[ATM] Ultimate Collimation

[johncdeitz@comcast.net]

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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