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Celestron Advanced VX advice.

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#1 ArandomPilot

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Posted 14 July 2020 - 03:26 PM

I recently bought a Celestron AVX mount to begin AP. I am soon going to buy the scope (Orion Eon 115, camera is SBIG ST-2000XM, total weight should be around 20lbs for optical train). I am fairly new to EQ mounts, and today was finally able to focus the polar scope while not making the Octans and constellations disappear. So I am looking for tips and tricks for the AVX mount. I'm still going over the features of the mount and getting used to it. I am still having a hard time finding Polaris (unsure which one is Polaris), not sure about the polar align feature. There's a whole lot to this mount I am unsure of, but its cool to slew around and try to point it at certain objects. Any tips I should know?

 

Thanks,

Gabe.



#2 WadeH237

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Posted 14 July 2020 - 03:52 PM

If you've not bought the scope yet, my biggest suggestion is to hold off to do some more research.

 

In my opinion, that scope is too much for the AVX.  It's not just a matter of weight.  That size scope has a long moment arm and will be difficult for the mount to handle unless conditions are perfect.  Also, it's a considerably longer focal length than I would suggest for an AVX (or for learning to image).

 

My standard suggestion for imaging with an AVX is to go with an 80mm or smaller refractor.  The longest focal length I would recommend is 600mm, but 480mm is even better.  An 80mm, F/6, triplet refractor is probably an ideal match for deep sky imaging on an AVX.

 

And even with that scope, you should plan on a guide scope and camera as well.  I know that the ST-2000 has a built-in guide chip, but it sounds like you have the mono version of the camera.  If that's the case, then that guide camera is behind the filters.  This is not a problem for the luminance filter, but color filters will be hit and miss on getting guide stars, especially the blue filter.  And narrow band filters won't work well at all in that configuration.

 

I'll, though, that for visual use, the AVX is a great little mount.  It'll handle an 8" SCT like it's not even there.  Some people push the weight up to a C11 with acceptable (visual) results.


Edited by WadeH237, 14 July 2020 - 03:54 PM.

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#3 aa6ww

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Posted 14 July 2020 - 04:03 PM

Ive seen the AVX mount with an AT-115 on it with camera's and guide scope and stability was never an issue. It used two 11 pound counterweights.

The legs were fully retracted when I saw this configuration and the owner was completely happy with his set up. AVX mounts seem to be the testing mount for new astrophotographers. The come and go daily for sale. I have one with StarSense and its a very robust small mount with bullseye accuracy.

I use an SW-120ED on mine and my C8 HD

 

 

 

...Ralph



#4 Michael Covington

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Posted 14 July 2020 - 04:16 PM

It's a good idea to spend some time learning the sky if you are having trouble identifying Polaris.   Octans is a southern hemisphere constellation that is used when people south of the equator are polar-aligning; it is not visible from Colorado.


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#5 MJB87

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Posted 14 July 2020 - 04:27 PM

There are numerous iPhone/Android apps that allow you to look at the sky and to learn what stars you are looking app. One of these would be a worthwhile investment until you learn to read the sky.

 

As for the AVX, you may be pushing the limits for your setup but you should be OK. I put an A-P 130mm EDFS on my AVX and had a lot of fun with it, while I waited for my 1100GTO to arrive.

 

I would suggest you consider a camera that allows you to do relatively quick exposures since precision guiding with your setup will likely be a challenge for more than 60 seconds or so.


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#6 gene williams

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Posted 14 July 2020 - 04:29 PM

I recently bought a Celestron AVX mount to begin AP. I am soon going to buy the scope (Orion Eon 115, camera is SBIG ST-2000XM, total weight should be around 20lbs for optical train). I am fairly new to EQ mounts, and today was finally able to focus the polar scope while not making the Octans and constellations disappear. So I am looking for tips and tricks for the AVX mount. I'm still going over the features of the mount and getting used to it. I am still having a hard time finding Polaris (unsure which one is Polaris), not sure about the polar align feature. There's a whole lot to this mount I am unsure of, but its cool to slew around and try to point it at certain objects. Any tips I should know?

 

Thanks,

Gabe.

Let us know how it works out.  I always assumed the AVX was good up to about an 80mm f/6 or perhaps a 100mm f/6.  Seems a little high on the weight, but then again, I have never pushed the AVX beyond a William Optics GTF-81 at 535mm focal length with a DSLR and guidescope.  For that setup, it was very good.  

