Mount Bubble Accuracy? (Issues with good PHD2 graph)

[souls33k3r]

Hi All,

Keeping it simple, keeping it real, i don't trust the bubble level on my mount head (NEQ6 Pro).

The reason why i say this is i see the bubble indicator on the mount being right in the center but when i'm going my fine polar alignment adjustment (tightening the AZ bolts), i see the stars move slightly upwards.

When i set up my tripod, i just place it on the ground, then put the mount head and look at the bubble level. Presumably i'll be told that i need to level the tripod first but because i have to place my tripod on the grass, my thinking is that the tripod legs will sink in the ground when i place the mount head. I am happy to be corrected on this.

Assuming that i'll be told to level the tripod and use the proper spirit level, i was also wondering if there was any accurate Android/iPhone bubble level that someone can recommend?

Thanks in advance

[Dr_Ju_ju]

It doesn't have to be, and it doesn't matter if the mount base isn't level. Good polar alignment will take care of any discrepancies.

[souls33k3r]

4 minutes ago, Dr_Ju_ju said:

It doesn't have to be, and it doesn't matter if the mount base isn't level. Good polar alignment will take care of any discrepancies.

I was always told that one of the secrets on having a good PHD2 graph is to have the mount levelled. PA is another, balance is another one to add. For PA i'm using Polemaster which PHD2 never seems to agree with it which is a whole another kettle of fish.

[Dr_Ju_ju]

As long as PHD2 can keep track\correct the target in RA, in theory DEC should be constant, which relies on good PA, and so there should be no need for PHD2 to make DEC corrections.

A slight E\W imbalance will ensure that any gears are properly meshed, hopefully making the mount drive & any PHD2 corrections, as accurate as possible, to achieve the best guiding possible....

I also use Polemaster, and while I'm reasonable happy with my guiding, I don't doubt there are more accurate methods, e.g. drift alignment, but in the end it comes down to mechanically adjusting some bolts, which depending on size\thread and what they are acting on, stiction etc. will limit how accurate you can get it...

[knobby]

From what I know , level mount is important for Alt / Az but not relevant for an EQ ... Unless it's really out.

[souls33k3r]

5 minutes ago, Dr_Ju_ju said:

As long as PHD2 can keep track\correct the target in RA, in theory DEC should be constant, which relies on good PA, and so there should be no need for PHD2 to make DEC corrections.

A slight E\W imbalance will ensure that any gears are properly meshed, hopefully making the mount drive & any PHD2 corrections, as accurate as possible, to achieve the best guiding possible....

I also use Polemaster, and while I'm reasonable happy with my guiding, I don't doubt there are more accurate methods, e.g. drift alignment, but in the end it comes down to mechanically adjusting some bolts, which depending on size\thread and what they are acting on, stiction etc. will limit how accurate you can get it...

I do try to keep my mount imbalance in RA, but my Dec makes crazy corrections. 

I don't know if my scope isn't balanced properly (i always make sure it is) or is it just the mount.

My total RMS is always above 1.5" but my stars always look good. This does bother me a lot

1 minute ago, knobby said:

From what I know , level mount is important for Alt / Az but not relevant for an EQ ... Unless it's really out.

It's not massively out, just slightly i'd say. Basically i'm after a good PHD graph and i'm struggling here. I guess i'll change the topic name

[Ibbo!]

What exp are you using in PHD?

 

[Ouroboros]

I wonder whether this is problem with polar alignment rather than the mount? What method of polar alignment are you using. 

Total RMS of 1.5" isn't disasterous for a short focal length scope. I'd probably get round stars with that too .... and that's all that matters isn't it! I do slightly better than 1.5" RMS usually, as long as it's not windy. 

What worries me slightly is your concern that the tripod might sink in the ground. Before I put some flagstones down I used large plastic saucers under the tripod legs to spread the load. Might be worth a try. 

[souls33k3r]

4 minutes ago, Ibbo! said:

What exp are you using in PHD?

 

1.5 seconds .. i can stretch it to 2.5 but i'll get star loss message

4 minutes ago, Ouroboros said:

I wonder whether this is problem with polar alignment rather than the mount? What method of polar alignment are you using. 

Total RMS of 1.5" isn't disasterous for a short focal length scope. I'd probably get round stars with that too .... and that's all that matters isn't it! I do slightly better than 1.5" RMS usually, as long as it's not windy. 

What worries me slightly is your concern that the tripod might sink in the ground. Before I put some flagstones down I used large plastic saucers under the tripod legs to spread the load. Might be worth a try. 

I'm using polemaster for my PA.

I agree, in the end round stars is all what matter but i'd love to see a better graph and i think something is a miss here. I did have a stiff dec not long ago so i had to unscrew the puck at the counter weight shaft, unscrewed it a little which has made dec saddle smooth but i do notice that when there is no scope on the saddle and only counter weights, the dec does move freely. Not sure if it's meant to do that. I might have to tighten the dec saddle a bit. What are your thoughts?

A friend of mine has given me some weird plastic thingies to make sure my tripod doesn't sink in the ground which i am using them right now.

[Ibbo!]

I would do a drift align one moon affected night just to test it out .

 

 

DA can be done fairly quickly if you practice.

 

Another factor in the misx is if you have excessive backlash in the Dec axis.

[souls33k3r]

7 minutes ago, Ibbo! said:

I would do a drift align one moon affected night just to test it out .

 

 

DA can be done fairly quickly if you practice.

 

Another factor in the misx is if you have excessive backlash in the Dec axis.

