Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

alan potts

Align scope with Polar axis

Recommended Posts

I feel I have a problem here and I am not sure how it came about as a few weeks back things worked OK.

Tonight in a effort to sort things out I put the Canon back on with a reducer giving about a 2 degree field by something over 1,25 degree, so a fair field of view. Even though the mount is according to software about 1arc min from PA and even the polar scope tells me its in about the right place pointing is utterly terrible.

I tried to get polaris into the camera field of view and could not, this to me seems to suggest something is rather wrong, in this area the Pole stsr is easy enough to see and at o point could make it appear on the screen.

The question is how does one readjust an AZ EQ 6's scope puck or saddle or what ever its called, if indeed you can, or do you shim the scope.

I am so fed up that until I can at least get this right I am doing nothing with the new camera which at the moment I am not happy with anyway.

Alan

Share this post


Link to post
Share on other sites

Correct polar alignment doesn't mean that the system has any idea where the telescope is actually pointing, just where the polar axis is pointing.  And, in fact, even if you have perfect polar alignment and the telescope is pointing at the celestial pole, that still doesn't mean that slewing anywhere else will be accurate.

Perhaps it might help to have a look at AstroTortilla?  I believe it can work in conjunction with APT.  It should be able to grab a frame and then plate solve to find out exactly where the telescope is pointing.

James

Share this post


Link to post
Share on other sites

Hi Alan,

I could be going off at a tangent here, but if you are using APT and platesolving, have you adjusted the focal length of your scope in the APT settings to take into account the reducer as this will impact the FoV and accuracy. Your new F/L will be the actual F/L of your scope multiplied by the effect of the reducer say 0.8x. Mine is 710mm x 0.8 = 568mm. 

You then store the adjusted F/L in the Tools tab (in my case 568mm) At the bottom you will see an object calculator where you can select your camera type and populate your F/L then hit recalc.

Apologies if I’m wildly off the beaten track with this suggestion and its completely unrelated.

 

John

  • Like 1

Share this post


Link to post
Share on other sites
Just now, Hughsie said:

Apologies if I’m wildly off the beaten track with this suggestion and its completely unrelated.

Ooh, that's a good call though.  Easy thing to forget.

James

Share this post


Link to post
Share on other sites
1 minute ago, JamesF said:

Ooh, that's a good call though.  Easy thing to forget.

James

.... and was completely forgotten by me when I changed scopes! 😖

Share this post


Link to post
Share on other sites
9 minutes ago, Hughsie said:

.... and was completely forgotten by me when I changed scopes! 😖

Ah, one of those DAMHIKIJKOK [1] things...

James

[1] Don't Ask Me How I Know. I Just Know, OK?

Share this post


Link to post
Share on other sites

I don't understand this obsession with getting good star alignment and Plate Solving on a permanent imaging setup with good PA. 

Goto a star near your target, centre it with the handset, Synch, then GoTo your target. 

If you have time to image another target, just repeat the process. 

Why on earth are you worried about not being able to see Polaris? 

Forget it and get on with imaging !! 

Michael 

 

Edited by michael8554

Share this post


Link to post
Share on other sites

Ha! Point taken. 

With a Planetarium if you've unnecessarily complicated the setup with one........?  :

Look how Alan's setup has mushroomed and it hasn't improved his problems has it ! 

Michael 

Share this post


Link to post
Share on other sites
9 hours ago, Hughsie said:

Hi Alan,

I could be going off at a tangent here, but if you are using APT and platesolving, have you adjusted the focal length of your scope in the APT settings to take into account the reducer as this will impact the FoV and accuracy. Your new F/L will be the actual F/L of your scope multiplied by the effect of the reducer say 0.8x. Mine is 710mm x 0.8 = 568mm. 

You then store the adjusted F/L in the Tools tab (in my case 568mm) At the bottom you will see an object calculator where you can select your camera type and populate your F/L then hit recalc.

Apologies if I’m wildly off the beaten track with this suggestion and its completely unrelated.

 

John

I am using APT at the moment but not Plate Solving, though the software is on the laptop but not installed. I am going back to absolute basics and stripping the rig of the duel scope set-up and just have one. I really feel I set everything up square flat and good and tight but this has in my view caused the problems. It is ever since I turned the mounting plate 90degrees and put the APM duel bar on that the problem arose.

I will report back as we seem to be in a another spell of clear weather, shame this can't be done in the day.

Alan

Share this post


Link to post
Share on other sites
10 hours ago, JamesF said:

Correct polar alignment doesn't mean that the system has any idea where the telescope is actually pointing, just where the polar axis is pointing.  And, in fact, even if you have perfect polar alignment and the telescope is pointing at the celestial pole, that still doesn't mean that slewing anywhere else will be accurate.

