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tommax
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LX200 GPS and auto guiding
      #5727292 - 03/12/13 01:18 AM

Hi,

Looking for opinions... I have an LX200 GPS, I am ready to start experimenting with it with a wedge. The LX200 is connected to my laptop already via the serial connection and I have an Orion Starshoot auto guider with the mini 50MM guide scope. I would however like to put something like an 80MM ED on it in hopes I can trade between the 2 scopes for guiding / imaging depending on what I am trying to image... this makes me wonder if I would be better off getting a DSI or similar camera and using that in the guide scope rather than the Orion... Is there a distinct advantage to using the guideport on an LX200 over the serial connection? I honestly admit I have no clue and from the little I know I do not see a reason why I would want to use the guide port / orion unless there is a reason.

Thanks guys... with I could buy some of you a coffee or a beer for all your help.


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Christopher EricksonModerator
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Re: LX200 GPS and auto guiding new [Re: tommax]
      #5727338 - 03/12/13 02:14 AM

Off-axis guiders (a.k.a radial guiders) will usually give better results on compound scopes with floating primary mirrors.

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tommax
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Re: LX200 GPS and auto guiding new [Re: Christopher Erickson]
      #5727369 - 03/12/13 02:42 AM

Now I am confused, isn't an off axis guider similar to a flip mirror but both spots can see at the same time?

maybe I asked the wrong question? Am I better off then with the Orion and the guide port than say a DSI in a guide scope? Would the 50mm mini guide scope be better than an 80MM mounted?


Sorry if questions are dumb, I figure if I am putting an 80MM on it anyways... I would think and could be wrong, I don't need to 50mm mini scope and then it becomes is there an advantage for the Orion guider plugged into the LX200's guide port over just the serial connection which is already made to the lx200????


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Christopher EricksonModerator
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Re: LX200 GPS and auto guiding new [Re: tommax]
      #5727385 - 03/12/13 03:01 AM

Quote:

Now I am confused, isn't an off axis guider similar to a flip mirror but both spots can see at the same time?

maybe I asked the wrong question? Am I better off then with the Orion and the guide port than say a DSI in a guide scope? Would the 50mm mini guide scope be better than an 80MM mounted?


Sorry if questions are dumb, I figure if I am putting an 80MM on it anyways... I would think and could be wrong, I don't need to 50mm mini scope and then it becomes is there an advantage for the Orion guider plugged into the LX200's guide port over just the serial connection which is already made to the lx200????




An off-axis guider/radial guider picks off a small amount of light just outside of the field of the main camera and sends it into the guide camera. That allows the guide camera to see and compensate for things like mirror-flop (unless it is too-severe), OTA flexure, mirror sag and other stuff. Things that a piggyback scope and camera wouldn't be able to detect and compensate for.


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tommax
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Reged: 02/15/13

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Re: LX200 GPS and auto guiding new [Re: Christopher Erickson]
      #5727392 - 03/12/13 03:16 AM

Thanks so much for helping me...

If I am understanding correctly I am better off getting rid of the miniscope and using an off-axis guider with the orion guider connected to the lx200's guider port regardless of which scope I was going to image from?


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Christopher EricksonModerator
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Re: LX200 GPS and auto guiding new [Re: tommax]
      #5727448 - 03/12/13 04:45 AM

Quote:

Thanks so much for helping me...

If I am understanding correctly I am better off getting rid of the miniscope and using an off-axis guider with the orion guider connected to the lx200's guider port regardless of which scope I was going to image from?




The ST-4 compatible autoguider port on the LX200 versus serial commands over RS-232 is another issue and when everything is working well, both autoguider communications options should work well enough. Personally I have had slightly better results using the ST-4 autoguider port and a compatible autoguiding camera.

As for piggyback versus off-axis, you will find people who will argue with my recommendation to go with an off-axis guider versus a piggyback guider. A piggyback configuration will likely make it easier to find suitable guide stars but an off-axis approach will give consistently better tracking results and fewer lost frames with a compound scope with moving primary mirror. Piggyback configurations are more prone to multi-axis balancing problems too.


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Mike7Mak
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Re: LX200 GPS and auto guiding new [Re: tommax]
      #5727471 - 03/12/13 05:17 AM

Off axis guiders are great (I use one), BUT they are not all that easy to set up and use, good ones are expensive (you want a good one), and the Orion SSAG is not the camera to use on one, it's not sensitive enough.

Guiding has a learning curve, especially with an LX200gps mount. The Orion mini guider is probably the simplest, easiest way to get your feet wet. If the imaging scope can be reduced to 1500mm or less it should work ok.

