Re: [APML] flared stars in one corner

["Bobby Middleton" <bobm@koyote.com>]

Thanks for all the suggestions. My scope is f/7 which is not so bad
for nailing collimation as a fast scope. I've noticed something else in the
flaring. A close look at the trailing shows that the stars trailed then
appeared to
stop. Since there is no trailing over the whole neg I would think that this
is film creep.

Bobby Middleton



> Whats the Focal ratio of you scope?
> it look to me as if not collimate Laser collimator's are not the end all.
> they get you close the last word in collimation, is to star collimate. I
> like use the laser first, then star collimate every befor a night of
> imaging. ( which here in the NW was last summer)eeeeeeer. any way, I have
a
> very fast Newt and star collimating is the only thing that has worker me.
I
> would'nt rule out flexure ether.
> ttfn
> ken
>
> ----- Original Message -----
> From: Bobby Middleton <bobm@koyote.com>
> To: <astro-photo@seds.org>
> Sent: Monday, January 10, 2000 10:17 AM
> Subject: [APML] flared stars in one corner
>
>
> > I've had a few problems with my  12.5" newt on a few pics. I've had
> > some random trailing across the entire field on a few shots. This occurs
> > more often
> > when I shoot far southern targets like the helix nebula. This would be
> > either
> > an out-of-tune mount or some flexure between the camera and guide tube.
> >
> > I have another problem I've seen on a few shots. I've posted 2 cropped
> > portions
> > from one shot.
> >
> > http://www.koyote.com/users/bobm/12problem.htm
> >
> > Funny thing is I did a pair of this target and the other neg looks
> > exactly the same. You will see one crop (the top) from one corner is
> pretty
> > much OK
> > except for what I assume is the normal minor coma from an f/7 system.
The
> > length
> > of this crop is about 1/4 the length of the neg. The bottom crop shows
> much
> > more severe
> > flaring of stars from the opposite corner of the neg; they are flared
into
> > 1/3rd of the
> > entire neg. The bottom crop is the same scale as the top.
> >
> > I did a N2 purge on this although I am introducing from the back of the
> > film.
> > So I'm not sure this is adequate. Is it film creep or something else?
> > Bobby Middleton
> >
> >
> > --  APML Archives at <http://www.system.missouri.edu/apml/>  ---
> >                 Unsubscribe at <majordomo@seds.org>
> >
>
>
> --  APML Archives at <http://www.system.missouri.edu/apml/>  ---
>                 Unsubscribe at <majordomo@seds.org>


--  APML Archives at <http://www.system.missouri.edu/apml/>  ---
                Unsubscribe at <majordomo@seds.org>