Re: [APML] choosing a guidescope

[Alan Voetsch <alanv12952@yahoo.com>]

Hey Craig,

--- Craig McIntyre <craigmcintyre@optushome.com.au> wrote:
> 1. Assuming that the guiding is spot on, am I still going to suffer
> trailed images due to mirror flop on the C8? 

Most likely.

>  Can this be eliminated by making sure the mount doesn't cross the 
meridian during an  exposure?

Nope. There are way too many different SCT mirror movements to bother
trying to compensate for them. It can be done, but you will most likely
end up looney-tunes first.

I'd strongly suggest that you start with a quality OAG/flip mirror
combo such as the Taurus Tracker III, or the Lumicon GEG, or EG. I use
the Taurus and it makes things much simpler in the long run. Matter of
fact, I have now ditched the Losmandy DSBS, DMM, DUP, rings AND
guidescope, and am guiding my Tak FS-102 refractor off axis with
another Taurus.

Any SCT user is going to be better off guiding off axis. The mirror
rotates, flops, shifts, settles and contracts. No guidescope can get
you through that. Maybe, if exposures were kept under an hour or so.
But generally with an SCT you will be pushing 2-4 hours on exposures
(at least I do). Shooting M16, M27, M57, M8, M20 and the like, you can
keep exposure times down, but once you get past those, exposure times
need to rise. There are tricks you can use to keep mirror movement to a
minimum, but it IS going to move. 

Alan



	
		
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