Alternatively, I believe you can buy a Chesire eyepiece for about $35
or thereabouts which should do the trick for this application.

M.

> -----Original Message-----
> Sent: Thursday, April 02, 1998 1:45 PM
> Subject: Re: [M]: Collimating a Refractor
>
> This looks like some good sugestions, can a laser presentation pointer
> be used
> as the laser source? How about the laser colimator that is listed in
> Orion
> catalog for $35, it says it is for Newtonians, but if it works as a
> laser point
> light source, then maybe it can be used for your procedure?
>
> BTW, I already knew about the push/pull adjustment system. And your
> comments
> about making sure not to pinch the cell by overtightnening the
> adjustments is
> very well taken along with trueing up the focuser centerline!
>
> Thanks
> m.
>
> Tom Clark wrote:
>
> > Collimating a refractor without some real method of aligning the
> optical
> > path can cause a severe case of frustration. I have a 5" Meade EDapo
> also,
> > and was really not very happy with the focuser mechanism. There is
> no way,
> > short of trying to tighten the tube mounting screws, to adjust the
> angle of
> > the focuser tube. I know this may sound like a lot of work, but here
> is what
> > I did to achieve the ability to separate 1" double stars, and see
> very near
> > perfect diffraction rings.
> > I first used a laser collimator in the scope using a piece of
> paper over
> > the end of the tube with a center dot on it to verify that I had a
> problem.
> > The spot at the objective was about 1/4 inch from being centered.
> Obviously
> > I had a focuser problem. I removed the focuser from the tube and
> removed the
> > poly- ethylene slides that align the focuser tube in the housing.
> This
> > leaves a small amount of clearance inside the tube. I removed the
> same poly
> > slide from the aluminum bar that doubles as the focuser lock. these
> were
> > replaced with six screws with poly-ethylene tips to ride against the
> tube.
> > This makes the focuser tube adjustable like a finder scope. The
> laser
> > collimator was then reinserted and the focuser tube adjusted until
> the dot
> > was Exactly centered on the objective. The reflection can then be
> observed
> > through the objective end. It should reflect back on the laser
> collimator
> > centered. Be sure not to allow the laser to shine in your eye. I put
> 2
> > pieces of electrical tape across the center of the tube ( not the
> lens of
> > course ) for the laser to shine on instead of my eye. There are
> actually 3
> > reflections that return to the back of the tube. The objective can
> now be
> > adjusted so that the reflections are as centered as possible on the
> > collimator. Be careful not to over tighten the objective adjusting
> screws.
> > If you don't want to work on your focuser as I did, then just shim
> the laser
> > collimator until the dot is centered. My objective was out of
> adjustment
> > such that the reflections did not hit the collimator at all, so this
> method
> > helped me quite a bit. Tom
[snip]

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