Crosshairs

[Kaznkev]

I took my telescope out for the first time in about 3 weeks and I can see a dark circle in the middle with 4 lines coming towards it. Like crosshairs.

Does this mean my scope needs to be adjusted?

I read a bit about collimation, is that what I need to do?

From what I read I need to buy a Cheshire collimating EP.

Do I need one or is there another way to do it?

[Stu]

Sounds like it is just out of focus?

[John]

I agree with Stu - this is a focus issue.

The dark circle and the black crossed lines are the shadows of the secondary mirror and it's supports and seeing them means that the scope is not focussed properly. It's not the collimation so no need to worry about that yet.

As you get closer to sharp focus those shadows will dissappear.

[Kaznkev]

I noticed that it was the focus after I started this thread. I feel like a complete idiot.

The other mistake I made was not allowing the telescope to cool.

Just goes to show how much of a beginner I really am. I suppose I'll learn from my mistakes.

On a side note, how often will my telescope need collimation? I know it doesn't need it right now but should I be thinking about getting a Cheshire collimating EP so that I have it ready when I do need it?

[PeterCPC]

What type of telescope is it?

Peter

[Stu]

I noticed that it was the focus after I started this thread. I feel like a complete idiot.

The other mistake I made was not allowing the telescope to cool.

Just goes to show how much of a beginner I really am. I suppose I'll learn from my mistakes.

On a side note, how often will my telescope need collimation? I know it doesn't need it right now but should I be thinking about getting a Cheshire collimating EP so that I have it ready when I do need it?

Please don't feel silly, we all need to learn, and I bet most of us have done something similar at some point. Whether we admit it or not is a different matter [emoji6]

I'm assuming your scope is a newtonian? A Cheshire eyepiece will be very useful for collimating the scope when needed, and there is plenty of advice on the forum and the web when you need it.

This is a very good place to start;

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

EDIT Frequency of collimation will depend a lot in the scope and how much it is moved. It's worth checking every time though. The secondary doesn't need doing often, but the primary will probably need a tweak fairly regularly. Once you know how it's very straightforward.

Stu

[PeterCPC]

It sounds like a Newtonian but Iv'e learnt never to assume anything!

Peter

[John]

I noticed that it was the focus after I started this thread. I feel like a complete idiot.

The other mistake I made was not allowing the telescope to cool.

Just goes to show how much of a beginner I really am. I suppose I'll learn from my mistakes.

On a side note, how often will my telescope need collimation? I know it doesn't need it right now but should I be thinking about getting a Cheshire collimating EP so that I have it ready when I do need it?

Don't worry about it - when I think of some of the things I did when I was learning the ropes

Glad it's sorted now

[Kaznkev]

Thanks for making me feel a little less like an idiot.

My telescope is a skywatcher explorer 130p.

[PeterCPC]

As this is a solid tube rather than flex tube type ( Flex tube Dob), it should hold collimation reasonably well unless it is subjects to bumps in travel etc. For visual use the collimation accuracy is not so crucial as with imaging but still needs to checked from time to time. There are threads about collimation of a Newtonian and stuff on the web such as this http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

I hope that helps.

Peter