 

With your Orion Eon 115, you will be right at about 1.9 arc seconds per pixel, which should be a bit forgiving, and if you use a reducer instead of a straight flattener, you will be a little over 2 arc seconds per pixel, even better for guiding errors.  You might have to throw out a lot of subs, but subs are cheap.  I have the AVX, and am interested in hearing your experience.  But as WadeH has mentioned, you may want to consider a smaller refractor to start your journey.  Just my two cents


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#7 vsteblina

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Posted 14 July 2020 - 04:50 PM

Ive seen the AVX mount with an AT-115 on it with camera's and guide scope and stability was never an issue. It used two 11 pound counterweights.

The legs were fully retracted when I saw this configuration and the owner was completely happy with his set up. AVX mounts seem to be the testing mount for new astrophotographers. The come and go daily for sale. I have one with StarSense and its a very robust small mount with bullseye accuracy.

I use an SW-120ED on mine and my C8 HD

 

 

 

...Ralph

I have used my AVX with a AT115EDT and a ST-8XE camera.  I only needed one counterweight but it was real close and I have bought a second counterweight.

 

It worked just fine. 

 

It does work better with a guider, but that is dependent on polar alignment.  Read the part in the AVX manual on how to do a polar alignment by using the hand paddle.  There are also some instructions on the web on doing this that might be clearer.

 

I bought it from Starzonia and he recommended NOT buying the polar finder.  Just to do the polar alignment using the hand paddle. 

 

To find Polaris, use the compass in your phone, or get a old-fashioned magnetic compass.  Don't feel bad.  When I started to learn the constellations I mistook Orion for the Big Dipper!!!  Hey, I was 13 and it was a light polluted sky.

 

IF you have a Canon or Nikon camera get Backyard EOS or Backyard Nikon and use that camera as a piggyback mount on the Orion EON as you get started.  That will save you time in the long run!!!

 

The AVX and 115 is a good combination. 


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#8 ArandomPilot

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Posted 14 July 2020 - 11:59 PM

I have used my AVX with a AT115EDT and a ST-8XE camera.  I only needed one counterweight but it was real close and I have bought a second counterweight.

 

It worked just fine. 

 

It does work better with a guider, but that is dependent on polar alignment.  Read the part in the AVX manual on how to do a polar alignment by using the hand paddle.  There are also some instructions on the web on doing this that might be clearer.

 

I bought it from Starzonia and he recommended NOT buying the polar finder.  Just to do the polar alignment using the hand paddle. 

 

To find Polaris, use the compass in your phone, or get a old-fashioned magnetic compass.  Don't feel bad.  When I started to learn the constellations I mistook Orion for the Big Dipper!!!  Hey, I was 13 and it was a light polluted sky.

 

IF you have a Canon or Nikon camera get Backyard EOS or Backyard Nikon and use that camera as a piggyback mount on the Orion EON as you get started.  That will save you time in the long run!!!

 

The AVX and 115 is a good combination. 

I mistook the Pleiades for the little dipper. That was about a little over a year ago. I know the constellation in which Polaris sits in and can point my mount there, the problem is the polar scope. I have pointed it to true magnetic north and got a decent polar alignment (Was able to get Jupiter in between the mounting brackets). 



#9 ArandomPilot

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Posted 15 July 2020 - 12:03 AM

It's a good idea to spend some time learning the sky if you are having trouble identifying Polaris.   Octans is a southern hemisphere constellation that is used when people south of the equator are polar-aligning; it is not visible from Colorado.

I'm actually good with the constellations and can identify Polaris in Ursa Minor, just can't find it in the polar scope, but then again, I can't see the guides for polar alignment. I have gotten a decent polar alignment once while just pointing the mount to true magnetic north and got Jupiter between the mounting brackets (albeit not center, far from it, but an accomplishment in my book). I still want to get more accurate, but I can't tonight due to the heavy rainfall.



#10 ArandomPilot

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Posted 15 July 2020 - 12:39 AM

If you've not bought the scope yet, my biggest suggestion is to hold off to do some more research.

 

In my opinion, that scope is too much for the AVX.  It's not just a matter of weight.  That size scope has a long moment arm and will be difficult for the mount to handle unless conditions are perfect.  Also, it's a considerably longer focal length than I would suggest for an AVX (or for learning to image).

 

My standard suggestion for imaging with an AVX is to go with an 80mm or smaller refractor.  The longest focal length I would recommend is 600mm, but 480mm is even better.  An 80mm, F/6, triplet refractor is probably an ideal match for deep sky imaging on an AVX.

 

And even with that scope, you should plan on a guide scope and camera as well.  I know that the ST-2000 has a built-in guide chip, but it sounds like you have the mono version of the camera.  If that's the case, then that guide camera is behind the filters.  This is not a problem for the luminance filter, but color filters will be hit and miss on getting guide stars, especially the blue filter.  And narrow band filters won't work well at all in that configuration.

