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Celestron se5 ra axis Sharpcap

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#1 Luis franco

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Posted 18 August 2019 - 06:16 AM

Hi everyone, newbie here... i have a celestron se5 with (wedge) i recently bought a guide scope package with one year free sharpcap pro, i tried to polar align but when i get to the stage that it says to rotate the ra axis 90 degrees  i got lost and doesn't do anything at all, is there any kind soul able to provide some pictures or a video to show me what i have to do to try for a fair polar alignment using Sharpcap and this specific telescope.
Thanks in advance.
Sorry for my poor English
 



#2 Dynan

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Posted 18 August 2019 - 08:17 AM

What I do is to get the scope to its zero position (pointing toward the north celestial pole) and then rotate the RA axis until it is approximately 90° east or west. You can start by getting Polaris in your camera field of view...that's close enough. Rotate 90° east or west. On a wedge this would be the Azimuth movement. Then start SC polar align. It makes a plate solve then says rotate the scope 90°.

 

I then return the scope to the 'zero position', and SC plate solves again and reads out the PA error. With no 'zero position' on an SE5, you would need to closely estimate the return to the  NCP. Then adjust the scope watching the readout error. If the error gets larger, go the other way. You can do the same with a wedge mounted SE5.

 

Hope this helps.



#3 mclewis1

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Posted 18 August 2019 - 08:20 AM

Luis,

 

Welcome to CN. Your english in your post is just fine (and much better than a number of english only speakers around here).

 

Setting up a Celestron fork arm scope on a wedge is a bit complicated (well a bit more than just setting up a regular gem style mount). I would have a look in the NexStar forum, where there have been a few discussions on doing the initial setup and alignment on a wedge mounted NexStar controlled scope like your SE. Even if the setup and polar alignment is done with the NexStar firmware you'll find some polar alignment tips that will also apply to doing it with SharpCap.

 

When you are setting up your scope always remember that there are two different types of alignment. The initial alignment (sometimes called the goto alignment) which builds the sky model and loads the motor controllers in your mount (gets it all ready to be used). The initial aignment is always done through the hand controller (either the physical one, a software hand controller or in one of the scope control apps running on an external PC/tablet/phone). When you are wedge mounted in the physical hand controller this is called the EQ North/South alignment. Polar alignment is a second step and is a physical process where the mount/wedge etc. is moved to bring the scope into polar alignment. While it is possible with some setups to do a polar alignment first using a polar alignment scope, most of the time the initial alignment must be done first. Polar alignment can be peformed with a variety of aids, there is a polar alignment routine in the hand controller, or via SharpCap, or an add on product called PoleMaster, or via drift alignment routines. The choice is yours.

 

A couple of things to watch for  ...

 

1) most people have given up on using a wedge for imaging and went to a different mount (like an AVX or similar gem style or staying in alt az mode and using very short exposures) and because of that there isn't a lot of experience and discussion about setting up a wedge and polar aligning it. Some of the information is quite old and you need to notice that there has been recent (within the past year or so) firmware changes that can help. You will notice that much of the discussion is around using the Evolution mount on a wedge ... don't worry about this as the hand controller firmware on the Evolution is exactly the same as on the SE mounts (the Evo's just have a few other features that the SEs don't).

 

2) Most people have given up on using the smaller SE mount (the one for the 4 and 5" SE scopes) with the built in altitude adjuster (the rod), so you may see a few posts with comments like "don't bother doing this". However, using one of these mounts with an actual wedge is just like the setup on the larger SEs (the 6 and 8" versions) and the Evolution and CPC mounts, it's only the wedge that gets bigger on the bigger scopes, the firmware controlling it all is all the same.


Edited by mclewis1, 18 August 2019 - 08:40 AM.

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#4 Luis franco

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Posted 18 August 2019 - 09:19 AM

Luis,

 

Welcome to CN. Your english in your post is just fine (and much better than a number of english only speakers around here).

 

Setting up a Celestron fork arm scope on a wedge is a bit complicated (well a bit more than just setting up a regular gem style mount). I would have a look in the NexStar forum, where there have been a few discussions on doing the initial setup and alignment on a wedge mounted NexStar controlled scope like your SE. Even if the setup and polar alignment is done with the NexStar firmware you'll find some polar alignment tips that will also apply to doing it with SharpCap.

 

When you are setting up your scope always remember that there are two different types of alignment. The initial alignment (sometimes called the goto alignment) which builds the sky model and loads the motor controllers in your mount (gets it all ready to be used). The initial aignment is always done through the hand controller (either the physical one, a software hand controller or in one of the scope control apps running on an external PC/tablet/phone). When you are wedge mounted in the physical hand controller this is called the EQ North/South alignment. Polar alignment is a second step and is a physical process where the mount/wedge etc. is moved to bring the scope into polar alignment. While it is possible with some setups to do a polar alignment first using a polar alignment scope, most of the time the initial alignment must be done first. Polar alignment can be peformed with a variety of aids, there is a polar alignment routine in the hand controller, or via SharpCap, or an add on product called PoleMaster, or via drift alignment routines. The choice is yours.

