The old rule for visual guiding used to be the longer the better, but since the advent of CCD cameras for guiding you can get away with very short focal length guidescopes. With a 1000mm fl imaging scope you could theoretically use a 200mm camera lens. All of those scopes would be perfect for the job with the 100X600 f6 probably being the pick. Aperture rules
What about a Long Perng 80 x 480mm achro refractor from Andrews? Same basic mechanics as the William Optics ZenithStars for AU$399.
From the Andrews website:
Quote:
Ruby red tube colour, achromatic 80mm x 480mm f/6 OTA refractor with smooth 10:1 dual speed Crayford style focuser, of superb overall mechanical quality, in custom-cut foam liner and carry case.
Don't forget that you'll most probably need guiding rings.
im pretty much in the same boat as you guys are, i was originally going to get an ed80 as a guidescope/alternative imaging scope but the focal length is very similar to my newt.
though after seeing the prices of the achro refractors im still leaning towards the ed80, its a tough call really but i don't want to pay $300 for a scope that would give inferior images in comparison even if im not going to be looking through it on a regular basis.
There are other factors for guiding. I used an ED80 and then an ST80. I found the later was superior for many reasons, although it was not suitable for imaging. The ST80 is widerfield, never short of a guide star, and its is also much lighter than an ED80. This means more stable guiding on a marginal mount (less loading) and less differential flexure, which for me was the critical difference. With the guide cam bolted hard to the ST80 and scope with no rings and no ability to refocus (not essential, once set) I can get 15-20 min subs without obvious flexure (I couldnt get this with the ED80).
With CCD soft and Maxum DL, I found guiding accuracy is fine, even tho the ST80 has a shorter FL than the ED80, with a long FL imaging OTA (>2m).
Of course the ED80 is 1st choice if you wish to image with it too, but purely for long exposure guiding performance with an average mount, the ST80 is better (and cheaper).
I recently picked up a Stellarvue F60M finder to use as a guidescope. Its very light (only 680g with tuberings) and takes a 1.25 inch eyepiece so the DSI fits snugly. I use it with a 2x barlow.
Total cost (delivered to Sydney) with tube rings was $305. Have a chat to Peter Read at SDM - peteread@mcmedia.com.au
Be careful of other bit and pieces required I just bought a Zenith Star 80mm guidscope to fit on my Meade SCT, then had to get a Rail and Rings, a counter balance set, and further 3d counter balance set, and I havnt even tried it yet, as Im to knackered working to pay for it all
Best of luck
Be careful of other bit and pieces required I just bought a Zenith Star 80mm guidscope to fit on my Meade SCT, then had to get a Rail and Rings, a counter balance set, and further 3d counter balance set, and I havnt even tried it yet, as Im to knackered working to pay for it all
Best of luck
Jeez BOBBY,
Can't you just use superglue like the rest of us!!!
Doug
Last edited by dugnsuz; 06-09-2007 at 08:21 PM.
Reason: one to many f's
hi david, i have to admit, with my NGT10" F4.7 newt. and the ED80 guidescope along with camera and other accessories attached, the EQ6 just handles it. I don't agree getting the ED80 as a guidescope unless you also use it as an imaging scope.
David, bewarned, Eric has it in one, he has experience with the EQ6. despite the capacity of your mount, go light, as differential flexure is also a problem. Optical quality dont matter for guiding , so also save some bucks.
We have been fortunate to find an IIS member who has updated his guide cope recently and we are able to purchase his Skywatcher/Saxon 70x500 guidescope with a tube weight of 1.05 kgs plus rail and rings so this will do us nicely.
Guidescope - Which One ??
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