Re: [ATM] Ultimate Collimation

[marinus van der Lugt <lugt@xs4all.nl>]

Hi John,

 > 1) remove reflective coating in center of mirror, about 1/8 inch

You have to be quite sure about the center though.
Is there a good way to find it?

Rien.


On Sep 2, 2007, at 15:26, johncdeitz@comcast.net wrote:

> Hello Gang: Try this for the ultimate in Newtonian Collimation-
> 1) remove reflective coating in center of mirror, about 1/8 inch
> 2) if mirror cell is solid provide hole through cell at center
> 3) shine a light at the hole from behind the cell (I use an LED  
> with variable brightness so as to preserve vision- this fits in  
> snug hole at center of the back of mirror)
> 4) using an autocollimator eyepiece, with the optics roughly  
> aligned, you will typically find two spots of light from the LED  
> (or flashlight etc.). Tweak the mirror to bring these two into one  
> and you will see an additional reflection that is quick to change  
> position- this is very sensitive method! Bring all three head-on  
> and your view is flooded with light as with conventional  
> autocollimator. You will find enough play in the autocollimator  
> that his spot will wink on and off as you play with the  
> autocollimator in the focuser.
> This method offers the following advantages:
> 1) you can follow the whole action continuously as the cell is  
> tweaked, unlike with the conventional use of autocollimator
> 2) can be performed in suboptimal seeing with accurate results
> 3) no problem with off-set.
> 4) can be performed without ruing night vision so you will not  
> hesitate to repeat.
> 5) can even be done by one person!
> John C. Deitz
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