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Guide-scope suggestions for LX200

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#1 aposteriori

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Posted 29 October 2020 - 12:02 PM

Hello, I am slowly creeping back into the hobby after many years and am currently looking at eventually using an auto guider for AP when the moment comes. I currently have a Meade LX200, 10" aperture. It is the last version/iteration with the matte finish instead of the glossy OTA. I am looking for guide scope and guidescope set ups and suggestions for auto guiding. I recognize that off-axis guiding (OAG) is rightfully recommended and advocated by many due to the focal length of the LX 200 at 10" and other factors which make OAG better. However, for the time being I prefer to use a guide scope and would like "that" experience before moving on to OAG. I know in the past there have been suggestions of using refractors, apo, even Maks' (ETX 90 and 125). I was actually planning on using the stock finder but soon realized this may not be an option. 

 

What would be some of the guidescope suggestions for a fork mounted (with or without wedge) LX200 10"? Any guidescope and/or camera suggestions would be greatly appreciated. 

 

Thank you



#2 StarmanDan

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Posted 29 October 2020 - 03:21 PM

I use an ST80 on my 8 inch LX200. It's a bit bulky but I dont lack for guide stars with my DSI or ASI120.

#3 MikiSJ

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Posted 29 October 2020 - 03:52 PM

ZWO, QHY, Orion and others make guide scopes but you should really rethink using an OAG for guiding such a long focal length OTA, especially on a more pedestrian mount the L200 comes with and without a wedge you will be fighting rotation.



#4 aposteriori

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Posted 29 October 2020 - 05:10 PM

ZWO, QHY, Orion and others make guide scopes but you should really rethink using an OAG for guiding such a long focal length OTA, especially on a more pedestrian mount the L200 comes with and without a wedge you will be fighting rotation.

I will go into OAG in due time. Form what I’ve gathered the learning curve is steep here.



#5 jgraham

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Posted 29 October 2020 - 05:34 PM

I like the Astro-Tech 60mm guidescope; solidly built and an excellent helical focuser.



#6 MikiSJ

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Posted 29 October 2020 - 06:13 PM

I will go into OAG in due time. Form what I’ve gathered the learning curve is steep here.

Actually, you may be lengthening the learning curve with a separate guide scope significantly shorter than the 2500mm of the LX200. If you begin using the OAG then you won't be chasing possible flexure issues with the guide scope mount. Also, you will find tracking on a guide star more difficult with the differential in guide star/pixel scale versus the OTA/image scale.

 

I have found it much easier to guide with an OAG versus a separate guide telescope. I had a TAK 152 on a Paramount ME and added a TAK 78 as a guide scope with little success because of flexure problems. But when I moved to an APM/TMB 152 and a QSI532 with a built-in pickoff mirror my guiding issues were over.

 

I currently use a Celestron OAG with my C11 EdgeHD and it was very easy to setup.



#7 jgraham

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Posted 29 October 2020 - 08:51 PM

I went the other way; started with a OAG and switched over the using a guidescope. I like the wider field of the guidescope. It also works well as a remote finder.

 

My 10" LX80/Atlas fitted with an ETX-60 guidescope...

 

Atlas 10in LX80 (10-18-2019)-2.jpg

 

 



#8 jgraham

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Posted 29 October 2020 - 08:52 PM

My C11/Atlas fitted with the Astro-Tech 60mm guide scope...

 

Atlas C11 (3-11-2020)-1.jpg

 



#9 aposteriori

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Posted 29 October 2020 - 10:54 PM

Thank you all for the replies! I've been told that the focal length of the guidescope should be at least 1/4 ( a quarter) of the main scope. Given the FL of the main scope being 2500 any recommendations that would accommodate this  suggestion?

 

Thank you



#10 jgraham

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Posted 30 October 2020 - 02:39 AM

Weird. I've never heard that before. The devil is always in the details, but if you dig into the math you need to consider the true resolution of your imaging system, guiding system, and the guiding software keeping in mind that most modern guiders provide sub-pixel guiding resolution. I have used guide scopes on my 10" f/10 with focal lengths from 300mm to 1250mm with good results. I really haven't noticed much difference between them. The most important factors have been a solid mounting for the guide scope, a solid connection between the guide scope and guide camera, and making sure that the locking ring that secures the SCT's primary mirror is snug. All of these contribute to controlling good alignment of the imaging and guiding components.

Just for yucks you might search the imaging forums and see what people are using.

Food for thought.


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