Help. Star trails on HEQ5 Pro with 10 sec exposures anywhere other than polar home position.

[Ross1204]

So last night I set up my scope using the following steps - 

1) Level Tripod
2) Rough polar alignment via polar scope (HEQ5 Pro)
3) Attach counter weight and OTA
4) Balance setup 
5) Set in home position 
6) Use polar align feature in sharpcap to more precisely polar align 
7) Take photo on dslr to gauge focus
8) Re-focus to make stars pin point

I then took a 10 second exposure in the home position and the stars looked pinpoint. The problem arises though when I manually change the scopes orientation to anywhere other than the home position I start to get star trails on exposures ranging from 4-10+ seconds.

I've never had this issue before and have been able to plate solve fine in APT the past few times I've set up. I also believe the balance to be good as I can push the scope with a finger and comes to a smooth stop in any orientation.

Any help is much appreciated.

Ross
 

[knobby]

I'm a Celestron man but is it actually tracking ? On my AVX it doesn't start tracking til an alignment has been made and you only mentioned polar alignment ? 

All the best and good luck.

[Ross1204]

29 minutes ago, knobby said:

I'm a Celestron man but is it actually tracking ? On my AVX it doesn't start tracking til an alignment has been made and you only mentioned polar alignment ? 

All the best and good luck.

Thanks for the reply.

It was hard to tell if it was tracking as the star trails were bad but I'm running off the theory that I should not see any star trails for anything under a 30 second exposure? 

I also don't bother with any star alignment as the plate solving will get me where I wanna go and frame the object in the center fov.

I also manually positioned the scope pretty much pointing directly up and took a 10sec sub which revealed star trails, I then placed the scope cap on and positioned my phone facing up and took a 10sec sub and no star trails.

I hope its something simple to fix as the whole setup has been working fine, it would happily take an image in the home position solve it and slew to a target take another image with no star trails and solve that. All very strange.

Ross

[spillage]

Do you use PHD to track?

[cuivenion]

Do you have the tracking rate set to sidereal?

[Ross1204]

13 minutes ago, spillage said:

Do you use PHD to track?

Yes. However I did not load/set up PHD2 at this point I just had the HEQ5 Pro, OTA, Counter weight positioned and polar aligned via sharpcap. The two images were taken via the DSLR directly, the image at the polar home no star trails and any image elsewhere star trails.

Ross

6 minutes ago, cuivenion said:

Do you have the tracking rate set to sidereal?

Is this a default setting? I honestly don't think I've changed anything myself unless PHD2 or APT tool has for me?

As mentioned above though I was getting this without the mount being connected to the laptop and manually positioning the scopes orientation.

Ross

[spillage]

Next time run sharpcap then once PA has been done leave the scope in the second position then re-run sharpcap and use the second postion as the first and the home position as the last to check for errors.

I would also be tempted to run drift align in phd2.

Having your PA out a bit is not to much of a bad thing if your guiding.

[Ross1204]

17 minutes ago, spillage said:

Next time run sharpcap then once PA has been done leave the scope in the second position then re-run sharpcap and use the second postion as the first and the home position as the last to check for errors.

I would also be tempted to run drift align in phd2.

Having your PA out a bit is not to much of a bad thing if your guiding.

I got to believe that the polar alignment was OK because when I started the tool within sharpcap my polar align error from my rough polar alignment via the polar scope was 4mins, I then dialed that down to 30 seconds and thought that will be good enough.

Surely that't good enough for a 10sec sub with no star trails?

Ross

[cuivenion]

54 minutes ago, Ross1204 said:

Yes. However I did not load/set up PHD2 at this point I just had the HEQ5 Pro, OTA, Counter weight positioned and polar aligned via sharpcap. The two images were taken via the DSLR directly, the image at the polar home no star trails and any image elsewhere star trails.

Ross

Is this a default setting? I honestly don't think I've changed anything myself unless PHD2 or APT tool has for me?

