Colimation trouble

[leo82]

So I thought it'd be a good idea to colimate my 200p dob. My little one had tried playing with the secondary mirror, hence my need to colimate. I tried following the astro baby tutorial. I thought I'd been successful until I tested out on a chimney I can see which is a couple of streets away. With my 25mm eyepiece in place I can't seem to bring the chimney into focus.  The problem is I run out of outward travel just as it starts to come out of a blur and into focus. Where have I gone wrong? 

Thanks. 

[Pixies]

The chimney is too close, if you are running out of focus. In my dob, I need to use a very distant object to get focus.

Edited September 3 by Pixies

[woldsman]

You can add an extension or pull the eyepiece out slightly if outward travel is the problem - or pick a target further away. 

[Kon]

You need to do a star test to verify collimation, looking at a terrestrial object will not give you an answer on collimation.

[leo82]

Thanks for your replies. I've checked with the eyepiece extended eyepiece and got a clear view. I understand I have to do a star test but for now I just wanted to see if I could get any kind of view, no doubt I'm still going to be out of colimation when I do test it out in the dark. 

[Louis D]

You can try using a reflective Christmas globe ornament or ball bearing with a flashlight (torch) shining on it from a distance to create an artificial star.  You do need to be in a darkened environment for this to work.  If indoors, you could try using mirrors to double the distance.  That, and you'll probably need an extension tube to reach focus.

[Mr Spock]

Before you get to the star test, the easiest way to collimate a Newtonian is with a laser.

Here's something I did earlier...

 

[Mr Spock]

I have no idea why when you link to a thread it displays some random post in the thread instead of the original post... 

[Gfamily]

23 minutes ago, Mr Spock said:

I have no idea why when you link to a thread it displays some random post in the thread instead of the original post... 

The link you posted included the <#comment-4443538> which took us to the in-thread reply rather than the top of the thread.  I don't know why it did that either. 

Edited September 4 by Gfamily

[bosun21]

Yes I wondered why I received a notification for this.