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Edge 11 dovetail on top for adding weight-balance and for guide scope? RA finders?

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#1 markm75c

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Posted 06 September 2019 - 09:50 AM

Still fairly new to my edge 11 and gem cem 120 (first gem), lots to learn here.

 

In balancing the cem120 on its dec axis, i'm finding that its back end heavy, needs slid pretty far forward, roughly 5 of the circles on the saddle on the cem120 which puts it beyond the 3rd tightening knob, so basically if i slide it to where i think it needs to be, only two knobs are holding things in place, which from other discussions is fine.

 

Another person has a dovetail on the top, at least i think it is, with some sort of weight attachment there at the end to balance things.  I believe this is the approach ill take, as i'm not sure if there is enough lower dovetail to put one of these on.  I think this is the weight?

 

I see many using the standard? dovetail on the top plus some sort of inner rail i think, for attaching say an 80mm guidescope?  I'm trying to be sure on which dovetail model this is on top and anything else ill need if i later put an 80mm guidescope on top.

 

(I may eventually try OAG, as many said its better in the long run, but either way i think i need this bar on top)

 

Anyone have any pics of such a layout with weights on the top/guide scope?  Would this be the right model dovetail bar (cge 94219) at least, for on the top?

 

The second part of the question is on the finder scope.  I put my old celestron 9x50 Corrected RA finder on the edge 11 (illuminated cross hair type).  This is fine most of the time, but depending on the angle the mount is in, it can be a bit hard to get at the eyepiece of the finder.  (the mount center is around 52.5" off the deck floor and even for my 6'6 height it can be interesting at times so far).  Are most people using straight on finders with the 11 and not right angle ones?

 

Thanks in advance for any info here

 



#2 rgsalinger

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Posted 06 September 2019 - 10:08 AM

First of all you are wasting your time trying to use a guide scope with an SCT of that focal length. You need an OAG. You will get differential flexure and you will NOT get measurably round stars. The easy way to balance the mount is to buy a weight system from ADM. You can find these at https://www.admacces...hts-mds-series/ That's what I use on a similar scope with the same issue - back heavy. These attach to the bottom dovetail and can be slid up/down to get good DEC balance. 

Rgrds-Ross 


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#3 markm75c

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Posted 06 September 2019 - 10:27 AM

First of all you are wasting your time trying to use a guide scope with an SCT of that focal length. You need an OAG. You will get differential flexure and you will NOT get measurably round stars. The easy way to balance the mount is to buy a weight system from ADM. You can find these at https://www.admacces...hts-mds-series/ That's what I use on a similar scope with the same issue - back heavy. These attach to the bottom dovetail and can be slid up/down to get good DEC balance. 

Rgrds-Ross 

Ok, yes i've read that flexture makes a guidescope rather difficult at this length.  I was going to consider (later) getting the celestron OAG plus the 178MM camera (unless there is a less expensive but good camera choice).

 

On the adm link you had there, i think those arent right? Or at least not the same as the one i linked.  The one i linked here has a 4" gap to grab onto the dovetail bar?  Is that 4" not correct, vs the one you linked that has 2" gap?  I was concerned there woudlnt be enough of the lower dovetail sticking out to grab onto to put this adm weight, hence the top idea, but maybe there is, i can just get this adm weight and test first.



#4 Rustler46

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Posted 07 September 2019 - 01:54 AM

No doubt a guide 'scope can give you problems at times. But I have used a small 50mm guide 'scope atop my C-11 (non-Edge) at f/7.1, around 1990 mm focal length. Here's an image that's a stack of 12 exposures of 5 minutes each:

 

M51 Stacked.jpg

Sony NEX-5N, ISO 1600

 

The image is nothing special. But it shows that it's possible to get round stars with a small guide 'scope riding piggyback. The telescope has stock orange Celestron dovetails, top and bottom. A heavier guide 'scope like an 80 mm might be enough to cause flexure, that was not experienced with a lighter 'scope. No doubt that an OAG produces consistent superior results. Though I've never used one, I hear it does have its own set of challenges. 

