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collimation 200p newt

jmfdiver

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jmfdiver

jmfdiver

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So I had it all collimated as per videos on astroshed and it all looked good. Lugged everything outside and all I can see are spider vanes. And to top it all I think I have an actual spider in the tube.

I am so fed up.

If there is anyone in the Herne Bay area that knows what they are doing and can show me what I am doing wrong I would appreciate some help.

Jen

:(

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todd8137

todd8137

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all nots lost sounds strange you can only see the vanes did you play about with the secondary ,the bigest mistake is undo in the screw and then turning the allen keys screws you turn one allen key screw and then another all little bits at a time am sure some one wil rescue you

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jmfdiver

jmfdiver

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Yes I've read it about 20 times have the printout in front of me and also did it step by step with astroshed video and it looked right but obviously its not.

I have just ordered a laser collimator so I will see how that goes. I know its probably something stupid but I dont know what. Also I need to look at it tomorrow and see if I can get the spider out and its web.

Jen

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umadog

umadog

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I know it can be frustrating but if we're to help you, you need to be clearer. Can you explain exactly what the problem is? I don't understand what you're trying to get it at by saying "all I can see are spider vanes." You don't tell us what you're doing at the time you see this or what you expect to see.

What do you mean you could see "one of the mirror clips"? Under what circumstances? If the optics are correctly set up I would expect you to be able to see all of the mirror clips.

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damnut

damnut

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Had severe problems when collimating my newt for the first time. In the end took it to RVO who collimated for a tenner!. Best ten quid I spent. When I got it home I marked the pos of each alignment screw with tippex. After that used a 35mm film tube cap with hole drilled in centre..

The vid that The Thing mentioned can be found here :-- Collimating a Newtonian

What a great site Thank You The Thing.

Cheers

Damian

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todd8137

todd8137

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when i took the secondary of to paint it the other day ,i thought i would never get it back to the same as i had it. before you start measure the spider vanes, mine are all 15 cm to the edge of the holder now if yours are say , 15.4 and one is 14.4 ect thats the first thing to do before you start wish i was near you i would pop and see you but miles away its tiny movements at a time

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umadog

umadog

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The astro-baby guide is not over-complicated: it's pretty straightforward and contains important information.

To the OP: if you can't see all three mirror clips then obviously something is wrong. So the problem is that you are physically unable to adjust the secondary in order to bring all of the primary into view? You shouldn't be messing with the primary at this point. What collimation tools are you using (is it a Cheshire/sight-tube combination tool?). Is your problem that the primary mirror seems too big for the secondary? In that case, perhaps the focusser is racked out too far. If none of that helps, can you take a photo through the pupil of your collimating eyepiece?

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jmfdiver

jmfdiver

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I have a cheshire but im using a cap as per ab's instructions. Measured spider vanes, got pieces of card in and secondary mirror central and appearing round. now I cannot get all 3 mirror clips in view using allen keys or slightly twisting center screw. Ive been doing this for nigh on 6 hours now not to mention many previous nights. Racked out is worse so its racked in.

jen

Yes the primary mirror seems to be too big to fit in the view.

Thanks

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umadog

umadog

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First some definitions so we're all on the same page:

A collimation cap is a Cheshire. A "sight tube" is a tube with two wire cross hairs at the end. Many places sell a combination tool which does both jobs. It may look different because it has that funny 45 degree cut-out but it's a cheshire/sight-tube combo tool. Here is one such tool: Orion Telescopes: Orion Collimating Telescope Eyepiece

It's very hard to diagnose this stuff on-line but I'll try. Please answer these questions.

A) I want to get this straight: Do you have a sight-tube? Were you able to use the sight-tube to centre the primary? In other words, can you get the mirror centre spot under the cross hairs? I ask because I want to know if you're having trouble with the mechanics of the secondary alignment process.

:( You indicate that the image of the primary appears physically larger in size than the secondary itself. Is that correct? If so, is this still the case even when the focuser is racked in? If so, please take a photo through the focuser and post it here. I ask because if this really is the case then this may be the answer to your problem. Imagine trying to pass a 2p coin through a 1 cm hole: it ain't happening. Same thing with trying to see all the mirror clips if the secondary mirror is too small. It sounds like yours might be, but that is really unusual for a mass-produced scope. A photo through a racked-in focuser would help to confirm this. If it's the case then I can advise on what to do next.

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jmfdiver

jmfdiver

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Thanks Umadog Yes I have a cheshire with crosshairs, So whats a little end cap with a central hole called? (thought it was cap) Anyhow I have both and sometime today I will also have a laser collimator. What I'm saying is with the focuser fully racked in (or out) with cap or cheshire I can't get all 3 mirror clips in view at the same time. no matter which way I tilt swivel or turn or back and forth the secondary mirror. Could it be something to do with primary?

Going to keep trying before I turn this scope into a piece of "art".

Thanks for reply I will get some pics posted in a bit jen

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RikM

RikM

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This being able to see all three clips is not the 'be all and end all' of collimation. With my 150P I can't see the whole of all three clips because of the small size of the secondary. I can just see the front edge of all the clips so I adjust until these thin black slithers are equal and then get on with the next stage. I use a Cheshire combo tool (which is generally just called a Cheshire these days, a cap with a hole in being referred to as a 'Colli cap').

Lasers may seem easy to use "coz you jus line up the dots innit?" but I find I can get more accurate collimation with a Cheshire.

Don't get too hung up on these morror clips. Just get them equally spaced around the edge and you will be fine.

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TheThing

TheThing

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The A_B guide over complicates a simple subject. Far too much fussing about.

I've said it before and I'll repeat it. Ignore A_B's guide. It causes more problems then it cures. 99% of the posts here about collimation problems start with '...I've been following A_B's guide and I'm having problems...'

You are far better off following the Andy's Shot Glass videos.

Unless, of course, your prefer stress and an out if collimating scope! :(

TheThing

Sent from my iPhone using Tapatalk

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