Help Please? Guiding gets worse as night progresses

[Jkulin]

Hi All,

I'm getting quite frustrated as when I start a new session everything is reasonable, not perfect but reasonable and as the night progresses the guiding gets worse.

This is the start this evening: -

And it has now progressed to this: -

The same happened the other night with M82: -

And then progressed to this: -

The scope is perfectly balanced, there is no slippage anywhere, I've uploaded the PHD2 log files from the M82 night and this evenings.

I'm getting so frustrated, the seeing seems fine as well.

I'm using a Skywatcher mount which locks everything up nicely as well.

Any help please?

Thanks.

 

Edit sorry I uploaded the debug logs and not the guide logs, so have attached them, the latest guide log says "Star Lost" but there wasn't a cloud anywhere to be seen and I was watching the screen and it all appeared perfect, the earlier guide log doesn't report the star lost but still has the bad trails: -

PHD2_GuideLog_2018-05-13_230718.txt

PHD2_GuideLog_2018-05-07_201058.txt

[Jkulin]

Just add I use a polemaster for my PA and that is always bang on, I also have a permanent pier so no movement on that either.

[RayD]

You can change the dec guiding type in PHD2 under the advanced tab in algorithms there is a dec guiding drop box.  This is normally set to Auto but you can change this to off or one direction only.

I'm not convinced this will be resolved with disabling dec guiding though.  It may be that you have a fair bit of float which means you need to balance East heavy and dec guide in one direction only.

[Jkulin]

Thanks Ray, I'll give it a go tonight and move the OTA back an inch or two.

How do I work out which way to guide so that I change it to the right direction?

[RayD]

Sorry John I meant North/South not East, that's for RA. 

I'm really not sure this will fix this if you are kind of rocking back and forth as that is normally a way to overcome a poor PA rather than a mechanical problem.  It may need a little trial and error to see which way is better or worse, but to me it looks like a bit too much play in the dec gears which may be easy enough to trim down.

[RayD]

If it is only happening near the zenith John it is more likely to be mechanical play and the guiding fighting against that.  It may be worth just trying it without dec guiding, but I would also check how tight your dec gearing is also as it looks like quite a bit to get trailing to that extent.

[Jkulin]

Thanks Ray, yes it only really appears near the Zenith, previously guiding has been excellent, I'll have a mess tonight.

When I did the backlash guide assistant, this is what I saved, not sure if it is any help: -

Is it easy to tighten the backlash up a wee bit, or beyond my abilities?

 

[RayD]

Yes it looks like it would help to adjust it John.  It isn't a very difficult job, just needing a couple of Allen keys, a gentle feel and a little patience.

There is a strip down guide on the AZ-EQ6 here which shows how the adjustments are made.

[Jkulin]

Thanks Ray, had a read of that guide a number of times, but can't see the DEC adjustments for backlash, its probably me being thick, but if you could point me in the right direction then it would be appreciated?

Thanks.

[Jkulin]

Well, made some adjustments and changed the weight distribution, guiding is look OK, first image off looks fine and the first image looks OK as well, so lets hope it continues: -

Fingers crossed it stays that way, will let you know.

[RayD]

Looks mile better John.  Fingers crossed! 

[Jkulin]

Well after getting to bed at 04:05 I'm pleased to say that the changes worked, the mount was fighting a little with the guiding after an hours or so, but it kept on track and none of the horrible problems previously.

I got nearly 3 hours of data last night and hopefully some more this week, I'm going to leave everything setup on the pier under a waterproof cover, then after I have about 6 hours I'll bring it all in and process.

I still have a small mod to do to the tilt plate in the left top corner, but not too fussed about that for now and will work on that another time.

So thanks for your help Ray.

[Jkulin]

I wish I hadn't opened my mouth, getting seriously cheesed off with this, as it was short lived and the star trails were back, why....God Knows!

We then changed the guide speed rate which was 0.1 to 0.5 and I couldn't get any guiding whatsoever, so dropped it down to 0.3 and it was better, but still not perfect.