As mentioned above though I was getting this without the mount being connected to the laptop and manually positioning the scopes orientation.

Ross

There's a lot less rotation movement at the pole, so it makes sense that you wouldn't have star trails when imaging there. If you're not connected to the laptop or a handset then surely the HEQ5 wouldn't track at all, unless I'm missing something.

[spillage]

It may be your guide scope flexing, I would check all your bolts and screws are tight especially if you strip down every session. I may even be a balance issue with you scope.

If you are putting your kit together every time then you can introduce lots of issues regarding guiding, PA, balance, cable snags.

Even with good PA I still would be running PHD regardless of my exposure times. I feel this is like turning of the traction control on your car, if its there to help use it.

[cuivenion]

Do you use EQMOD or a handset to control the mount?

[newbie alert]

When using sharpcap I'm looking for the best PA i can get..with both figures under 5..if going to the trouble of using sharpcap then a extra couple of minutes getting as good as the seeing will allow is surely worth it.. try getting the most precise PA you can next time and see if it makes a difference,but drift on a 10-30 sec exposure don't sound right to me

[cuivenion]

It sounds to me like the mount isn't tracking at all. I think it's possible that the op forgot to initiate the tracking on this occasion. In EQMOD you have to start tracking after you unpark the mount, it doesn't start tracking by default. I can't comment on the handset, I've always used EQMOD.

[cfpendock]

If you can see star trails on a 4 second exposure, then either you didn't polar align on polaris, or the RA drive on the mount isn't working properly.

Chris

[Ross1204]

1 hour ago, cuivenion said:

Do you use EQMOD or a handset to control the mount?

I use EQMOD but this was happening when not connected to the laptop at all just the mount, scope and camera.

 

1 hour ago, newbie alert said:

When using sharpcap I'm looking for the best PA i can get..with both figures under 5..if going to the trouble of using sharpcap then a extra couple of minutes getting as good as the seeing will allow is surely worth it.. try getting the most precise PA you can next time and see if it makes a difference,but drift on a 10-30 sec exposure don't sound right to me

I really don't think its polar alignment as it was dialed in at sub 40 secs of error before taking the exposures. I my opinion if I had used the original rough polar alignment via the scope that was 4mins of error this shouldn't have giving me star trails for a 10sec exposure.

1 hour ago, cuivenion said:

It sounds to me like the mount isn't tracking at all. I think it's possible that the op forgot to initiate the tracking on this occasion. In EQMOD you have to start tracking after you unpark the mount, it doesn't start tracking by default. I can't comment on the handset, I've always used EQMOD.

You are correct in that the mount wasn't tracking as it was not connected to the laptop. I was just manually positioning the mount to different areas to see what gave me star trails and anything other than the home position produced star trails.

1 hour ago, cfpendock said:

If you can see star trails on a 4 second exposure, then either you didn't polar align on polaris, or the RA drive on the mount isn't working properly.

Chris

I moved the brightest star in the FOV of the polar scope to the correct polar hour position and when checked in Sharpcap it must of been the correct star to give me an already stated 'Good' alignment? Like I have previously stated the mount was not connected so there was no tracking going on.

I'm just confused as to why I am getting star trails from every other position other than the home position. I'm just manually moving the scope and locking clutches in a different position and with a polar alignment error of 30 seconds a 10sec image should be no problem right?

[cfpendock]

7 minutes ago, Ross1204 said:

I'm just manually moving the scope and locking clutches in a different position and with a polar alignment error of 30 seconds a 10sec image should be no problem

It shouldn't be any problem provided the mount is switched on and tracking.  If the mount is not tracking then you will have star trails, the length of which will depend on how far from Polaris you are imaging, and irrespective of whether you are polar aligned or not.  The Earth rotates at around 15 degrees per hour, and that is what your mount must track at in order to avoid trails.