The next easiest way is with a piggyback refractor but the added weight can complicate things. Balance is critical for guiding. The SSAG camera will work fine there also.

Then there is periodic error correction. At the very least you will want to 'train' the PEC with the routine in the scopes software. I highly recommend the program PemPro for much better results.

I've always used the guider port on the mount with a Shoestring GPUSB relay box. The guide output of the SSAG camera serves the same purpose. I think it's better than using the serial connection but I don't remember exactly why.


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tommax
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Re: LX200 GPS and auto guiding new [Re: Mike7Mak]
      #5728171 - 03/12/13 01:22 PM

Ok... I think it is finally sinking in now...

So from what I am gathering... please bare with me...

From what I am hearing the Orion setup is not very good, well at least for an SCT...

I would probably be better off selling the Orion mini scope and guider, getting something like a Meade DSI or similar as a guide camera, a shoestring USB and a good Off-Axis guider (I only say Meade DSI because I cannot afford $1,000 or even $500 for a guide camera)...

I have been watching / saving for a bit now toward getting one of the older SBIGs with a filter wheel and guidechip built in like the St7's.

I figured (and I might be wrong) that this would be the easiest way to learn dso imaging because everything was all in 1 but want to practice in the meantime.

Thanks again,

Tom


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Mike7Mak
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Re: LX200 GPS and auto guiding new [Re: tommax]
      #5728335 - 03/12/13 02:55 PM

Quote:

I would probably be better off selling the Orion mini scope and guider, getting something like a Meade DSI or similar as a guide camera, a shoestring USB and a good Off-Axis guider (I only say Meade DSI because I cannot afford $1,000 or even $500 for a guide camera)...

I have been watching / saving for a bit now toward getting one of the older SBIGs with a filter wheel and guidechip built in like the St7's.

I figured (and I might be wrong) that this would be the easiest way to learn dso imaging because everything was all in 1 but want to practice in the meantime.




Well 'better off' is contingent on how successful you are learning from scratch with an OAG, but in the long run probably yes. That is where I ended up after using several other configurations over the years. But I attempted to use a cheap OAG several times along the way and gave up in frustration.

My point is, like just about everything else in this hobby, guiding has a learning curve and an OAG will just make it that much steeper. All I'm really saying is, you already have the mini guider, set it up and get a taste of what guiding is like before tossing money at an OAG and used DSIs. Btw, you want a mono DSIpro 1, 2, or 3 for guiding not the color versions.

For that matter, buy a DSIpro2 (it'll make a great guide camera later) and start imaging with it and guiding with the Orion SSAG mini guider. That's the most cost effective way to "practice in the meantime". Believe me, until you try to do imaging you really have no idea what's actually involved.

Along the same lines, starting from scratch with one of the SBIG self guiding ST cameras would not be my first choice. The guide chip is behind the filters which makes finding suitable guide stars that much harder, and SBIG gear is highly proprietary. Meaning you're stuck with their software and a couple other expensive options.

Edited by Mike7Mak (03/12/13 02:58 PM)


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tommax
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Re: LX200 GPS and auto guiding new [Re: Mike7Mak]
      #5728366 - 03/12/13 03:11 PM

Thanks Mike,

All sounds like good solid advise, been watching for a DSI pro and or Orion Mono, I have a DSI II color but it is unused and I am not sure I want to use it because I had one in the past and did not like it a bunch (always had a red fuzzy screen)... I also had a DSI II pro, but with the Mono's comes another problem, part of the reason I abandoned the hobby a few years back and that was the COLD! I would certainly want a mono solution I can control the filters from the warmth of my home, I don't mind running in and out a bit, but would love not to have to, been looking at the Orion USB ones as they are the only ones I can find that are not SBIG and pc controllable... which leads to the other thing I did not like about my Pro II, it was impossible to change the filters without much movement, I even tried a manual circle wheel which helped but was not ideal... the filters are the only thing I cannot control... and to be honest part of the fun of the hobby for me is in setting it all up and controlling this stuff remotely, well and I really enjoy post processing.

Anyways I will take your advise and stand pat for the moment and experiment, I do have a cheap OAG but from the sounds of it I am better off not using a cheap one at all...


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Mike7Mak
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Re: LX200 GPS and auto guiding new [Re: tommax]
      #5728390 - 03/12/13 03:25 PM

Oh ok, so you do have some imaging experience. That changes things a bit.

Check out the Xagyl filter wheel...

http://www.xagyl.com/store_us/product.php?productid=13&cat=6&page=1

...it's inexpensive, low profile, and works great. I have it.

