HEQ5 Pro - Guiding with 11Kg payload? - Forums

Topic starter

Apr 23, 2022 · Edited: Apr 23, 2022

Just looking for advice on what can be achieved on an HEQ5 Pro (belt modded) from a guiding point of view with an 8" Newt, camera, filter wheel etc.

I'm getting 0.6 arc secs regularly now with an 11Kg payload in a suburban location. I'm not sure this mount will do any better, although I do see spells around the 0.4 arc secs.

Please let me know if you get better and how ... otherwise I will be looking at upgrading my mount; I'm not unhappy with it, however my stars do have a VERY slight eccentricity which drives me mad.

Ryan Jones

Apr 24, 2022

Hi Andy,

I’m carrying about the same weight on my HEQ5 Pro. I mostly guide at 0.4-0.5. There’s nothing wrong with guiding at 0.6 though. I can understand you wanting to get rid of your eccentricity issues though. From the graph you’ve posted you can see several large declination pulses. I would suggest this maybe due to a bit of backlash in your declination axis. You can tune this out quite easily. Instructions on how can be found on the internet. Hope this helps

Ryan

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@acrux_astrofotografia

Apr 24, 2022

Hi mate, interesting discussion … I have the HEQ5 pro belt modified (did the upgrade myself). I have been getting good results with a Newtonian 150PDS onboard plus a mono QHY163M plus filter wheel and a 60mm guide scope plus onboard mini pc (I think I have about 9.5kgs onboard as I sometimes add my camera as a piggyback)
my take, I get good results however it can be very sensitive. I mean, balance plays an important role and it will be temperamental some days I suddenly get great guidance and some other days not the best, I guess seeing alado plays a role . I have found that with my focal Length this has been ok. The strange thing is that that I have a small wide field refractor at around 6.5kgs and get similar guiding results, one would think that you would get better results due to the lower weight, and this has not been the case I would believe that it would be within the limits of what the mount can do. I can manage for now, if I wanted to go deeper/longer focal length probably need to upgrade. One thing to consider is that as soon as you upgrade you will likely get a much heavier mount… see photo attached my last photo session, this is M83 that I was capturing last night via Nina with the Newtonian at 750mm, there you will see the guiding graph below. When I do the brains 🧠 on phd it always gives me suggestions and I act on them. For now, As long as my images look good I don’t worry too much… about the graph😜 hope this helps

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Christopher Davenport

Apr 24, 2022

My iOptron mount is capable of 0.25 with an encoder.

The best i can get my rig RMS is 0.6 with my current guidescope, but being lazy i accept avg of around 1 as good enough as it does not affect my images at a focal length of 564mm.

The focal length of a guide scope makes a difference, a OAG is needed when you go deep. Suggest you try this before a upgrade of the mount.

Andy Wray

Topic starter

Apr 24, 2022

Christopher Davenport:
The focal length of a guide scope makes a difference, a OAG is needed when you go deep. Suggest you try this before a upgrade of the mount.

I should have said: I did recently move from a separate guidescope to an OAG and that reduced my guiding from about 1.2 arc secs to 0.6 with the OAG. As you say, 0.6 arc secs is probably fine for my focal length (912mm), however I can see that I still have some DEC backlash/guiding issues which I need to understand and iron out.

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Dale Penkala

Apr 24, 2022 · Edited: Apr 24, 2022

As mentioned there are a lot of different things that play a role in your guiding. A couple years ago I come across an article by AP on balance. At 1st I didn’t think much of this way of balancing but when I did it this way I need a .2 difference in my guiding and this was before I got my AP1200 mount to btw.
Maybe you are doing it this way now, balance-to-optimize-guiding.pdf but just thought I’d share it with you in this thread in case you or others want to give it a try. Like I said, it did make a sublet difference but I’ll take any advantage I can get.

Dale

D. Jung

Apr 24, 2022

I'm happy if i get under 1 arc sec with 9kg on my trusty AVX…

Andy Wray

Topic starter

Apr 24, 2022

Dale Penkala:
Maybe you are doing it this way now, balance-to-optimize-guiding.pdf but just thought I’d share it with you in this thread in case you or others want to give it a try. Like I said, it did make a sublet difference but I’ll take any advantage I can get.

Definitely food for thought

Ryan Jones

Apr 24, 2022

Another change I made to help with moment of inertia ( as referenced in the link above ) is to rotate the OTA to point the focuser down. It moves the weight of the focuser, camera, Coma corrector etc down closer to the RA axis. As a consequence the counterbalance weight below the axis can also be brought closer the the RA axis. It’s a win win situation. The only down side is that it then makes it very difficult to use visually.

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Dale Penkala

Apr 24, 2022

Ryan Jones:

Another change I made to help with moment of inertia ( as referenced in the link above ) is to rotate the OTA to point the focuser down. It moves the weight of the focuser, camera, Coma corrector etc down closer to the RA axis. As a consequence the counterbalance weight below the axis can also be brought closer the the RA axis. It’s a win win situation. The only down side is that it then makes it very difficult to use visually.

This is the exact same way I mount all my newts. Add in the balancing technique and I’d have to say it would make some sort of change. Thats if @Andy Wray made changes. He may already be orientated that way???

