Re: [APML] Sky-watcher

["Joseph O'Neil" <joneil@multiboard.com>]

Hi;

At 21:22 02/05/02 +0200, you wrote:
>Does anyone of you have experience with Sky-watcher refractors?

         Yep, I sell them.

>I am thinking of purchasing a 102/500 rich-field refractor on an EQ-3
>mount or a 120/600 rich-field refractor on a Gem-1 mount.

         The 102 has a lot of chromatic abberation, and some other faults 
too.  Not wishing to bite the hand that feeds me, but I cannot reccomend it 
as a serious astro-photo instrument.  If you want to do some black7white 
work using a yellow or Minus Violoet Filter from Sirius optics, that might 
work,b ut the scope is really a visual instrument.  Not saying you cannot 
try it, but I think ultimately, you'll be fustraited.

         As for the EQ3 (or EQ5) mounts, they are not, IMO, suited for 
astro-photo use, even piggyback, as they are.  To explain in detail, look 
up these two web site:
1)   http://www.astronomyboy.com
         specifically "Regreasing the CG5 mount"
and
2) http://overton.tamu.edu/rdb/CG5/wormgear.htm

         This second link explains weaknesses in the worm gear drive.
         Although specifially talking about the CG5 mount, both web pages 
are just as viable for the EQ3 mount.

         Rebuilding your mount as described on these web pages will giv 
eyou a mount suitable for wide angle, piggy back work, but not, IMO, 
suitable for any prime focus work.  Also, tearing apart and rebuildign the 
mount will, void any and all warranties.  Bummer, eh?


>I want to get started with astro-photography and my original intention
>was to buy a Meade ETX but this has been discouraged as unsuitable
>for astro-photography.

         At around F13 or F14, that is one slow lens.


>Look forward to your thoughts and comments on this.


         Buy a used Vixen GP mount, and do piggy back work to start.  The 
true GP mount by Vixen is actually quite a nice mount for piggy back work.
good luck
joe



http://www.oneilphoto.on.ca
http://www.multiboard.com/~joneil
"Una salus victus nullam sperare salutem"


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