Chris

[Ross1204]

2 minutes ago, cfpendock said:

It shouldn't be any problem provided the mount is switched on and tracking.  If the mount is not tracking then you will have star trails, the length of which will depend on how far from Polaris you are imaging, and irrespective of whether you are polar aligned or not.  The Earth rotates at around 15 degrees per hour, and that is what your mount must track at in order to avoid trails.

Chris

Ok, so how does that relate to the fact I had no star trails on my phone camera with the same exposure length when facing it up on my telescope end cover? Could it be the increased focal length of the scope compared to the camera which in turn enhances the movement hence the trails?

Ross

[tooth_dr]

48 minutes ago, Ross1204 said:

I use EQMOD but this was happening when not connected to the laptop at all just the mount, scope and camera.

 

I really don't think its polar alignment as it was dialed in at sub 40 secs of error before taking the exposures. I my opinion if I had used the original rough polar alignment via the scope that was 4mins of error this shouldn't have giving me star trails for a 10sec exposure.

You are correct in that the mount wasn't tracking as it was not connected to the laptop. I was just manually positioning the mount to different areas to see what gave me star trails and anything other than the home position produced star trails.

I moved the brightest star in the FOV of the polar scope to the correct polar hour position and when checked in Sharpcap it must of been the correct star to give me an already stated 'Good' alignment? Like I have previously stated the mount was not connected so there was no tracking going on.

I'm just confused as to why I am getting star trails from every other position other than the home position. I'm just manually moving the scope and locking clutches in a different position and with a polar alignment error of 30 seconds a 10sec image should be no problem right?

All stars rotate appear to rotate around polaris, so the further you move from polaris the longer the star trails will be.  How would you not be getting star trails if your mount isnt tracking?

[Ross1204]

9 minutes ago, tooth_dr said:

All stars rotate appear to rotate around polaris, so the further you move from polaris the longer the star trails will be.  How would you not be getting star trails if your mount isnt tracking?

I guess I am working off the principle that to shot the milky way anything under 30secs wont produce star trails. So is there a difference when the scope is positioned and the clutches locked to take image as opposed to mounting the dslr on a tripod to take a shot?

Ross

[tooth_dr]

9 minutes ago, Ross1204 said:

I guess I am working off the principle that to shot the milky way anything under 30secs wont produce star trails. So is there a difference when the scope is positioned and the clutches locked to take image as opposed to mounting the dslr on a tripod to take a shot?

Ross

 

There is no difference, as both tripods/mounts are fixed in position.  If you are shooting a widefield image with a short focal length lens eg 18mm then you will get away with 30s without noticeable trailing.  If you are using a telescope at say 600mm focal length then even one second will show trailing.  As an average you can divide 500 by the focal length of your lens/telescope, to give you the number of seconds you can expose with the trailing not being noticeable.

 

[knobby]

18 minutes ago, tooth_dr said:

 

There is no difference, as both tripods/mounts are fixed in position.  If you are shooting a widefield image with a short focal length lens eg 18mm then you will get away with 30s without noticeable trailing.  If you are using a telescope at say 600mm focal length then even one second will show trailing.  As an average you can divide 500 by the focal length of your lens/telescope, to give you the number of seconds you can expose with the trailing not being noticeable.

 

And 1.5 x focal length if not full frame.

[cfpendock]

1 hour ago, Ross1204 said:

Could it be the increased focal length of the scope compared to the camera which in turn enhances the movement hence the trails?

Yes, as others above have indicated, I think that must be the reason.

Chris

[dph1nm]

I have this feeling that with the V4 handset until you do a star alignment it does not track (unless you switch it on manually from the setup menu).

NigelM

[Neil K Sharpe]

I had this problem with my HEq5 first time I had not locked up the scope, so it was not attached to the motor. The second time I hade fitted a GO-TO, it turned out it does not track unless you first set it up with Two stars or more. I don't know if any of this helps.

Neil