RE: ATM Collimation Question

["Bertapelle, Ken" <Bertapelle.Ken@tci.com>]

Jim,

IMO, the final assessment on collimation has to be made through a real
eyepiece and looking at a star.  The laser, I agree, is a very nice tool,
but it's still not error free.  What I've been finding is that after
collimating with the tools, there is a spot somewhere in the FOV that 
enjoys perfect collimation.  But that spot is typically not the center
of the FOV.  The final adjustment, against a star, moves that spot to 
the center of the FOV.  Wouldn't you agree?

- KenB

> -----Original Message-----
> From: Jim Fly [mailto:flyj@iol-12.net]
> Sent: Tuesday, July 06, 1999 3:58 PM
> To: Bertapelle, Ken; Bradley Davy; atm@shore.net
> Subject: Re: ATM Collimation Question
> 
> 
> >The final collimation is against a centered star (polaris is 
> best, since
> >I don't yet have a tracker), which should show the secondary shadow
> centered
> >in the diffraction rings on both sides of focus.  If the shadow isn't
> >centered (it should be close after the above procedure), then it's
> direction
> >from center gives an indication as to how to make the final 
> adjustment.
> >The final adjustment is made with the primary screws
> 
> Everything was great until at the end you relied on a visual
> assessment/judgement of the shadow centered symmetry as the 
> final primary
> adjustment criteria to in effect "defeat" that wonderful 
> precision of the
> laser you used to set the primary in step 5.
> 
> Why?????
> 
> Regards,
> 
> Jim Fly
> ATM Craftsman & Engineer
> Huntsville, Al
> flyj@iol-12.net
> 
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> 
> 
>