 

Best Regards,

Russ


Edited by Rustler46, 07 September 2019 - 01:58 AM.

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#5 rgsalinger

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Posted 07 September 2019 - 12:50 PM

Now, I'm not saying that you are getting "bad" results, rather that if you measured the quality of the stars in that shot, you would see that they are just not round. This is kind of what bothers me about a lot of threads where guiding is discussed. You can be objective or subjective and if you like your results, well you like your results. To me, without a quantitative measurement we are often talking through each other rather than to each other.

 

Here's a heavily cropped piece of an image I took last night. It's a little rough as it's only 2 hours of integration time but this is what I mean by nice round stars. 

 

 

NGC650.jpg

 

 

Of course, the mount, scope, etc all matter but to me, this is very obtainable with the right guiding equipment.

 

Rgrds-Ross


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#6 NMBob

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Posted 07 September 2019 - 02:38 PM

I got the VC11-O-V from ADM for the top of my C11. I haven't figured out any kind of guiding, yet, but I've used it for a battery pack and ZWO ASiair computer when my ZWO camera is on the front with a HyperStar lens. I'd use it for counterweights if necessary, but I don't have any of the parts yet. Most C-somethings need to to be moved pretty far forward in the saddle, so in most cases there should be room for a clamped-on counterweight on the bottom dovetail.



#7 MHamburg

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Posted 09 September 2019 - 10:05 AM

Mark,

I have an Edge 11HD on a CGEM on a permanent pier. I put an ADM rail on top to mount occasionally my Orion 80mm ED for wide® FOV photography while guiding with the Edge.

Michael

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#8 markm75c

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Posted 11 September 2019 - 02:43 PM

I got the VC11-O-V from ADM for the top of my C11. I haven't figured out any kind of guiding, yet, but I've used it for a battery pack and ZWO ASiair computer when my ZWO camera is on the front with a HyperStar lens. I'd use it for counterweights if necessary, but I don't have any of the parts yet. Most C-somethings need to to be moved pretty far forward in the saddle, so in most cases there should be room for a clamped-on counterweight on the bottom dovetail.


The top bar is this one correct? (I may need one for an adm weight set i ordered if not enough room on the lower bar)
https://www.admacces...range-anodized/

How does that bar compare to this cheaper cge bar?
https://www.highpoin...etail-bar-94219

#9 markm75c

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Posted 11 September 2019 - 02:48 PM

somewhat silly question about running phd2 if not guiding to determine RMS/error..

Since many are saying OAG is the way to go vs say the 80mm scope + guide camera, what do you do if you dont have OAG to have PHD2 running during sessions to look for RA error?
I'm guessing (obviously), just using the camera in the main OTA and testing it that way or at the same time as imaging (i dont think both can occur at the same time right?)

In this case, i guess the best bet is to dive into OAG to be able to have this functionality during imaging sessions?

For those running OAG, whats the best bet there for camera + oag system for the edge 11? Still the celestron OAG + 174mm mini or some other variant?

#10 kingjamez

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Posted 11 September 2019 - 02:56 PM

somewhat silly question about running phd2 if not guiding to determine RMS/error..

Since many are saying OAG is the way to go vs say the 80mm scope + guide camera, what do you do if you dont have OAG to have PHD2 running during sessions to look for RA error?
I'm guessing (obviously), just using the camera in the main OTA and testing it that way or at the same time as imaging (i dont think both can occur at the same time right?)

In this case, i guess the best bet is to dive into OAG to be able to have this functionality during imaging sessions?

For those running OAG, whats the best bet there for camera + oag system for the edge 11? Still the celestron OAG + 174mm mini or some other variant?

The celestron OAG + 174mm is a good option. 

 

As to you question of "what do you do if you don't have an OAG"... there isn't anything you can do except use the guidescope but you won't get round stars. The stars may be better than if you went unguided, but you will likely not have anything useable either way.

