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I am refering to the elements in the guidescope
shifting, not the camera lenses themselves. If the elements in the guidescope
shift, then the autoguider will be foolind into thinking it must make
corrections, when none are required, creating unnecessary errors.
Some of the mirror-lens systems were made with very
sloppy tolerances, but perhaps a bit of glue here and there may solve the
problem....
Derek
----- Original Message -----
Sent: Wednesday, September 03, 2003 12:20
AM
Subject: Re: [APML] 500mm mirror lens as
a guidescope?
I have a friend who may respond separately who uses camera
lense and stv to guide quite often. His results are
great.
Mike
DEREK BAKER wrote:
I have heard stories of the lens elements shifting over long exposures, both
laterally, and in terms of focus. If your shots were just 10 or 20min,
then....
Derek
----- Original Message -----
From: George Anderson <georgea@cam.org>
To: APML <astro-photo@seds.org>
Sent: Tuesday, September 02, 2003 10:57 PM
Subject: [APML] 500mm mirror lens as a guidescope?
While messing around with getting my B&W quickcam autoguider working and
starting to worry about focuser flexure on my el-cheepo guidescope I
started wondering (dangerous habit)...
For widefield shots with a 35mm camera (50mm lens or less) would a
guidescope with a 500mm focal length be sufficient?
The 500mm f/8 mirror lens I have is very lightweight and has no
detectable barrel flexure. The effective aperture is only 62mm but that
is only a touch smaller than my 70mm f/10 scope that I use for manual
guiding.
Any thoughts from those in the know?
George Anderson
Montreal Canada
Clear skies and good health
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Michael Cole
UrbanImager Astrophotography website
http://home.earthlink.net/~urbanimager/index.htm
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