I managed to get the final subs of M63 that I needed but what a palaver.

As we had more clear nights, I decided to recapture some more subs of M92 to add to some I took last year, everything started OK, then I dozed off to note the guiding off the scale, the logs show this happened during my 9 minute catnap, so went out to check everything and I couldn't get any guiding good enough to image with, I even tried with my QHY5-IIm and that was even more problematic as PHD complained I had set this up with a different guide speed and refused to operate, the only way round would have been to set up a new profiles, new dark library and then I could have tried.

These subs were only two minutes long rather than the 10 min ones of M63, so if it couldn't do 2 minutes, then what hope do I have of longer?

Now looking at the guide logs as attached, section 11 reports as follows: -

These figures look terrible compared to my mates log with similar equipment, but what really is of concern is the Polar Alignment, I use a QHY Polemaster and am always super critical setting this up and always previously it had been perfect, this figure should be less than .1"

I haven't done a 2/3 star alignment before to confirm this, but might need to learn how to do this, however am I correct in thinking that this can take time, something we don't have with these short nights?

Thoughts always welcome please?

PHD2_GuideLog_2018-05-20_002509.txt

[RayD]

1 hour ago, Jkulin said:

I wish I hadn't opened my mouth, getting seriously cheesed off with this, as it was short lived and the star trails were back, why....God Knows!

We then changed the guide speed rate which was 0.1 to 0.5 and I couldn't get any guiding whatsoever, so dropped it down to 0.3 and it was better, but still not perfect.

I managed to get the final subs of M63 that I needed but what a palaver.

As we had more clear nights, I decided to recapture some more subs of M92 to add to some I took last year, everything started OK, then I dozed off to note the guiding off the scale, the logs show this happened during my 9 minute catnap, so went out to check everything and I couldn't get any guiding good enough to image with, I even tried with my QHY5-IIm and that was even more problematic as PHD complained I had set this up with a different guide speed and refused to operate, the only way round would have been to set up a new profiles, new dark library and then I could have tried.

These subs were only two minutes long rather than the 10 min ones of M63, so if it couldn't do 2 minutes, then what hope do I have of longer?

Now looking at the guide logs as attached, section 11 reports as follows: -

These figures look terrible compared to my mates log with similar equipment, but what really is of concern is the Polar Alignment, I use a QHY Polemaster and am always super critical setting this up and always previously it had been perfect, this figure should be less than .1"

I haven't done a 2/3 star alignment before to confirm this, but might need to learn how to do this, however am I correct in thinking that this can take time, something we don't have with these short nights?

Thoughts always welcome please?

PHD2_GuideLog_2018-05-20_002509.txt

John,

The star alignment has nothing to do with PA.  I've found the Polemaster to be very good, but you can check it with a drift alignment in case yours has an issue as the noted error there is pretty high.

I'll have a look at the log to see if anything stands out.

[RayD]

Well looking at the log, John, it definitely seems that your PA is off.  I would also say that you have an issue with backlash which is preventing the guiding from settling, which happened a couple of times following a dither.

I'd start with a drift align to check whether your Polemaster is actually giving you the accuracy it is reporting.  Once you are confident PA is good, then look at the other issues. 

I would think that 5s is quite a long guiding exposure for your mount and would expect to see this around 2 - 2.5 second range (this is what I use on my AZ EQ6 with Lodestar X2).

[newbie alert]

I find east heavy doesnt help when the target is at zenith..not sure what the answer is so will follow if anyone has good suggestions

As a add on I'd suggest the drift align tool in phd as I find polemaster,sharpcap and phd2 drift align all differ from each other

[Jkulin]

Hi Thanks All,

Sorry Ray my error I meant drift alignment not Star alignment, had 5 days of frustration and getting to be between 03:00 and 04:30 so my brain is fried, I whipping the mount round to my mate this week, so will run a drift alignment and see what it reports and revert.

Thanks once again for all your help?