 

-Jim


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#11 markm75c

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Posted 11 September 2019 - 03:21 PM

The celestron OAG + 174mm is a good option. 
 
As to you question of "what do you do if you don't have an OAG"... there isn't anything you can do except use the guidescope but you won't get round stars. The stars may be better than if you went unguided, but you will likely not have anything useable either way.
 
-Jim


Thats what i figured, so i'm best off to start planning on getting the oag and guide camera (and anything else that might be needed to make it fit with my 294mc i guess). Might as well jump on in and do it right smile.gif

I guess on not having round stars, though, is this for captures longer than 5 minutes or for shorter ones as well? Not sure that OAG has much effect for doing hyperstar imaging but certainly f7?

Edited by markm75c, 11 September 2019 - 03:22 PM.


#12 kingjamez

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Posted 11 September 2019 - 04:17 PM

Thats what i figured, so i'm best off to start planning on getting the oag and guide camera (and anything else that might be needed to make it fit with my 294mc i guess). Might as well jump on in and do it right smile.gif

I guess on not having round stars, though, is this for captures longer than 5 minutes or for shorter ones as well? Not sure that OAG has much effect for doing hyperstar imaging but certainly f7?

It depends on your mount. With today's tiny pixeled cameras, the focal ratio doesn't matter as much as it used to. I get oblong stars on my RASA8 if I don't guide and it's only 400mm, but my image scale is 1.24"/pixel. 

 

We often talk about guiding difficulty by length of exposure and focal length but those are abstracted issues from the real issue: Positional error. Guiding time makes a difference because there is less opportunity in 60 seconds than in 300 seconds to get a large (in relation to image scale) positional error.

 

My CEM60 has about +/- 6 arc seconds of error over its 300 second worm rotation. That means if I do a 5 minute sub it'll have 12 arc seconds of error. If you take some subset of that error over 60 seconds, it can still be 6-8 arc seconds since my peak to valley time is about 2 minutes (think of the error as a sine wave). 

 

6-8 arc seconds of error is just as bad as 12 arc seconds of error when my image scale is 1.24 arc seconds. Both images would be completely useless. For round stars, you should shoot for guiding errors on RA/DEC to be about equal and both about 1/2 in RMS of your image scale. 

 

To that end, you need to guide, simple as that. The only way to guide with good results on a SCT at small images scales is an OAG.

 

-Jim 



#13 markm75c

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Posted 11 September 2019 - 04:26 PM

It depends on your mount. With today's tiny pixeled cameras, the focal ratio doesn't matter as much as it used to. I get oblong stars on my RASA8 if I don't guide and it's only 400mm, but my image scale is 1.24"/pixel. 

 

We often talk about guiding difficulty by length of exposure and focal length but those are abstracted issues from the real issue: Positional error. Guiding time makes a difference because there is less opportunity in 60 seconds than in 300 seconds to get a large (in relation to image scale) positional error.

 

My CEM60 has about +/- 6 arc seconds of error over its 300 second worm rotation. That means if I do a 5 minute sub it'll have 12 arc seconds of error. If you take some subset of that error over 60 seconds, it can still be 6-8 arc seconds since my peak to valley time is about 2 minutes (think of the error as a sine wave). 

 

6-8 arc seconds of error is just as bad as 12 arc seconds of error when my image scale is 1.24 arc seconds. Both images would be completely useless. For round stars, you should shoot for guiding errors on RA/DEC to be about equal and both about 1/2 in RMS of your image scale. 

 

To that end, you need to guide, simple as that. The only way to guide with good results on a SCT at small images scales is an OAG.

 

-Jim 

Thats a good point on image scale and rms.  Ill have to figure out what that comes out to depending on the camera, would be useful to know.  

 

I just saw though, that people still use a guide scope and camera (thinking zwo 60mm and asi290mm mini) with hyperstar due to the wider field, since obviously oag wont help there, so sounds like i'm planning on both.



