Hi Ray -- Gene's suggestions below are excellent. However I use
another method which works well for me.

With the CCD camera in place, I center a single medium bright star
in the FOV on my computer. BTW, I have a red magic marker ink
"dot" on my monitor screen in exactly the center of the FOV.

Then I defocus the star --enlarging the rings till they virtually fill the
fov. Now you can easily see the amount of "de-collimation" that you
have. I then start to "tweak" the collimation screws. After each
"tweak" I recenter the star. I repeat till all is centered at the center
mark on my monitor.

I have a permanant pier mount. I collimate at the most twice a year.

Best regards

Frank

> Ok to everyone that has helped on this. I see a light at the end of the
> tunnel here. I can from most comments adjust the collimating using the
> star method. This all makes sense to some degree. I am not going to rush
> right out and spend money on a collimator. I will give it a chance to see,
> what I see, when viewing. I may still want to invest in the collimating
> device at a later date just to make extra sure I have it set the best. I
> am looking at long duration astrophotography. And with a viewing site at
> 8000 ft level I should have some fairly good seeing nights. I have a cliff
> overlook at that level. Thanks again for all the help to everyone.
>
> dray
>
> Gene Horr wrote:
>
> > "D.Ray East" wrote:
> >
> > > I asked one of the local group here about collimation on the 12 inch
> > > Meade LX200 scope. He said the is very little you can do to them and
> > > they always come out right from the factory. I am wondering is this
> > > true?
> >
> > No. Merely slewing from one side of the sky to the other will ruin
> > perfect collimation (see Legeault (sp?) for a very good discussion on
> > this).
> >
> > Now, to confuse things further, this may not matter too much for a
> > beginner. Critical
> > collimation becomes important for high power planetary work or when you
> > are trying to get that last few percentage points of resolution. For
> > typical medium/low power DSO viewing the collimation can be waaaaaay off
> > for the typical user before it even becomes noticeable.
> >
> > But IMO it is still a good idea to get in the practice of checking
> > collimation after the initial cool down. Once you've done it a few
> > times it becomes a simple and quick procedure. This is another good
> > project to practice in the back yard so that you don't waste dark sky
> > time learning mechanics.
> >
> > A few tips:
> >
> > Don't use too bright of a star.
> > Use the highest power the seeing will allow (at least 250X.
> > Preferably closer to 500X)
> > Defocus just enough to see the diffraction rings.
> > Center the diffraction rings, NOT the "donut hole".
> > Keep the cell on the pivot point by loosening two and tightening
> > one.
> > Tighten the screws down when done.
> >
> > BTW - a LOT of the negative comments you hear about mass-market SCTs
> > come from people not allowing them to cool down and not properly
> > collimating them. Of units produced over the past 5 years or so I have
> > only seen one truly bad set of optics and only a handful of poor ones.
> >
> > Gene Horr
>
>


Best Regards,
Frank Loch
Try Deep Space 99 at:
http://home.early.com/~floch/index.html
TPoint & DEC Bearing Mod at:
http://home.early.com/~floch/observatory.htm
Hubble's Variable Nebula project page:
http://home.early.com/~floch/lnai20.htm

View index by [date] [author] [subject]
Previous message: RE: [M]: 12 inch collimation, Steve Glazener
Next message: Re: [M]: MAPUG list maintenance, R. A. Greiner
Next message in thread: Re: [M]: 12 inch collimation, D.Ray East
Previous message in thread: RE: [M]: 12 inch collimation, Steve Glazener