[RayD]

4 minutes ago, Jkulin said:

Hi Thanks All,

Sorry Ray my error I meant drift alignment not Star alignment, had 5 days of frustration and getting to be between 03:00 and 04:30 so my brain is fried, I whipping the mount round to my mate this week, so will run a drift alignment and see what it reports and revert.

Thanks once again for all your help?

No problem John.

Yes it is worth persevering with the drift align, even if it just to check the accuracy of your Polemaster.  I did this in my obsy on my Mesu by installing the Polemaster, getting PA as good as I could with that, then running a long drift alignment to see how it fared.  It was out a little bit, but not a lot, so I was then happy to ship it off to Spain where I use it on my AZ EQ6 which I have to set up each time I'm there.

Let us know what your friend says as he may be able to help you trim that backlash a bit also.

[souls33k3r]

@Jkulin are you using your refractor or your GSO?

If it's the refractor, i might know something you would want to try. Been there, done that, got the T-shirt.

[RayD]

53 minutes ago, souls33k3r said:

@Jkulin are you using your refractor or your GSO?

If it's the refractor, i might know something you would want to try. Been there, done that, got the T-shirt.

Don't leave us in suspenders here, I'm intrigued also 

[souls33k3r]

4 minutes ago, RayD said:

Don't leave us in suspenders here, I'm intrigued also 

hahahaha I was going to say if it's a refractor and like John says it's near to the zenith then it's the stoOooOoOopid balance in vertical axis. 

I had the same issue when imaging the rosette before i found out the real culprit. Just my two cents after logging on in nearly 5 days and going through 95 notifications

[RayD]

17 minutes ago, souls33k3r said:

hahahaha I was going to say if it's a refractor and like John says it's near to the zenith then it's the stoOooOoOopid balance in vertical axis. 

I had the same issue when imaging the rosette before i found out the real culprit. Just my two cents after logging on in nearly 5 days and going through 95 notifications

Ah yes I remember you having those issues my friend.  Tough to get right with a refractor as well as even an autofocus motor can send it off.

[Jkulin]

1 hour ago, souls33k3r said:

@Jkulin are you using your refractor or your GSO?

If it's the refractor, i might know something you would want to try. Been there, done that, got the T-shirt.

Hi, Thanks for the advice, in the last 6-7 sessions I have been using my Reflector an 8" RC, but with a focal length of 1625mm it does tend to bring out the errors.

I have previously had drift, but always managed to resolve using Metaguide and locking it down on a star.

My mate has an AZ-EQ6-GT as well, so I plan to take it over this week and compare his laptop setup guiding it and compare the logs vs. mine.

Hopefully as Ray suggested I'll trim the backlash as well.

Thanks Ray, yep if I don't get a chance whilst at my mates, then will do it myself and see how it fares.

I have seriously thought about sending it down to Dave at Dark Frames to get it hypertuned, and that would confirm any errors, it's £500 but if the issues prevail then it might be the answer.

[RayD]

6 minutes ago, Jkulin said:

Hi, Thanks for the advice, in the last 6-7 sessions I have been using my Reflector an 8" RC, but with a focal length of 1625mm it does tend to bring out the errors.

I have previously had drift, but always managed to resolve using Metaguide and locking it down on a star.

My mate has an AZ-EQ6-GT as well, so I plan to take it over this week and compare his laptop setup guiding it and compare the logs vs. mine.

Hopefully as Ray suggested I'll trim the backlash as well.

Thanks Ray, yep if I don't get a chance whilst at my mates, then will do it myself and see how it fares.

I have seriously thought about sending it down to Dave at Dark Frames to get it hypertuned, and that would confirm any errors, it's £500 but if the issues prevail then it might be the answer.

I had mine stellar tuned at Dark Frame and it is super smooth, but if it's only backlash it is easy enough to tune that yourself, John.

Hope the visit to your mate helps, it's a great idea.

[spillage]

I can only add the same as above. Run drift align both ways for at least 10 minutes to see how things are there and just tune out the backlash, take your time doing this and dont expect to remove it all with just a small fraction of a turn one you get close.

 

Mark.