#14 jhayes_tucson

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Posted 11 September 2019 - 06:24 PM

No doubt a guide 'scope can give you problems at times. But I have used a small 50mm guide 'scope atop my C-11 (non-Edge) at f/7.1, around 1990 mm focal length. Here's an image that's a stack of 12 exposures of 5 minutes each:

 

attachicon.gif M51 Stacked.jpg

Sony NEX-5N, ISO 1600

 

The image is nothing special. But it shows that it's possible to get round stars with a small guide 'scope riding piggyback. The telescope has stock orange Celestron dovetails, top and bottom. A heavier guide 'scope like an 80 mm might be enough to cause flexure, that was not experienced with a lighter 'scope. No doubt that an OAG produces consistent superior results. Though I've never used one, I hear it does have its own set of challenges. 

 

Best Regards,

Russ

 

Russ,

You are right that you can get round stars with a guide scope but that's not the most important thing.  Getting small stars is what is important and minimizing FWHM with a guide scope on a SCT is not likely.

 

John


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#15 dmdouglass

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Posted 11 September 2019 - 07:08 PM

Russ,

You are right that you can get round stars with a guide scope but that's not the most important thing.  Getting small stars is what is important and minimizing FWHM with a guide scope on a SCT is not likely.

 

John

John... i am usually "right there with you"...  but i think i would challenge this one just a little.

For ME....  the "most important thing" is simply getting out under the stars, and seeing our "targets" as best we can, either visual or with imaging.

 

Now....  for an "artist", or "perfectionist", or "master of the art of astro imaging"... (and i consider you as one of the later)

then YES... small round stars...   and BEAUTIFUL IMAGES (as you always produce, and which i enjoy viewing).



#16 Rustler46

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Posted 11 September 2019 - 09:33 PM

John... i am usually "right there with you"...  but i think i would challenge this one just a little.

For ME....  the "most important thing" is simply getting out under the stars, and seeing our "targets" as best we can, either visual or with imaging.

 

Now....  for an "artist", or "perfectionist", or "master of the art of astro imaging"... (and i consider you as one of the later)

then YES... small round stars...   and BEAUTIFUL IMAGES (as you always produce, and which i enjoy viewing).

 

Russ,

You are right that you can get round stars with a guide scope but that's not the most important thing.  Getting small stars is what is important and minimizing FWHM with a guide scope on a SCT is not likely.

Hi John,

Thanks for your comment. I always enjoy the insight you offer on the subject under discussion. Other than lunar/planetary and meteors I don't do much astrophotography nowadays. But when I did image DSOs I was just happy to get an image that I enjoyed. One of my favorites is an image of M13 with a 10-inch reflector. You don't really have to zoom in much to see that it has significant trailing. It certainly won't win any prizes. Still the overall view is spectacular in my assessment.

 

M13 - Stack 1-.jpg

The Great Globular Cluster in Hercules - Best viewed from afar. 

10-inch reflector w/ coma corrector, f/5.5, stack of 24 8-minute images at ISO 800, Sony NEX-5N

I don't think this had any auto-guiding, just PEC on the G-11 mount.

 

We all have our standards as to what is an acceptable astro-photo. My point of view has been if you can see a disturbing flaw when zoomed in (pixel-peeping), then don't zoom in. Yet I realize other ones in their pursuit of perfection are not satisfied with their image, if it can be made better. The result of that paradigm is evident in the spectacular, near-perfect images produced by many amateurs today. These I applaud for their attention to detail.

 

You are right that it is possible (not easy) to get round stars with a guide 'scope. Yet even OAG has its limitations. For example one has a limited selection of guide stars from which to choose. A guide scope gives the flexibility of not pointing exactly in the same direction as one's imaging subject. Also a short focal length guide scope can give a wider FOV from which to pick guide stars. Of course these features are not without their negatives. A short focal length guide 'scope requires a very good mount to respond quickly to tiny deviations from perfect tracking. For every choice we make there are positives and negatives.

