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Re: [OM] OT astrophotography - was Zuiko telephoto fro astrophotography

Subject: Re: [OM] OT astrophotography - was Zuiko telephoto fro astrophotography
From: "Carlos J. Santisteban Salinas" <cjss@xxxxxxxxxxxxx>
Date: Sat, 10 Aug 2002 11:29:39 +0200
>Maybe with a
>perfectly aligned mount and RA drive (I don't have one) I might 'almost' not
>have to adjust DEC or RA axis for several minutes.

Yes, that's what I mean. Maybe I'm not using the right words, but I
understand that 'tracking' is the way to compensate for earth's motion
(from a barn-door to an equatorial mount), and 'guiding' is the task of
making (tiny) adjustments during exposure to achive perfect tracking.

A longer lens will be much sensitive to tracking errors, of course, but
there are also other risks. If the lens is slower, exposure time will be
longer, and might show the least alignment inaccuracy -- that's why I don't
recommend a teleconverter.

Also, a heavier (and/or worse balanced) lens will make the work of tracking
motor more difficult, due to uneven friction, gearing eccentricities, etc.
So guiding with the eye glued to the eyepiece is a must, both correcting on
the RA axis (drive speed) and declination axis.

>(my scanner does an awful job on dark slides)

So does mine ;-)

...

Carlos Santisteban

<cjss@xxxxxxxxxxxxx>
<cjsantis@xxxxxxxx>



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