I am looking to buy a guide scope for my LX200 12''. I am looking for a decent scope for a lower price. Any suggestions?

Thanks,

Gerry

Howdy.
You might want to consider an 80mm ED type, which can double as an imaging scope for a wider field. Orion, Skywatcher, etc., alledgedly all come out of pretty much the same factory in China these days. I use an 80mm Orion ST, which I got 2nd hand. Try Astromart, I think it is or Google for Astronomy classifieds.
Hope that helps.

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Lots of other Astro bits

I'm looking for the same thing for my 10" LX200.  I image at either F10 or F6.3.. apparently the F speed of the guidescope should be slower than that of the telescope.  Any advise as to what the focal ratio should be?  Is a slower focal ratio a higher number, or lower?

Shawn

 

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10" LX200 Classic"
DSI 2 Pro, DSI C, ToUcam PRO II
Toronto, Canada

Hi, Shawn

You want the speed (F-ratio) as fast as you can get it so as to pick up fainter guide stars.

As for focal length, the "old" rule of thumb was to shoot for 2x the FL of the imaging scope. Nowadays modern guiding applications use "sub-pixel" guiding algorithms, and we find that 1/2 the FL of the imaging scope is usually more than adequate (assumes you have properly tuned the mount). Guys running the high-end mounts (like, Paramount, AP, TAK, etc.) report success with FL's 1/5 that of the main OTA, but I would not recommend that with the LX200 mount.

Popular choices include the Orion ED-80 and the AstroTech AT80 series scopes. A number of folks are using the 66mm class with good results too. I have a 10" LX200R, and got great results with the ED-80 for a long time. (I recently upgraded to a TMB-80)

I would just add that selecting a guidescope with good optics & a decent focuser will greatly expand your imaging opportunities...many of us find ourselves imaging through the small refractor as much if not more than we image through the LX200!

Chuck

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Chuck Reese
CDIP Certified: Nebula, Galaxy, Solar System, Stars & Clusters Imager
CDIP Mentor: Nebulae & Solar System Categories
For information on the Certified DSI Imager Program, see:
http://autostarsuite.net/forums/1427/ShowForum.aspx

Thanks Chuck, exactly what I needed to know.  I bought a little ETX-60 some time ago, gutted it and mounted it on top of my LX, but the focuser has proven to be the greatest challenge.

What I'm finding a little confusing is whether I NEED an "ED" scope, or whether any refractor with suitable focal length would do.  There are a lot of little scopes out there that are very reasonably priced (iOptron SmartStar E 80mm, Antares 80mm Sentinel Refractor, Sky-Watcher 80mm Equinox, Sky-Watcher 80mm tabletop refractor, etc).  Although I know that generally more $$ is better quality, I want as much quality for the little $$ I have to spend!  lol

Shawn

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10" LX200 Classic"
DSI 2 Pro, DSI C, ToUcam PRO II
Toronto, Canada

Yeah..."need" is such an interesting word

You do not "need" an ED for autoguiding. You do need a robust enough focuser to support the weight of the guide camera without flexing as the scope tracks your target across the sky. Other than that, pretty much any achro will work fine. You can then utilize a -V / Fringekiller type filter to try some widefield imaging with it. By buying an achro of the same size as your planned possible future ED, then the rings, etc. will all work when & if you decide to trade up.

Chuck

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Chuck Reese
CDIP Certified: Nebula, Galaxy, Solar System, Stars & Clusters Imager
CDIP Mentor: Nebulae & Solar System Categories
For information on the Certified DSI Imager Program, see:
http://autostarsuite.net/forums/1427/ShowForum.aspx