 

John, part of your comment I don't fully understand. That is "Getting small stars is what is important and minimizing FWHM with a guide scope on a SCT is not likely". What puzzles me is that getting tiny stars has to do in part with near perfect focus, not just how guiding is accomplished. It seems that both fine focus and good guiding is necessary to have small, round stars. I think I get it that round stars (produced by a guide 'scope) may not be tiny stars. But would you enlarge on your comments for our benefit?

 

On another point I agree with David's statement - "For ME....  the "most important thing" is simply getting out under the stars, and seeing our "targets" as best we can, either visual or with imaging." Amen to that!

 

Best Regards,

Russ


Edited by Rustler46, 11 September 2019 - 09:51 PM.


#17 kingjamez

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Posted 11 September 2019 - 09:43 PM

 

 

John, part of your comment I didn't understand. That is "Getting small stars is what is important and minimizing FWHM with a guide scope on a SCT is not likely". What puzzles me is that getting tiny stars has to do in part with near perfect focus, not just how guiding is accomplished. Would you enlarge on your comments for our benefit?

 

 

I'm not John, and I'm sure he'll come in and say it better than I could...

 

It's assumed that you have good focus. If you have good focus, but the stars are moved randomly around from tracking errors, they can still appear round but just larger than they would have been if the tracking had been "perfect". Bad tracking and bad seeing destroys resolution of fine details and just because the stars are round doesn't mean the tracking was good.

 

If one axis has a different amount of error than the other axis, then you'll get oblong stars. This is more obviously "bad" than round stars that are just big. This thread has good examples of both. 

 

-Jim


Edited by kingjamez, 11 September 2019 - 09:44 PM.

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#18 Rustler46

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Posted 11 September 2019 - 10:29 PM

I'm not John, and I'm sure he'll come in and say it better than I could...

 

It's assumed that you have good focus. If you have good focus, but the stars are moved randomly around from tracking errors, they can still appear round but just larger than they would have been if the tracking had been "perfect". Bad tracking and bad seeing destroys resolution of fine details and just because the stars are round doesn't mean the tracking was good.

 

If one axis has a different amount of error than the other axis, then you'll get oblong stars. This is more obviously "bad" than round stars that are just big. This thread has good examples of both. 

Thanks, Jim. That makes a lot of sense. I hope John will check in on this as well. But your comment brings to mind the following - Why "minimizing FWHM with a guide scope on a SCT is not likely" (John's words). What is it about the SCT/guide-scope combo that makes it unlikely? Perhaps you or John can enlighten us. It bears on the trade-offs of guide 'scope versus OAG.

 

Russ



#19 markm75c

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Posted 11 September 2019 - 10:34 PM

The top bar is this one correct? (I may need one for an adm weight set i ordered if not enough room on the lower bar)
https://www.admacces...range-anodized/

How does that bar compare to this cheaper cge bar?
https://www.highpoin...etail-bar-94219

I wanted to jump back to my question here. Can anyone point out why I would choose one of these over the other. I'll either have a 60 or 80mm guidescope on top plus I just bought the ADM d series weights though those will hopefully fit on the lower plate but I think if not they need the cge plates width. So I guess the choice is cge here?

 

The ADM option I think is vixen size. 


Edited by markm75c, 11 September 2019 - 10:35 PM.


#20 kingjamez

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Posted 11 September 2019 - 10:35 PM

Thanks, Jim. That makes a lot of sense. I hope John will check in on this as well. But your comment brings to mind the following - Why "minimizing FWHM with a guide scope on a SCT is not likely" (John's words). What is it about the SCT/guide-scope combo that makes it unlikely? Perhaps you or John can enlighten us. It bears on the trade-offs of guide 'scope versus OAG.

