Hello Glenn
Those are very useful information's
I was prepared as you suggested at the daylight.
And also I had a short experience at a night.
Any way the session is over now and I am looking the negatives and the
films prints.
The first impressive thing I have to notice regarding the GEG , is that
there is no any
vigneting (just a small piece at the very edge of the plane corners) and
also the
stars are very acceptable at the edges.
The negative is that in F6.3 mode the GEG requires a very long of axis tube
to came in focus the of axis star and this has some limitations regards
to the tube position related with the telescope forks.
The 216XT at least it made it (yes the thing is worked for 45min successful
auto guiding).
but I noticed that in F10 the guiding star is quite spread so the 216
exposure times
is longer than 10 sec even at bright stars. I thing if the guiding was at
F6.3 the
guiding star might be more pin point making easier the guiding.
I wonder if there is a reducer for the 1 1/4 ".
Overall I am satisfied from the equipments and soon I will advertise the
results on my
web.
A real thanks to you Glenn and I wish you clear skies.
George Nikolidakis
http://www.geocities.com/ginik_gr

-----Original Message-----
Sent: Saturday, February 17, 2001 11:46 PM
Subject: [M]: Re: 216XT parameters for Autoguiding 12" LX200

If its not too late, I would recommend putting it all together
(SCT/GEG/Camera/CCD) and preparing during the daylight.

Bring the film camera to focus on something distant. Using en eyepiece,
adjust the position of the GEG guider tube so that it is positioned such
that a part of the object the film camera is focused on is in its field of
view of the eyepiece. Put the CCD camera in the off guide tube of the GEG
and hook it up to a computer so you can view its images. Pull the CCD camera
in and out until you reach a reasonably good focus. You need to take note of
this position so you can set it up in the dark. If there is enough room you
can use the slip-ring to mark this position, if not you can make a gauge or
measure with a caliper. Getting things working the first time in the dark is
tricky. Much easier if you experiment in the daylight.

At this point I can get set up pretty quickly in the dark. Once the scope is
polar aligned I slew to the object, check that its in the field of the film
camera. With an eyepiece I search for a guide star by rotating the GEG guide
tube and center it. Note the RA and Dec directions in the eyepiece. Slide in
the CCD camera to its focus position and oriented so that up/down/right/left
match the RA/Dec you observed in the eyepiece. At this point, the CCD should
be reporting brightness and position of the guide star on the chip. Due to
the difference in weight between the CCD and eyepeice and/or the CCD chip
being located slightly off-center, the guide star might need to be centered
with respect to the camera. You also might need to adjust the exposure but
I've used it from anywhere between a brightness of 10 to 85. Now just
calibrate and begin the exposure.

I used to guide visually and know how critical it is to do a good job.
Because of this I try to make it as easy as possible for the CCD camera by
picking nice bright guide stars and orienting it to RA/Dec. The 216 may not
need that much "baby-ing" but I've never had bad guiding due to the guider.
Wind, focus shift, and passing clouds but not the guider.

-Glenn

----- Original Message -----
Sent: Saturday, February 17, 2001 6:02 AM
Subject: [M]: RE: Re: Re: 216XT parameters for Autoguiding 12" LX200


> Hello Glenn
> I want to thanks you for the useful information's
> After that it is more clear the settings for the 216XT.
> The GEG guides at the F/10 while shoot in F/6,5 so I will have to
> cut in half in both modes F10 and F6,5.
> I will give a try this evening.
> Thanks
> George Nikolidakis
>
>
>
> -----Original Message-----
> Sent: Saturday, February 17, 2001 5:55 AM
> Subject: [M]: Re: Re: 216XT parameters for Autoguiding 12" LX200
>
> After reading this when it arrived back via the mail list I realized it
> wasn't clear. I changed the Cr and Cd to match the F/10 3000mm focal
length
> I was shooting at (I think I cut them in half). If I was shooting at F/6.7
> 2000mm I would leave them at the factory defaults.
>
> -Glenn
>

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