Perhaps it might help to have a look at AstroTortilla?  I believe it can work in conjunction with APT.  It should be able to grab a frame and then plate solve to find out exactly where the telescope is pointing.

James

A kind suggestion James but I do not need another program to get confused over. People tell me that the scope needs to point toward the polar axis when PA is right for pointing to be accurate at the start of play, it makes sense to me.

Alan

Share this post


Link to post
Share on other sites
6 hours ago, michael8554 said:

I don't understand this obsession with getting good star alignment and Plate Solving on a permanent imaging setup with good PA. 

Goto a star near your target, centre it with the handset, Synch, then GoTo your target. 

If you have time to image another target, just repeat the process. 

Why on earth are you worried about not being able to see Polaris? 

Forget it and get on with imaging !! 

Michael 

 

Michael,

I am struggling badly and can not find anything when slewing, with this new camera (071) the other night I was not even sure I could see Saturn when I slewed. Now this is in conjunction with not having a clue how to use the 071. People talk about Platesolve but I don't want another program to confuse me even more.

The idea of lining everything up was I guess starting in the right place so at least the scope would slew to close to the object which it doesn't at all, I don't have a finder om the telescope to look through but have managed with the guide scope and then a quick 6-10 secs with the Canon, this has worked well. I do not use a handset as even with this I was getting bad results, I now use EQdir.  So I am stripping off all the newly bought gear and going back to where I was 3 weeks back, I was happy then, which I am far from now. Once and if I can get that to work I may try the 071again, if not I will sling it in the cupboard with other unwanted item, I don't believe in this return to the seller lark, it is not fair on them. I have 4 Canon bodies that I understand inside out I can always mod one of these for a better image over the 40D.

Alan

Share this post


Link to post
Share on other sites
12 minutes ago, alan potts said:

at least the scope would slew to close to the object which it doesn't at all

Hi Is the -computer/software- time set correctly and in sync?

Cheers and good luck. It's usually something really simple.

  • Like 1

Share this post


Link to post
Share on other sites
16 minutes ago, alacant said:

Hi Is the -computer/software- time set correctly and in sync?

Cheers and good luck. It's usually something really simple.

I am fairly sure it is, I have never touched it, but will check, as you say it will be something simple, me probably. Really fed up 5 nights down the drain.

Alan

Share this post


Link to post
Share on other sites

Sorry if I've misunderstood your problem but I quite often find when I first start to align the telescope/mount to an alignment star that I cannot see the star in the eyepiece or by camera.  Have you simply tried to eyeball how far out the pointing is? Look along the telescope tube or through the finder  scope. If it's only just off I'd adjust the mount using the manual adjust in the planetarium application until the star comes into view, centre up and then sync to the star.  If it's way off I suggest checking you've input the right latitude and longitude and time. Have you remembered we're in daylight saving?  I made both mistakes only recently when setting up new planetarium software. 

  • Like 1

Share this post


Link to post
Share on other sites
41 minutes ago, Ouroboros said:

Sorry if I've misunderstood your problem but I quite often find when I first start to align the telescope/mount to an alignment star that I cannot see the star in the eyepiece or by camera.  Have you simply tried to eyeball how far out the pointing is? Look along the telescope tube or through the finder  scope. If it's only just off I'd adjust the mount using the manual adjust in the planetarium application until the star comes into view, centre up and then sync to the star.  If it's way off I suggest checking you've input the right latitude and longitude and time. Have you remembered we're in daylight saving?  I made both mistakes only recently when setting up new planetarium software. 

I feel I have all these covered and am aware from years of visual work that it can be some way off at first, but it shouldn't be as far out as it is with the EQdir system I am using with very good PA (1arc min)

Alan

Share this post


Link to post
Share on other sites
56 minutes ago, newbie alert said:

Think technology has made people forget the basics... PA and star alignment really isn't all that difficult..

I tend to agree to a point, my PA is good, 1 arc Minute, confirmed with the polar scope, assuming that is correct on the AZ EQ6, so lets assume that OK. A few weeks back when I slewed to anything it place the Object/Star in the field, sometimes even in the middle. I am fully aware how to star align with or without hand set, it is just now for what ever reason, it's a long way out. when you slew to Saturn and it ends up close to Jupiter the wheels have come off somewhere.

Alan

Share this post


Link to post
Share on other sites

One approach is to accept that some problems are inexplicable, so find a workaround instead.

With my permanent setup, the first Goto to a known star after switching on puts the star in the centre of the finder about 50% of the time, the rest it's somewhere in the FOV. 