Dale

Andy Wray

Topic starter

Apr 24, 2022

Ryan Jones:

Another change I made to help with moment of inertia ( as referenced in the link above ) is to rotate the OTA to point the focuser down. It moves the weight of the focuser, camera, Coma corrector etc down closer to the RA axis. As a consequence the counterbalance weight below the axis can also be brought closer the the RA axis. It’s a win win situation. The only down side is that it then makes it very difficult to use visually.

Why on earth didn't I think of that? I'm exactly 180 degrees away from that!! I'll be doing that next time as I don't do visual anymore.

andrea tasselli

Frequent contributor

Apr 24, 2022

There are 2 moments of inertia, one about the Dec axis and one about the RA axis. The only one that is affected by the change is the RA-relative moment of inertia, the Dec one isn't. The RA axis doesn't actually experience reversal so the effect isn't as big as if it were to reverse direction such as is the case for the Dec axis. Furthermore, the bigger the scope the less this change affects dynamic response as less of the total mass is taken up by the focuser and imaging gear (which is substantially independent from the size of the scope). Thus, small scopes (e.g. a 6" short newton) are more advantaged by the change than say an 8" and even less so for bigger ones. In my case I can't see any advantage with my 6" f/4 newt (5.3 kgs net weight against around 1 kg of imaging gear) although there might be for some nor did I test extensively in both configurations. For my 12" newt (19 kgs of net scope weight, mounted) the difference isn't worth the bother.

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Stuart Taylor

Apr 24, 2022

Andy Wray:
Just looking for advice on what can be achieved on an HEQ5 Pro (belt modded) from a guiding point of view with an 8" Newt, camera, filter wheel etc.

I'm getting 0.6 arc secs regularly now with an 11Kg payload in a suburban location. I'm not sure this mount will do any better, although I do see spells around the 0.4 arc secs.

Please let me know if you get better and how ... otherwise I will be looking at upgrading my mount; I'm not unhappy with it, however my stars do have a VERY slight eccentricity which drives me mad.

This looks pretty impressive! I only have a slightly bigger payload on my EQ6R Pro and get about the same guiding! Well done!

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Ian Dixon

Apr 25, 2022

Stuart Taylor:
Andy Wray:
Just looking for advice on what can be achieved on an HEQ5 Pro (belt modded) from a guiding point of view with an 8" Newt, camera, filter wheel etc.

I'm getting 0.6 arc secs regularly now with an 11Kg payload in a suburban location. I'm not sure this mount will do any better, although I do see spells around the 0.4 arc secs.

Please let me know if you get better and how ... otherwise I will be looking at upgrading my mount; I'm not unhappy with it, however my stars do have a VERY slight eccentricity which drives me mad.

This looks pretty impressive! I only have a slightly bigger payload on my EQ6R Pro and get about the same guiding! Well done!

I second that... I have seen folks with NEQ6 mounts average about .8 - 1.0 RMS with less weight.

andrea tasselli

Frequent contributor

Apr 25, 2022 · Edited: Apr 25, 2022

I'd careful drawing conclusions without knowing where the scope was pointing, how well balanced it was and what were the local conditions (wind, seeing, transparency). And PA too.

Christopher Davenport

Apr 25, 2022

Andy Wray:
Christopher Davenport:
The focal length of a guide scope makes a difference, a OAG is needed when you go deep. Suggest you try this before a upgrade of the mount.

I should have said: I did recently move from a separate guidescope to an OAG and that reduced my guiding from about 1.2 arc secs to 0.6 with the OAG. As you say, 0.6 arc secs is probably fine for my focal length (912mm), however I can see that I still have some DEC backlash/guiding issues which I need to understand and iron out.

Just another thought, which i remember from Steve Richards book, make every photon count. It really help not to be perfectly balanced on the DEC axis and even to be slightly polar misaligned on the DEC axis. This way all corrections in DEC are in the same direction. Over the years and based on others insight shared with me, it seems that being west side heavy is best. i.e the mount is always lifting the load. This way the load lies engaged on the teeth of the cog / belt and is pushing the load. On the opposite side it would be pulling it, which tends not to work as well, as the moment teeth change, the mount falls onto the next tooth.
This is all abit on the edge of my knowledge. (BTW this used to work really well with my HEQ5.) Now that i have a GEM45, it is far more precise, so I am not getting as much of a benefit off this, althought it might just be that i need to be more precise about things.)

Only issue with this is that after a meridian flip, you need to lighten the counter weights to make the scope side heavier.
I tend to set the weights for the side i will be doing most of my imaging.

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Patrick

Apr 25, 2022

Andy Wray:
Just looking for advice on what can be achieved on an HEQ5 Pro (belt modded) from a guiding point of view with an 8" Newt, camera, filter wheel etc.

I'm getting 0.6 arc secs regularly now with an 11Kg payload in a suburban location. I'm not sure this mount will do any better, although I do see spells around the 0.4 arc secs.

Please let me know if you get better and how ... otherwise I will be looking at upgrading my mount; I'm not unhappy with it, however my stars do have a VERY slight eccentricity which drives me mad.

If you have such consistent guiding perfomance on both axis, i wonder why you have elongated stars at all. Did check if the elongation is in north-south or east-west direction?

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