 

I'll, though, that for visual use, the AVX is a great little mount.  It'll handle an 8" SCT like it's not even there.  Some people push the weight up to a C11 with acceptable (visual) resT

The reason as to why I plan on getting the Orion EON 115 is to help with balance as the camera (ST-2000XM) weighs about 2 lbs (0.91Kg), I fear that a small scope like the Meade 70mm Quadruplet or Sky-Watcher 80mm is too light and will not balance right, I can only move the scope so far before the filter wheel bangs up against the mounting plate. If the guy with the refractor doesn't respond, I'll go with a small refractor like the Meade 70 Quad and use fishing sinkers to try and balance it out a bit or get an 8 inch Newt Astrograph from Orion. The last scope I do plan on getting before I go back to school is probably the Orion Ritchey-Chretien. Also, the 206 rule (Pixel size / by focal length * 206) would make any stars under 800mm focal length appear too soft; anything over 1400mm Focal length and the stars are blocky. Soft stars aren't the worst thing in the world, but pinpoint ones are the best. So my scopes are limited, but I do have experience with culmination, so a Newtonian isn't out of the picture.  



#11 gene williams

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Posted 15 July 2020 - 06:33 AM

I'm actually good with the constellations and can identify Polaris in Ursa Minor, just can't find it in the polar scope, but then again, I can't see the guides for polar alignment. I have gotten a decent polar alignment once while just pointing the mount to true magnetic north and got Jupiter between the mounting brackets (albeit not center, far from it, but an accomplishment in my book). I still want to get more accurate, but I can't tonight due to the heavy rainfall.

I am still "old school" when it comes to polar alignment, and have a lot of experience using the polar scope in the AVX.  I do not like having to align the mount for goto operation, and therefore, I never use the all star polar alignment routine.  I prefer the simplicity of turning the mount on, and going directly to sidereal tracking mode.  If you are interested, read on.  

 

First and foremost, you are going to need to align the polar scope to the mount's optical axis.  Take the mount outside in the daylight to perform this adjustment.  99 times out of 100, you will need to use a small allen wrench to adjust the set screws on the polar scope so the crosshairs do not move on a distant object.  Instructions can be found here on CN, and all are confusing - just be patient.  This will take a lot of time, so be prepared.  If you do not get the polar scope properly aligned so the crosshairs do not move on a distant object when rotating about the RA axis, any attempt to polar align using this method is futile.  

 

Once aligned, you can now use the Kochab Clock method to polar align.  Here is a link showing this very useful and EASY method to polar align without having to use apps, clocks, etc.  I love this method because you initially use the star in the Little Dipper (Kochab), and Polaris, and align them to the counterweight bar by sight, without having to look through the polar scope.  Just stand back a few feet from the counterweight bar, and sight Kochab and Polaris along a line formed by the counterweight bar.  Make small adjustments in RA to get this line perfect.  This method works because it just so happens that when you draw a line between Kochab and Polaris, the polar axis falls somewhere on that line (within approximately three quarters of a degree at the present).  You then look through the polar scope to do the fine adjustment. 

 

Once the polar scope is aligned, you will only need to perform a check before sundown each imaging session to ensure the polar scope has not been whacked out of alignment.  I have found it holds alignment really well, provided that the mount is handled gently.  

 

http://www.thestarde...Polaralign.html

 

That being said, my method has served me well for up to 5 minute subs autoguided on the AVX with a GTF81 at 535mm focal length.  I have never imaged with anything larger than that, nor have I imaged any longer subs than 5 minutes.  If I do in the future, I may use a different method, such as plate solving to get the polar alignment "dead on".  For now, however, this method has proven very reliable.  

 

P.S.  One other tip...it is very hard to see the reticle in the dark.  Take a small red led flashlight or headlamp.  I use my red headlamp to briefly illuminate the reticle, by placing the red led headlamp on the hole on the backside (i.e., the side of the mount opposite where you are looking through the polar scope) to illuminate the reticle.  It takes a bit of experimentation to get the level of illumination correct, but it is pretty easy.  You just want enough red light to see the crosshairs and the other parts of the reticle, and still be able to see Polaris for the alignment.  


Edited by gene williams, 15 July 2020 - 07:12 AM.


#12 mclewis1

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Posted 15 July 2020 - 08:04 AM

Or ... after setting up the mount (latitude set roughly and azimuth adjustment roughty centered) you point the mount roughly at Polaris, and if you can sight Polaris though the hole in the mount (without the polar alignment scope in place) using the latitude and azimuth adjustments. Then do a good 2 star initial alignment and start to add your calibration stars. Depending on your particular mount by the 3rd or 4th calibration star the star chosen should already be pretty much centered. Chose the last calibration star (3rd or 4th) as one high in the south (close to the celestial equator if possible). Then without moving off of that last calibration star do the polar alignment from the Alignment menu. By using that last calibration star you save your self the slew time and rough alignment on it.