This is the OAG I'm using...

http://www.optcorp.com/product.aspx?pid=17675&kw=teleskop service&st=2

...if you can deal with the 35mm backfocus it's pretty nice. Solid, fully adjustable, and a large prism.

DSIs are kinda a pain due to the lack of cooling. One of the lower end Atiks would probably be a better choice for an 'inexpensive' camera.


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tommax
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Re: LX200 GPS and auto guiding new [Re: Mike7Mak]
      #5728586 - 03/12/13 05:00 PM

wow, a filter wheel for $250... looks nice I will have to check that out as soon as I get a mono camera... Thanks

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*skyguy*
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Re: LX200 GPS and auto guiding new [Re: tommax]
      #5728650 - 03/12/13 05:29 PM

I've used an 80mm f/4 guidescope ... with an Orion SSAG connected directly to the guide port ... on my 12" LX200 @f/6.3 for years with great results. Before that, I suffered for a long time using an OAG ... I could never get my scope to guide properly, even when I could find a suitable guide star. After switching to a guidescope ... dare I say it ... guiding actually became, FUN!

That said, the 50mm guidescope might be a little too small if you plan on imaging at a focal length much over 1500mm. Other then that, you'll probably find autoguiding easier to learn and do using a guidescope instead of an OAG. However, you will find astrophotograhers who devoutly believe an OAG is superior to a guidescope.

BTW, here's a shot of my imaging set up:

80mm guidescope on 12" LX200


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tommax
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Re: LX200 GPS and auto guiding new [Re: *skyguy*]
      #5728695 - 03/12/13 05:52 PM

Quote:

I've used an 80mm f/4 guidescope ... with an Orion SSAG connected directly to the guide port ... on my 12" LX200 @f/6.3 for years with great results. Before that, I suffered for a long time using an OAG ... I could never get my scope to guide properly, even when I could find a suitable guide star. After switching to a guidescope ... dare I say it ... guiding actually became, FUN!

That said, the 50mm guidescope might be a little too small if you plan on imaging at a focal length much over 1500mm. Other then that, you'll probably find autoguiding easier to learn and do using a guidescope instead of an OAG. However, you will find astrophotograhers who devoutly believe an OAG is superior to a guidescope.

BTW, here's a shot of my imaging set up:

80mm guidescope on 12" LX200





Nice setup!

What do you have there for a focuser? I know one of my complaints with my LX200GPS is the focuser... no way to really fine tune focus for photography (viewing is fine). I have been looking at different options from ones that have numbers to motorized... I have not seen anything like yours. I am feeling kind of partial at the moment to one I saw that was a 2 speed but I don't think there is a way to automate that one...


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*skyguy*
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Re: LX200 GPS and auto guiding new [Re: tommax]
      #5728740 - 03/12/13 06:22 PM

Quote:

Quote:

I've used an 80mm f/4 guidescope ... with an Orion SSAG connected directly to the guide port ... on my 12" LX200 @f/6.3 for years with great results. Before that, I suffered for a long time using an OAG ... I could never get my scope to guide properly, even when I could find a suitable guide star. After switching to a guidescope ... dare I say it ... guiding actually became, FUN!

That said, the 50mm guidescope might be a little too small if you plan on imaging at a focal length much over 1500mm. Other then that, you'll probably find autoguiding easier to learn and do using a guidescope instead of an OAG. However, you will find astrophotograhers who devoutly believe an OAG is superior to a guidescope.

BTW, here's a shot of my imaging set up:

80mm guidescope on 12" LX200





Nice setup!

What do you have there for a focuser? I know one of my complaints with my LX200GPS is the focuser... no way to really fine tune focus for photography (viewing is fine). I have been looking at different options from ones that have numbers to motorized... I have not seen anything like yours. I am feeling kind of partial at the moment to one I saw that was a 2 speed but I don't think there is a way to automate that one...




I have a Technical Innovations RoboFocus installed on the scope's stock focusing knob. It's run by the observatory computer and will automatically compensate for backlash in the system once it's properly trained. It will also find the perfect focus in seconds ... far more accurately and quickly then I was ever able to do by hand. Robofocus is a very popular automated fousing system used by many astrophotograpers:

RoboFocus


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Markigno
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Re: LX200 GPS and auto guiding new [Re: *skyguy*]
      #5728791 - 03/12/13 06:48 PM

Hi, OAG is the correct way for guiding an LX200. You need to plan the photo session with a good planetarium that allows you to change the FOV according to your main camera/guide camera. Take an OAG which is rotatable 360, or create a system that can do turn the block OAG/camera. This is the secret for find always a guide star with OAG. Also, if you want, with an Oag you can use an adaptive optics.
Marco

Edited by Markigno (03/12/13 06:50 PM)


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