Alan's error may be larger, the reasons for the error could be many, and become irrelevant once you've centred the star and Synched. 

Centreing in the finder puts the star in the DSLR viewfinder FOV. 

Then centre in the DSLR and Sync. 

The imaging scope is now accurately polar aligned AND star aligned with an area of the sky that includes your target. 

That's it, never mind if your scope is possibly twisted 10 degrees on the mount, it's pointing correctly and you're good to go. 

That's with a DSLR, I imagine getting the star visable on a small chip camera to be more  challenging. 

I certainly couldn't manage without a finderscope Alan, and it sounds like your other ways to find objects are frustrating you. 

Michael 

 

  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, michael8554 said:

One approach is to accept that some problems are inexplicable, so find a workaround instead.

With my permanent setup, the first Goto to a known star after switching on puts the star in the centre of the finder about 50% of the time, the rest it's somewhere in the FOV. 

Alan's error may be larger, the reasons for the error could be many, and become irrelevant once you've centred the star and Synched. 

Centreing in the finder puts the star in the DSLR viewfinder FOV. 

Then centre in the DSLR and Sync. 

The imaging scope is now accurately polar aligned AND star aligned with an area of the sky that includes your target. 

That's it, never mind if your scope is possibly twisted 10 degrees on the mount, it's pointing correctly and you're good to go. 

That's with a DSLR, I imagine getting the star visable on a small chip camera to be more  challenging. 

I certainly couldn't manage without a finderscope Alan, and it sounds like your other ways to find objects are frustrating you. 

Michael 

 

Basically what you outline here is what I have done for a good while now. I have bolted a finder scope to the side of the rig and taken the duel scope arrangement off, and put the Canon back on.

Right this was last night after I attempted to point the scope somewhere near Polaris, and I was careful not to ruin PA

Slewed to Dubhe, not far I would say, it didn't find it, I found it, centred it accurately and synced

 Slewed back to polaris, not even in the FOV.

After this gave up with a idea of going back to how it was and again checking every setting.

Lets see what happens tonight, I know the AZ EQ6 is not a 10 micron mount or similar but it was giving, pleasing to me results and now isn't.

Thanks for the replies,

Alan

Share this post


Link to post
Share on other sites

Hi Alan

Another thought(s).. which I may already have said and which you probably have done...  Try clearing down all the previous EQMOD alignment points before starting alignment and make sure that they aren't being saved on park or loaded on unpark.  When I was using EQMOD I  didn't save alignment points and did a fresh alignment on a nearby star (same side of meridian as target) then slewed to the target.  Another thing to do would be to try with the Synscan handset.

Dave

Share this post


Link to post
Share on other sites

Hi Alan,

Many years ago I had problems with an EQ6 with EQMOD.  This was my solution:

  1. Slew to anything.  Slew back to Polaris.
  2. Switch off the mount, disconnect / shut down the planetarium program.
  3. Undo the clutches and physically put the scope back to the home position - just eyeball it.
  4. Switch back on, reconnect etc and try again.

Mike

  • Like 1

Share this post


Link to post
Share on other sites

Nearly there Alan. 

Synch on Dubhe if it's near your target, don't go back to Polaris to see if it's there. 

It wasn't, so what, who cares, why does it matter so much to you ?

Targets near Dubhe will be in your DSLR FOV when you try a goto. 

Get on with imaging  !!!! 

Michael 

  • Like 1

Share this post


Link to post
Share on other sites
4 hours ago, alan potts said:

tend to agree to a point, my PA is good, 1 arc Minute, confirmed with the polar scope,

How do you confirm with a polar scope, if you can see it's out then surely you can correct it?

Polar scope method is classed as a rough polar alignment

Are you on a fixed mount or a setup and tear down?

Polar alignment and star alignment are different kettles of fish..if pointing is out then redo your star alignment but don't do as someone else does and redo the polar alignment and wonder why the star alignment is out so re entering with the clutches off!!

Apologies if I come across as brash..not intended..

 

Share this post


Link to post
Share on other sites
2 hours ago, Laurin Dave said:

Hi Alan

Another thought(s).. which I may already have said and which you probably have done...  Try clearing down all the previous EQMOD alignment points before starting alignment and make sure that they aren't being saved on park or loaded on unpark.  When I was using EQMOD I  didn't save alignment points and did a fresh alignment on a nearby star (same side of meridian as target) then slewed to the target.  Another thing to do would be to try with the Synscan handset.

Dave

Already done that, next I'm trying standing in a bucket. Don't want to go back to the handset, that was rubbish most of the time but I probably didn't have good PA then as it was not fixed in the observatory.

Alan

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.