HEQ5 Target alignment troubles

[bb453]

Hi everyone,

I have recently got myself a HEQ5, upgrading from the trusty Skywatcher Star Adventurer. I have only managed to get a couple of evenings of clear skies thanks to the great British weather but I'm having an issue with getting my telescope to align with the target that I am try to shoot. I perform the normal polar alignment and then do a two start alignment, using the hand controller to center the star in the camera frame. I then select M31 from the catelog and the mount slews to M31 as you would expect. The issue is that it hasn't centered M31 in frame like I would expect it too and I'm a little puzzled as to why? I have attached an image that I took this evening and did a very quick process of for reference.

Have I messed up something in my setting up of the mount? Any help would be much appreciated!

Cheers.

[vlaiv]

That is normal, there are several things that will make your goto be less than perfect.

You really need to do test exposures to see if target is nicely framed (so called frame&focus exposures), or you need to do plate solving to have automated centering (that is advanced thing and requires use of computer to recognize star patterns and direct mount to correct location).

[Seelive]

Were both the alignment stars you used on the same side of the meridian as M31?

[AstroMuni]

9 hours ago, bb453 said:

I perform the normal polar alignment and then do a two start alignment, using the hand controller to center the star in the camera frame. I then select M31 from the catelog and the mount slews to M31 as you would expect. The issue is that it hasn't centered M31 in frame like I would expect it too and I'm a little puzzled as to why?

Reading this might help understand how the 2/3 star alignment creates a mount model. https://eq-mod.sourceforge.net/testimages/eqmod_3star.html

[bb453]

57 minutes ago, vlaiv said:

That is normal, there are several things that will make your goto be less than perfect.

You really need to do test exposures to see if target is nicely framed (so called frame&focus exposures), or you need to do plate solving to have automated centering (that is advanced thing and requires use of computer to recognize star patterns and direct mount to correct location).

I did try and move the framing using the hand controller but it wouldn't move, I'll have another read of the manual to see what I'm missing!

[bb453]

53 minutes ago, Seelive said:

Were both the alignment stars you used on the same side of the meridian as M31?

I do believe that they were, I will try either side of the meridian next time and see if that helps

[vlaiv]

52 minutes ago, bb453 said:

I did try and move the framing using the hand controller but it wouldn't move, I'll have another read of the manual to see what I'm missing!

When you slew the mount with hand controller - you can select slew speed in multiple of sidereal. I think that SW mount supports from x1 up to x800 for slewing (even less than x1 for guiding).

If your hand controller is set to this lowest speed - x1, then it will take quite a while for you to notice the move.

With this sampling rate it will only move few pixels every second, so it would take holding that button dozen or so seconds to be able to notice the difference in position on the screen.

[Rallemikken]

Little trick if you use a DSLR and can't platesolve (no computer): After the test exposure (10-15 sec, high ISO) look for a brigth star that sticks out. Put the ISO on the camera at max, and put it in live view. If the star is visible (or better; a pattern of stars), use the handcontroller to move it around in the frame. Take a new tast exposure, and adjust again if nesecarry. This works on my Canon cameras. The live view will be mostly noise, but if you can pick out one or more stars, this does the trick.

[Cosmic Geoff]

I have found that with the similar EQ5 Synscan that inaccurate GoTo is all too common.  If you want a more accurate GoTo, you need to select alignment stars on the same side of the sky as the object you want to observe, and with one of them not too far from it.  Or use platesolving.  I routinely find that platesolving corrects the aim by 0.3, 0.5 or 0.7 degrees.  

[AstroMuni]

@bb453 may I suggest that you do the 3 star alignment with an eyepiece and then attach the camera. That should make life a lot easier.

Great image of M31 btw! Is there a reason you dont use a computer to control the mount, camera?

 

[bb453]

1 hour ago, AstroMuni said:

@bb453 may I suggest that you do the 3 star alignment with an eyepiece and then attach the camera. That should make life a lot easier.

Great image of M31 btw! Is there a reason you dont use a computer to control the mount, camera?

 

This was my first night of using the SV503 and HEQ5 setup so I'm just learning how it all works really at the moment. Up until now I've just been using the Star Adventurer. 

Autoguiding/Plate solving is something I will look at setting up in the future for sure. I'm just taking it one step at a time

Thanks for the feedback on the shot, I was pretty happy with it for my first test 

[bb453]

2 hours ago, vlaiv said:

When you slew the mount with hand controller - you can select slew speed in multiple of sidereal. I think that SW mount supports from x1 up to x800 for slewing (even less than x1 for guiding).

If your hand controller is set to this lowest speed - x1, then it will take quite a while for you to notice the move.

With this sampling rate it will only move few pixels every second, so it would take holding that button dozen or so seconds to be able to notice the difference in position on the screen.

Ah okay that makes sense, when I try again, I'll change the slew rate and with the other suggestions in the thread it should help! 

 

[bb453]

1 hour ago, Cosmic Geoff said:

I have found that with the similar EQ5 Synscan that inaccurate GoTo is all too common.  If you want a more accurate GoTo, you need to select alignment stars on the same side of the sky as the object you want to observe, and with one of them not too far from it.  Or use platesolving.  I routinely find that platesolving corrects the aim by 0.3, 0.5 or 0.7 degrees.  

I'm going to look into plate solving for sure! 

[AstroMuni]

1 hour ago, bb453 said:

Autoguiding/Plate solving is something I will look at setting up in the future for sure. I'm just taking it one step at a time

Wise decision. Its good to know how the basics work before you take the leap. ....I have the HEQ5 pro as well and started down a similar route to you around 2 years ago. I prefer the warmth of my house 🙂 so embarked on controlling the mount and everything else via an RPi after a while. Good luck.

Edited November 14, 2022 by AstroMuni

[Seelive]

5 hours ago, bb453 said:

I do believe that they were, I will try either side of the meridian next time and see if that helps

I doubt it, only use stars on different sides of the meridian to the target if you do 3 star alignment. I've always found 2 star alignment on the same side of the meridan as the target works better than 3 star alignment involving a meridian flip. And as @cosmic Geoff stated above, try to choose 1 of the alignment stars (ideally the first) near to the target.