 

The polar alignment routine in the Alignment menu is the ASPA (all star PA) everyone refers to. Follow the instructions, then unsync or re do your initial alignment (cycle the power or just replace your initial alignment stars) and you are done. If you are imaging and want the very best tracking you might re do the polar alignment routine again to ensure it's as accurate as you can get it.

 

I've found It is really helpful to identify and mark out the suitable initial alignment and calibration stars for each season (I keep single page charts for every two months). This way you can quickly choose the most suitable stars for each season and you get to know the more obscure ones which is often helpful in getting the most accurate initial alignment (choosing stars that are in the best positions rather than just the most popular ones).


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#13 mclewis1

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Posted 15 July 2020 - 10:42 AM

So basically it comes down to either putting the time and effort into initially configuring the polar alignment scope (PAS) and learning to use it accurately, and then keeping it in good alignment. When using the PAS the whole mount setup can be faster since there's no need to perform the ASPA routine or a second initial alignment.

 

Or spending a bit more time each time you setup doing the ASPA instead. 

 

Both will require ongoing practice to maintain the ability to get a good polar alignment.

 

But remember, for all of this discussion about polar alignment ... when you are just setting up the AVX for visual work you don't need to do any of this stuff ... just the initial alignment with the calibration stars. Polar alignment gives you good tracking and generally you only need that when you are imaging. A good initial alignment will give you good pointing accuracy (gotos) regardless of how far off (well, within reason) your polar alignment is.

 

There are some cases where being just reasonably well polar aligned can help. If you are in a hurry and want to do only a single star or solar system initial alignment, or if you want to do a solar system initial alignment during the daytime. In these cases being roughly polar aligned makes the automatic slewing to an alignment star or planet more accurate which saves you time. It doesn't however make the initial alignment done any more accurate, that is up to just how well you actually perform the initial alignment.


Edited by mclewis1, 15 July 2020 - 10:43 AM.

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#14 WadeH237

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Posted 15 July 2020 - 10:55 AM

I fear that a small scope like the Meade 70mm Quadruplet or Sky-Watcher 80mm is too light and will not balance right, I can only move the scope so far before the filter wheel bangs up against the mounting plate. 

This shouldn't be a problem.  The importance of balance is related to the moment of inertia, which is related to the amount of weight.  If the scope is too light to balance perfectly, it's probably light enough that an imbalance due to the camera being heavier than the scope is not that big a deal.  Just move the scope as far forward in the saddle as you can.


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#15 vsteblina

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Posted 15 July 2020 - 11:49 AM

This is the routine I use for polar alignment.

 

https://www.macobser...nment-procedure

 

More information on how to do this from other sources:

 

https://www.celestro...polar-alignment

 

https://stargazerslo...-mount-quickly/



#16 Don W

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Posted 15 July 2020 - 04:54 PM

I agree with Vladimir. I stopped using a polar scope several years ago. Very old school, not to mention a pain in the backside.

 

Use the Polar Alignment routines built into the handset. For visual use a 2 star alignment is sufficient. For imaging the ASPA is excellent.

 

Personally, I can image fine with a small scope. The 115 Eon might be a bit big.



#17 gene williams

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Posted 15 July 2020 - 07:43 PM

I agree with Vladimir. I stopped using a polar scope several years ago. Very old school, not to mention a pain in the backside.

 

Use the Polar Alignment routines built into the handset. For visual use a 2 star alignment is sufficient. For imaging the ASPA is excellent.

 

Personally, I can image fine with a small scope. The 115 Eon might be a bit big.

How many iterations do you need for the ASPA routine for imaging?  I have heard you need a couple of iterations, correct?  The reason I ask, I can be polar aligned for my modest application in less than 3 minutes, from the moment I turn on the handset, to being polar aligned.  At least for my particular modest setup. 



#18 Michael Covington

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Posted 15 July 2020 - 08:30 PM

For an accuracy of about 5 arc-minutes, I do a 6-star alignment, do ASPA, do another 6-star alignment, and ask myself whether it's close enough yet.  If not, I do ASPA again followed by a third 6-star alignment.

 

Reproduciblity is to about 5'.

 

For accuracy of about 1', use drift method or a Polemaster or iPolar, with a computer.


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#19 tomwall

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Posted 15 July 2020 - 09:13 PM

Here is a good video on ASPA. 

https://youtu.be/coXGvcgHOMA


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