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HEQ5 over shooting park position.


Nebulosityireland

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Hi,

I have a HEQ5 with the Rowan belt mod.

From day 1 of using it I found after a good polar alignment, at the end of my shooting session when I choose return to the home position, it hugely over shoots home.

Any idea why this may be happening?

I also found guiding to fluctuate a lot.

I also have an NEQ6 which in comparison is night and day.

Equipment:

William Optics GT71

HEQ5

ASIAIR 

ASI120mm with guidescope mini

ASI2600MC 

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1 hour ago, scotty38 said:

I assume you power it on in the "Home" position and you don't manually move its axes at any time? I also assume plate solving etc works ok?

Yes I do a lot of imaging and would be very familiar. Started in home position. Have tested, go to home before polar alignment and still does the same. 

When I perform a PA and initially slew to target, it is not on target and has to correct a good bit, but after that everything is 100% accurate for switching targets, plate solving etc..

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First the HEQ5 has no home position sensor.

From the comments your manual home position & where the mount after PA & Alignment disagree.  Does it go to the the correct position if you do a goto home after both PA and other successful goto's?

When I had the HEQ5 I would PA, then do a goto, release clutches and centre my target. Then I'd do a goto home position which was more accurate than my rough manual home position.  Further goto's then were fine.

The mount, when star alignments are made will adjust for inaccuracies, some of which may be due to poor PA, bad location or time information.

If your start & end home position is out by the same amount I would double check your location, date/time and DST etc.

 

 

 

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36 minutes ago, StevieDvd said:

First the HEQ5 has no home position sensor.

From the comments your manual home position & where the mount after PA & Alignment disagree.  Does it go to the the correct position if you do a goto home after both PA and other successful goto's?

When I had the HEQ5 I would PA, then do a goto, release clutches and centre my target. Then I'd do a goto home position which was more accurate than my rough manual home position.  Further goto's then were fine.

The mount, when star alignments are made will adjust for inaccuracies, some of which may be due to poor PA, bad location or time information.

If your start & end home position is out by the same amount I would double check your location, date/time and DST etc.

 

 

 

Hi Stevie,

Surely once you get a tight PA touching the mount to release the clutches is a bad idea as it can move the PA?

Steps I've tested to recreate:

Turn everything on.

In the ASIAIR open the mount and go to home position (just to verify start point).

Perform a PA 

Slew to target (after a correction it gets there.)

Slew to any target and it works fine.

End of my session (I know its not required) return to home position. This is when it's seen.

 

Settings for location and DST are irrelevant since I'm using the ASIAIR.

I autoguide every time so I think that correct any inaccuracies but I'm wondering is that hiding the issue and explained why my guiding is glitchy?

 

As explained I have an NEQ6 and with the same setup it works perfectly. 

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I sometimes get a slightly incorrect home position after starting from home.  

Presumably you haven't manually moved the mount to find an alignment star after starting from home.  I know some people do this, but I never do.  

Only thing I put it down to is not being able to exactly balance my mount due to the finder guider position being to one side or angle of EFW making Dec slightly off balance.  

Carole 

  

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FYI. The clutches & mount moving won't affect PA as long as your mount is fastened to the tripod/pier and adjustment bolts are not loose. Some mounts even allow for clutch free movement as they have secondary encoders (not the HEQ5 though). It can affect star alignment data in the mount though, if not handled by secondary encoders.

The bit where you say "Slew to target (after a correction it gets there.) " could be the issue as I'm not 100% the Asiair will do a correction after a 'goto home' as it does in a normal goto.

If you were to save the home position as a custom target (I'd need to look up how to do that) and do a goto that, it may work correctly, whereas a plain park fails.

But the question is what is the AAP correcting and does it continue to adjust the correction for each subsequent goto. If it was an initial correction the guiding would likely be reasonable but, if it needs continous corrections for each goto, that would most likely upset the guiding process.

Platesolving & auto-centering could be hiding the real issue. If the first goto needs a 'good bit' of adjustment then I'd re-check the basics; date/time, location, clutches tight, mount connection not loose, scope balanced etc.

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18 hours ago, Nebulosityireland said:

Potentially, I didn't know one existed. Any way of testing this?