Russ

Differential flexture and mirror flop are why an OAG works better on an SCT. Both of those will cause the FWHM (a diameter measurement of where the stars brightness is half its peak) to grow due to differences between the guide scopes view and imaging scopes view. This is independent of any actual tracking errors from the mount. If the guide scope is behaving differently than the imaging scope, it will cause errors, not eliminate them.
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#21 kingjamez

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Posted 11 September 2019 - 10:38 PM

I wanted to jump back to my question here. Can anyone point out why I would choose one of these over the other. I'll either have a 60 or 80mm guidescope on top plus I just bought the ADM d series weights though those will hopefully fit on the lower plate but I think if not they need the cge plates width. So I guess the choice is cge here?

The ADM option I think is vixen size.

I use the Celestron CGE bar on top and bottom of my RASA and C11. I like them and can’t see a reason to use anything else.
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#22 jhayes_tucson

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Posted 11 September 2019 - 11:07 PM

Hi John,

Thanks for your comment. I always enjoy the insight you offer on the subject under discussion. Other than lunar/planetary and meteors I don't do much astrophotography nowadays. But when I did image DSOs I was just happy to get an image that I enjoyed. One of my favorites is an image of M13 with a 10-inch reflector. You don't really have to zoom in much to see that it has significant trailing. It certainly won't win any prizes. Still the overall view is spectacular in my assessment.

 

attachicon.gif M13 - Stack 1-.jpg

The Great Globular Cluster in Hercules - Best viewed from afar. 

10-inch reflector w/ coma corrector, f/5.5, stack of 24 8-minute images at ISO 800, Sony NEX-5N

I don't think this had any auto-guiding, just PEC on the G-11 mount.

 

We all have our standards as to what is an acceptable astro-photo. My point of view has been if you can see a disturbing flaw when zoomed in (pixel-peeping), then don't zoom in. Yet I realize other ones in their pursuit of perfection are not satisfied with their image, if it can be made better. The result of that paradigm is evident in the spectacular, near-perfect images produced by many amateurs today. These I applaud for their attention to detail.

 

You are right that it is possible (not easy) to get round stars with a guide 'scope. Yet even OAG has its limitations. For example one has a limited selection of guide stars from which to choose. A guide scope gives the flexibility of not pointing exactly in the same direction as one's imaging subject. Also a short focal length guide scope can give a wider FOV from which to pick guide stars. Of course these features are not without their negatives. A short focal length guide 'scope requires a very good mount to respond quickly to tiny deviations from perfect tracking. For every choice we make there are positives and negatives.

 

John, part of your comment I don't fully understand. That is "Getting small stars is what is important and minimizing FWHM with a guide scope on a SCT is not likely". What puzzles me is that getting tiny stars has to do in part with near perfect focus, not just how guiding is accomplished. It seems that both fine focus and good guiding is necessary to have small, round stars. I think I get it that round stars (produced by a guide 'scope) may not be tiny stars. But would you enlarge on your comments for our benefit?

 

On another point I agree with David's statement - "For ME....  the "most important thing" is simply getting out under the stars, and seeing our "targets" as best we can, either visual or with imaging." Amen to that!

 

Best Regards,

Russ

 

Russ,

As others have pointed out, differential flexure is a common problem with larger SCTs like a C11.  The other problem is achieving the sensitivity that you need to minimize guide errors using a small guide scope. It's entirely possible to get pretty round stars with a guide scope on a C11, but in general, it's pretty hard to get stars as small as you'll get by guiding through the scope, which eliminates both problems.  The other problem with guide scope guiding is the it typically limits the length of your subs and that's not the case with though the scope guiding.  In both cases, I'm assuming that the image is properly focused.

 

There is no doubt that it's pretty easy to just use a guide scope for guiding; but, in reality, it's not very much harder to simply guide through the scope in the first place.  The improvement in quality and yield makes it more than worthwhile to switch to OAG or ONAG for guiding.  It does require getting up out of your comfort zone to make a change but once you've done it, you'll find that it's just not that hard!