 

A couple of things to watch for  ...

 

1) most people have given up on using a wedge for imaging and went to a different mount (like an AVX or similar gem style or staying in alt az mode and using very short exposures) and because of that there isn't a lot of experience and discussion about setting up a wedge and polar aligning it. Some of the information is quite old and you need to notice that there has been recent (within the past year or so) firmware changes that can help. You will notice that much of the discussion is around using the Evolution mount on a wedge ... don't worry about this as the hand controller firmware on the Evolution is exactly the same as on the SE mounts (the Evo's just have a few other features that the SEs don't).

 

2) Most people have given up on using the smaller SE mount (the one for the 4 and 5" SE scopes) with the built in altitude adjuster (the rod), so you may see a few posts with comments like "don't bother doing this". However, using one of these mounts with an actual wedge is just like the setup on the larger SEs (the 6 and 8" versions) and the Evolution and CPC mounts, it's only the wedge that gets bigger on the bigger scopes, the firmware controlling it all is all the same.

Thank you for your reply, i use this video to get started, i hope this is the right tutorial for me.https://www.youtube....h?v=z3jlpqKfbNE



#5 Luis franco

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Posted 18 August 2019 - 09:25 AM

What I do is to get the scope to its zero position (pointing toward the north celestial pole) and then rotate the RA axis until it is approximately 90° east or west. You can start by getting Polaris in your camera field of view...that's close enough. Rotate 90° east or west. On a wedge this would be the Azimuth movement. Then start SC polar align. It makes a plate solve then says rotate the scope 90°.

 

I then return the scope to the 'zero position', and SC plate solves again and reads out the PA error. With no 'zero position' on an SE5, you would need to closely estimate the return to the  NCP. Then adjust the scope watching the readout error. If the error gets larger, go the other way. You can do the same with a wedge mounted SE5.

 

Hope this helps.

Thank you for your reply, so let me try to understand, when using my telescope with the wedge and when Sharpcap says to rotate the ra axis 90 degrees i have to move the legs of the mount right or left?



#6 spereira

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Posted 18 August 2019 - 10:45 AM

Thank you for your reply, so let me try to understand, when using my telescope with the wedge and when Sharpcap says to rotate the ra axis 90 degrees i have to move the legs of the mount right or left?

When using your mount with a wedge, I believe that you are first trying to get the fork arm to be pointing at Polaris.  Then when the instructions say to move the RA axis, in your case you need to rotate the scope on the azimuth axis, to get the scope pointing straight up to the Zenith (while keeping the fork arm pointing at Polaris).

 

Then, go on from there.

 

smp



#7 mclewis1

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Posted 18 August 2019 - 01:05 PM

Thank you for your reply, i use this video to get started, i hope this is the right tutorial for me.https://www.youtube....h?v=z3jlpqKfbNE

Luis,

 

That totorial will get you started. It is a relatively rough polar alignment, useful for getting close but you'll find that you'll need to use other methods (like SharpCap's polar alignment feature) to get accurate enough to start to use your C5 telescope for imaging. Having a real wedge is obviously going to help you make the fine adjustments required to get a good polar alignment (so you do not get star drifting due to the relatively long focal length of your telescope which is really sensitive to an accurate polar alignment). As you can imagine picking the whole mount up and moving it even small amounts isn't going to get you the accuracy needed. 

 

 

Start by getting that rough polar alignment done, then do an initial alignment (EQ North, two star alignment) and then check your goto accuracy by pointing to some well known object, this will prove that your setup is done correctly. Then use whatever polar alignment routine you want (hand controller, SharpCap, PHD Guide, PoleMaster, or a drift alignment) to fine tune your polar alignment. If you have not had to move the wedge very much during the polar alignment you are finished but most people find that it makes sense to do another two star alignment to make your goto accuracy as good as possible. This is helpful when you are imaging things that are too faint to see through the eyepiece so you can't easily verify your imaging subject is well centered.

 

All this is why most people just align the mount in Alt Az mode and do visual work or restrict their imaging to relatively short exposures using shorter focal length telescopes or camera lenses. Trying to do any longer exposure imaging with a C5 telescope (even with a focal reducer) on the smaller SE mount can be a frustrating excercise (because of the poor accuracy of the polar alignment and lot of play in the RA/Azimuth spur gears). Most people who want to do this type of imaging end up with a different mount.




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