leo82 Posted September 3 Share Posted September 3 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. Link to comment Share on other sites More sharing options...
Pixies Posted September 3 Share Posted September 3 (edited) 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 1 Link to comment Share on other sites More sharing options...
woldsman Posted September 3 Share Posted September 3 You can add an extension or pull the eyepiece out slightly if outward travel is the problem - or pick a target further away. Link to comment Share on other sites More sharing options...
Kon Posted September 3 Share Posted September 3 You need to do a star test to verify collimation, looking at a terrestrial object will not give you an answer on collimation. Link to comment Share on other sites More sharing options...
leo82 Posted September 3 Author Share Posted September 3 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. Link to comment Share on other sites More sharing options...
Louis D Posted September 4 Share Posted September 4 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. Link to comment Share on other sites More sharing options...
Mr Spock Posted September 4 Share Posted September 4 Before you get to the star test, the easiest way to collimate a Newtonian is with a laser. Here's something I did earlier... Link to comment Share on other sites More sharing options...
Mr Spock Posted September 4 Share Posted September 4 I have no idea why when you link to a thread it displays some random post in the thread instead of the original post... 1 Link to comment Share on other sites More sharing options...
Gfamily Posted September 4 Share Posted September 4 (edited) 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 Link to comment Share on other sites More sharing options...
bosun21 Posted September 4 Share Posted September 4 Yes I wondered why I received a notification for this. Link to comment Share on other sites More sharing options...
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