Guidescope - Which One ??

[Tamtarn]

We need some help in deciding on a guidescope.

We're using a Skywatcher 200 x 1000 Newt on an EQ6 Pro Synscan and will be using a Meade DSI Pro as a guide camera.

We don't want to get an ED 80 as we will be using the scope for guiding only NO IMAGING.

Our budget is $300-$350

Our question is what focal length and aperture will we need to use a DSI Pro

The options we have found within the price range so far are :-

1. Saxon/Skywatcher 70 x 500 f7 Refractor
(A member of IIS has used this as a guidescope and is very happy with it)

2. AOE 80 x 600 f7.5 Refractor OTA

3. Orion 80 x 400 f5 Short Tube Refractor OTA

4. Orion 100 x 600 f6 Refractor OTA

Any suggestions, advice or input on the scopes we have listed or any others you have used would be appreciated to help us make a choice.

Thanks in advance

D & B

[[1ponders]]

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 ;)

[Omaroo]

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:
Don't forget that you'll most probably need guiding rings.

Cheers
Chris

[Tamtarn]

Thanks Paul and Chris.

Chris the Long Perng looks great but including the guiding rings it bumps it up a bit in price for what we want to pay.

We will wait for any other suggestions at this stage

[monoxide]

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.

[Bassnut]

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).

[dugnsuz]

I don't know if a 66mm scope would cut it, but Telescopes and Astronomy have the 66mm Petzval Semi Apo for $330 - could maybe image with it too!!??
http://www.telescopes-astronomy.com.au/william_optics_telescopes_zenithsta r_megrez.htm

Cheers
Doug

[pvelez]

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


It works a treat for me


Pete

[BOBBY]

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:P

[dugnsuz]

Jeez BOBBY,
Can't you just use superglue like the rest of us!!!:lol:
Doug:thumbsup:

[Tamtarn]

Thanks for the ongoing advice guys.

Weight should not be a problem, as the EQ6 has a carrying capacity of 25 kgs and our ota weighes 8.75 kgs

David

[EzyStyles]

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.

[Bassnut]

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.

[dugnsuz]

There's a 70mm OTA on the Andrews Surplus page for $149
Doug

[Tamtarn]

Thanks Eric & Fred

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. :thumbsup:

David