view of the eyepiece tube.  You could check this by measuring the distance to the middle and adjusting so that the centre of the secondary support is equidistant from the tube sides?  

[Dannae]

Hi Nick,

I agree with almcl in that you need to adjust your secondary. 2 ways:

1. Loosen/tighten opposing spider vane tensioners to 'pull' the secondary 'up' a touch in your picture (it will be a side to side tension screw/bolt that needs to be adjusted). This will centre the secondary in your focusser left to right (or up and down in your pic).
2. Loosen the centre screw (with the scope horizontal or thereabouts!) or the secondary and drop it down a little way to centre it up and down in the focusser (left and right in your pic). Tighten up again.

You may need to check the swivel on the secondary later to get it fully facing the focusser but it looks fine to me at the moment in that the full face seems to be illuminated.

If you have marked an offset on your secondary (I would be amazed there would be enough to tell or measure on such a small secondary! then you should end up with concentric circles ultimately that coincide with your spider vanes. I never bothered offsetting on my 'large' 72mm secondary so I am always used to seeing offset (but concentric interior secondary mirror) reflections that don't quite match with the vanes but are still perfectly in collimation.

This is also a good site to check and she is a very knowledgeable member here:

http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

Hope this helps.

Regards

Dannae

[Dannae]

Hi Nick,

I agree with almcl in that you need to adjust your secondary. 2 ways:

1. Loosen/tighten opposing spider vane tensioners to 'pull' the secondary 'up' a touch in your picture (it will be a side to side tension screw/bolt that needs to be adjusted). This will centre the secondary in your focusser left to right (or up and down in your pic).
2. Loosen the centre screw (with the scope horizontal or thereabouts!) or the secondary and drop it down a little way to centre it up and down in the focusser (left and right in your pic). Tighten up again.

[RichM63]

Measuring can be a bit of a pain.

Fortunately a guy in OZ came upwith AlsCollimationAid. It allows you to set concentric circles + center over any on screen image.

AlsCollAidV11.zip

[crimbo2047]

I have just got the Same scope

I put a piece of paper across the lower part of the tube (you have the flexi tube?)

Then I used a sight tube with cross-hairs to centre the secondary. After that a Cheshire eye piece for the primary

It improved the contrast for Jupiter

I think FLO do a Cheshire with cross-hairs

[LukeSkywatcher]

I honestly think FLO (or the people who make this scope) leave the secondary mirror arm slightly loose so it doesnt bend/break while scope is in transit. So many people here report that the secondary arm (spider vane) is loose. Mine was loose also and i just twisted it by hand a little and then did collimation (as best i knew how). I would guess my collimation is 95%+ and ive never had an issue with observing. Everything seems clear and sharp. Ive had the scope since quite soon after it was released and only ever collimated it once. 

You dont look like you are far off, just a couple of tweaks to the right, or is that left?.

P.S.~~~collimation has be discussed over and over and over here on SGL, but that's good because it is something that people are terrified about doing the first time. You can never mess up your scope by doing it and it takes 2,3,4 times to get it right. 

All you are doing is aligning the primary and secondary mirror so everything is perfectly centred (or as close as) in the tube scope. Its more important if you do astro imaging to get it as close to 100% spot on. For visual astronomy (as this scope is designed for)............you dont need it as close to perfect.

[Nick-In-Ireland]

Thanks for you prompt help every 1, yes i have the flex tube crimbo2047, shame it has no spider vanes it would make collimating much easier.

That's a great little util richM63, its an OCD collimators wed dream LOL  and of course a v. useful util, as u can see from the pic and as ppl said above, i need to be up and towards the primary.

[Nick-In-Ireland]

Forgot to say in the last post, if any1 is having trouble getting the red dot finder to not go low enough like i did the the simple solution is to shim then with sucker sticks, i have plenty of travel now, when i have sorted the collimation out i will of course trim them down and colour them with a black marker.

[LukeSkywatcher]

Forgot to say in the last post, if any1 is having trouble getting the red dot finder to not go low enough like i did the the simple solution is to shim then with sucker sticks, i have plenty of travel now, when i have sorted the collimation out i will of course trim them down and colour them with a black marker.

DSCF8258_resize.JPG

DSCF8259_resize.JPG

That last image with the wooden wedge in the RDF and the bent flex tube screw looks very wrong. No reason for either to be like that.

[Nick-In-Ireland]

I never noticed that flex tube screw was like that when the scope is closed, i will take a look cos it looks wrong in the pic like u say, but without the shims i cant line up the red dot to the target, it just wont go low enough, i have read that other ppl have this problem too with this scope and this is my zero cost fix.

Here is another zero cost fix, a free eyepiece case made from a food container (don't tell the woman ;-D ) and the foam that came with the scope! not a future proof case i know but it will do for now.

[Dave In Vermont]

Measuring can be a bit of a pain.

Fortunately a guy in OZ came upwith AlsCollimationAid. It allows you to set concentric circles + center over any on screen image.

Capture_+Mire overlay.JPG

This looks to be very fine toy! Thanks for posting it!

Anywho - I often add my 2-p to collimation queries. For now I'll just add this: Once you have (finally) collimated your scope for the first time, it will become easy next time, and easier and easier in an exponential dropoff of being a nuisance. In fact - I rather enjoy it now! So hang in there, and don't get too technical. A Cheshire sighting-tube and/or a laser will help. The final thing is an outdoor star-test. That's the real way to be certain.

Clear & Sharp Skies,

Dave

[Nick-In-Ireland]

This is about as good as i can get it with a collimation cap, is this plenty good enough for visual astronomy ?

[Dannae]

That's a world of difference Nick Well done!

What you need to do now is star test the telescope. With a relatively bright star (Capella in Auriga, Rigel in Orion) with your lowest focal length eyepiece (highest magnification) defocus the star until you see the diffraction rings which should be concentric if you are in perfect collimation. You can defocus either side of focus to double check but you will need to let the optics cool down to ambient to get a steady view.

Regards

Dannae

[Nick-In-Ireland]

Thanks, i tried the star test last night but the seeing was so bad, it was hard to make out the deftaction rings even after cooling, i will keep at it though cos the star test is the ultimate test as they say & the seeing changes night to night, i used this excelent guide:-

http://www.garyseronik.com/?q=node/238

[RichM63]

Yup, OCD Collimation is certainly an affliction LOL. Worry when you start to magnify to 400% and start to use CS4 to count radius pixels!

As per, now for a Star Test, but you should see a great improvement, and certainly will no longer doubt your abilities.

[crimbo2047]

Looks good Nick Now go and enjoy using it

[Nick-In-Ireland]

In the book "The Backyard Astronomer’s Guide, Third Edition" its says to use a camel hair brush to remove fine dust and debris from your

optics, i know it is not good practice to clean your optics often so i wont, the secondary mirror on a newt needs the occasional waft with

a brush now and again, i just wondered what you guys use and where did you get it from?

[NoSiriusly]

Measuring can be a bit of a pain.

Fortunately a guy in OZ came upwith AlsCollimationAid. It allows you to set concentric circles + center over any on screen image.

Capture_+Mire overlay.JPG

Just tried this on my scope. What a great yet simple tool. Turns out that I have a fairly good eye as it seems to line up quite well. That was with a colli cap and cheshire. 

[happy-kat]

Going to try this on mine too, don't have a good enough image to use yet, slight feeling of tripidation but head sand and all that wont do.

[ddtwelve12]

ive used this from youtube http://youtu.be/jcL37RJuVyQ

uses your mobile camera to align your secondary ingenious way and it works I get nice airy discs now