It was only a guess as never owned a Skywatcher mount but some have a sensor within the worm block as seen on dismantling videos...

How are you parking, within the handset or within  your capture software?

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3 hours ago, newbie alert said:

It was only a guess as never owned a Skywatcher mount but some have a sensor within the worm block as seen on dismantling videos...

How are you parking, within the handset or within  your capture software?

Parking from the ASIAIR. 

Once I achieve a PA I don't touch the mount, from there everything is automated.

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19 hours ago, carastro said:

I sometimes get a slightly incorrect home position after starting from home.  

Presumably you haven't manually moved the mount to find an alignment star after starting from home.  I know some people do this, but I never do.  

Only thing I put it down to is not being able to exactly balance my mount due to the finder guider position being to one side or angle of EFW making Dec slightly off balance.  

Carole 

  

Thanks Carole

Once I complete my PA I manage everything from the ASIAIR remotely so I assumed it would end up in the same position. You have me thinking though if it may be a gear ratio issue that it's step is slightly out or slipping. 

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18 hours ago, StevieDvd said:

FYI. The clutches & mount moving won't affect PA as long as your mount is fastened to the tripod/pier and adjustment bolts are not loose. Some mounts even allow for clutch free movement as they have secondary encoders (not the HEQ5 though). It can affect star alignment data in the mount though, if not handled by secondary encoders.

The bit where you say "Slew to target (after a correction it gets there.) " could be the issue as I'm not 100% the Asiair will do a correction after a 'goto home' as it does in a normal goto.

If you were to save the home position as a custom target (I'd need to look up how to do that) and do a goto that, it may work correctly, whereas a plain park fails.

But the question is what is the AAP correcting and does it continue to adjust the correction for each subsequent goto. If it was an initial correction the guiding would likely be reasonable but, if it needs continous corrections for each goto, that would most likely upset the guiding process.

Platesolving & auto-centering could be hiding the real issue. If the first goto needs a 'good bit' of adjustment then I'd re-check the basics; date/time, location, clutches tight, mount connection not loose, scope balanced etc.

Hi Stevie,

Yes that makes sense and although I know opening the clutches once PA and moving shouldn't cause an issue I was wondering if this was indicative of why my guiding isn't great. I get periodic spikes and I thought could there be a gear ratio issue or slippage causing the spike. Which in turn results in the park position also slipping and after hours of this is magnified when returning to park?

 

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@Nebulosityireland is this a new mount or new to you (sceond-hand)? And who did the Rowan mod & when?

It's possible that the belts are too loose or too tight. You could remove the cover and see - instructions for the upgrade are here should you wish to check them.

I would also:

  • Run the mount using the handset and rotate 360 degrees for both axis at a high speed rate to see if there are any slow/sticky points.
  • Tighten the clutches and check for any play in both axis.
  • Loosen the clutches and check for any binding, rotate by hand 360 both axis.

Anything with the above may help getting at the cause of the problem.

 

 

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On 14/12/2022 at 15:18, StevieDvd said:

@Nebulosityireland is this a new mount or new to you (sceond-hand)? And who did the Rowan mod & when?

It's possible that the belts are too loose or too tight. You could remove the cover and see - instructions for the upgrade are here should you wish to check them.

I would also:

  • Run the mount using the handset and rotate 360 degrees for both axis at a high speed rate to see if there are any slow/sticky points.
  • Tighten the clutches and check for any play in both axis.
  • Loosen the clutches and check for any binding, rotate by hand 360 both axis.

Anything with the above may help getting at the cause of the problem.

 

 

Hi Stevie,

I bought from new from FLO.

It was bought with the mod included.

Thanks for the tips, will test rotations etc..

There doesn't appear to be any binding.

Thanks,

Aaron

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9 hours ago, Nebulosityireland said:

Hi Stevie,

I bought from new from FLO.

It was bought with the mod included.

Thanks for the tips, will test rotations etc..

There doesn't appear to be any binding.

Thanks,

Aaron

You bought from FLO, that's good news. They are very good at post sales support and one of the best astro dealers as other forum members can attest to.

Steve

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