 

I've guided my C14 with a guide scope (here's a result:  https://www.astrobin...page=3&nc=&nce=) and with ONAG (here's the same object:https://www.astrobin.com/flowqa/?nc=user).  The results that I achieved with the guide scope never came close to what I get by guiding through the scope--no mater how careful I was.  And with the guide scope, I could never go more than about 3 minutes for my subs before flexure started to screw things up.  With my current system I typically use 20 minute exposures and I could go for 60 min if that made any sense.   And I won't even begin to talk about yield.

 

John


Edited by jhayes_tucson, 12 September 2019 - 09:37 AM.

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#23 MikeMiller

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Posted 12 September 2019 - 09:49 AM

I only use a guidescope on my EdgeHD 8 when using Hyperstar. At all other times I use OAG. But even then, rails on the top and bottom are pretty common.

 

I had used an orange Losmandy top-rail, which let me swap between Vixen and Losmandy mounts easily. 

 

My current iteration uses a TSS tube rings for extra stability. Auto focus makes a big difference too. Before autofocus there were plenty of times I looked at a sample image and decided "yeah, that focus is good enough", only to find out I have donut-shaped stars. Now I can have it redo focus every x minutes.

 

From AVX Unguided to Mach1 Guided; basically it its like a completely different scope.

 

post-230739-0-24670300-1533875205_thumb.jpg


Edited by MikeMiller, 12 September 2019 - 09:52 AM.


#24 markm75c

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Posted 12 September 2019 - 10:01 AM

I only use a guidescope on my EdgeHD 8 when using Hyperstar. At all other times I use OAG. But even then, rails on the top and bottom are pretty common.

 

I had used an orange Losmandy top-rail, which let me swap between Vixen and Losmandy mounts easily. 

 

My current iteration uses a TSS tube rings for extra stability. Auto focus makes a big difference too. Before autofocus there were plenty of times I looked at a sample image and decided "yeah, that focus is good enough", only to find out I have donut-shaped stars. Now I can have it redo focus every x minutes.

 

From AVX Unguided to Mach1 Guided; basically it its like a completely different scope.

 

attachicon.gif post-230739-0-24670300-1533875205_thumb.jpg

So you swap back and forth from the telrad to the guidescope i take it?

 

On the top of mine right now i have a dslr piggy back adapter, which i'm only using for putting on the small red dot finder i have.  I have a right angle 9x50 with cross hairs for the main finder.  I was planning on leaving both of these attached (somehow) and adding the central CGE D series bar in the middle i guess.  

I'd already ordered the cge bar.

 

I was thinking of going with something like this generic 60mm guidescope for hyper

https://www.ebay.com...6MAAOSwt3hb~6Lf

 

edit: not the above one, but the svbony sv106 that others seem to report success with located here on amazon for $80.  I'm not sure what the best way to attach the asi290mm mini to this is though, i thought it had a 1.25" ability but it shows m42x.75 on the end, so maybe with some other adapter (m42-1.25 )

 

But i'm not sure how that can be attached to the D series? looks to be V rings and bar at bottom but no clamp?

Do i just need some sort of D to V clamp?

 

EDIT: something like this at $120? https://www.highpoin...e-rings-dvr-125

Seems a bit pricey but this is probably needed though, to avoid flexture even with hyperstar?  Ends up a net cost of about $180 for the finder/rings if this is right.


Edited by markm75c, 12 September 2019 - 02:18 PM.


#25 kingjamez

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Posted 12 September 2019 - 01:02 PM

On my RASA I use a Geoptik lens to t-thread adapter with a Nikon ED 180mm F/2.8 camera lens connected to an ADM dovetail clamp: https://optcorp.com/...XwaAlOvEALw_wcB

 

I mount it on the underside front of the RASA and use an ASI290mm as a camera. This DOES NOT WORK with my C11, but works fine at 400mm and I get good guiding with small stars.


Edited by kingjamez, 12 September 2019 - 01:03 PM.



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