Never done DA tbh, i have to set up and tear down every session and i'm a bit afraid of doing it because it will be just time consuming (trust me, i've read some horror stories).

I'm sure there is backlash in dec, not sure if making the scope slightly back heavy would help?

[RolandKol]

20 minutes ago, souls33k3r said:

1.5 seconds .. i can stretch it to 2.5 but i'll get star loss message

I'm using polemaster for my PA.

I agree, in the end round stars is all what matter but i'd love to see a better graph and i think something is a miss here. I did have a stiff dec not long ago so i had to unscrew the puck at the counter weight shaft, unscrewed it a little which has made dec saddle smooth but i do notice that when there is no scope on the saddle and only counter weights, the dec does move freely. Not sure if it's meant to do that. I might have to tighten the dec saddle a bit. What are your thoughts?

A friend of mine has given me some weird plastic thingies to make sure my tripod doesn't sink in the ground which i am using them right now.

Have you tried bin x2?

What is the PHD2 and EQMOD track rate? try using the same values.

I had to setup new laptop recently, + in addition placed Canon + Samyang on my 130PDS, due to that was made to go for OAG,  and my NEQ6 went insane.... It was Also around 1.5 Total RMS in guiding...

2.5sec x2bin, 0.3 guide rate on both EQMOD and PHD2, - 3 star sync, calibrate, drift align, re-calibrate, PHD guiding assistant (which also accounts for backslash) = 0.65 RMS. Give a try.... will take good 2 hours in total... but the Moon is full so have fun

[RolandKol]

7 minutes ago, souls33k3r said:

Never done DA tbh, i have to set up and tear down every session and i'm a bit afraid of doing it because it will be just time consuming (trust me, i've read some horror stories).

I'm sure there is backlash in dec, not sure if making the scope slightly back heavy would help?

P.S.

I afraid to touch my tripod after!

Simply cannot imagine myself going through all the routine before each session...

[souls33k3r]

9 minutes ago, RolandKol said:

Have you tried bin x2?

What is the PHD2 and EQMOD track rate? try using the same values.

I had to setup new laptop recently, + in addition placed Canon + Samyang on my 130PDS, due to that was made to go for OAG,  and my NEQ6 went insane.... It was Also around 1.5 Total RMS in guiding...

2.5sec x2bin, 0.3 guide rate on both EQMOD and PHD2, - 3 star sync, calibrate, drift align, re-calibrate, PHD guiding assistant (which also accounts for backslash) = 0.65 RMS. Give a try.... will take good 2 hours in total... but the Moon is full so have fun

Yes i am using bin x2 for the guidecam. It's a QHY5L-ii Mono.

Sorry where will i find the PHD2 and EQMOD track rate? If you can point me in the right direction for both, i'll get this information (Sorry i'm fairly new to PHD2).

I do the calibrate every time but usually where i'm going to be capturing subs. I do also use PHD guiding assistant (leave it running for 2 minutes) and then accept the settings. DA is the only thing i haven't touched base yet.

Wish i had the luxury of leaving my kit out in one place.

[RolandKol]

1 minute ago, souls33k3r said:

Yes i am using bin x2 for the guidecam. It's a QHY5L-ii Mono.

Sorry where will i find the PHD2 and EQMOD track rate? If you can point me in the right direction for both, i'll get this information (Sorry i'm fairly new to PHD2).

I do the calibrate every time but usually where i'm going to be capturing subs. I do also use PHD guiding assistant (leave it running for 2 minutes) and then accept the settings. DA is the only thing i haven't touched base yet.

Wish i had the luxury of leaving my kit out in one place.

On PHD, simply start a new profile wizard, it will walk you through and will suggest 0.5 track rate.
Eqmod, by default has 0.1 track rate, - so I hit the middle for both, it may be a bit different for your setup of course, - experiment with different values by setting up different profiles in PHD2,

once happy, delete the rest.

Completely forgot, - dark library on PHD2 also helps.

I like to re-read this PHD summary, - short and effective - https://openphdguiding.org/PHD2_BestPractices.pdf

[souls33k3r]

8 minutes ago, RolandKol said:

On PHD, simply start a new profile wizard, it will walk you through and will suggest 0.5 track rate.
Eqmod, by default has 0.1 track rate, - so I hit the middle for both, it may be a bit different for your setup of course, - experiment with different values by setting up different profiles in PHD2,

once happy, delete the rest.

Completely forgot, - dark library on PHD2 also helps.

I like to re-read this PHD summary, - short and effective - https://openphdguiding.org/PHD2_BestPractices.pdf

Top man, much appreciated. 

I'll go home and check these settings.

I did have a read of the best practise a while ago, but i guess it's due for another read

One question that i did ask above was "I did have a stiff dec not long ago so i had to unscrew the puck at the counter weight shaft, unscrewed it a little which has made dec saddle smooth but i do notice that when there is no scope on the saddle and only counter weights, the dec does move freely. Not sure if it's meant to do that. I might have to tighten the dec saddle a bit. What are your thoughts?". Basically i've never known my mount (since i've started AP) to be anything but in this condition.

[RolandKol]

Not sure... 

I think if it does not wobble while clutches are On, - it should be OK.

My does a bit in RA, noticed it when it was cold, but I have not touched it as guiding was OK.

The main issue I usually have, - balance.... Piggyback camera, plus autofocuser, Mono setup, does shift the center of the gravity drastically with Newtonian.

In your case... I guess, it does not have such an impact as all is at the bottom an easily balanced.

One thing I noticed, my NEQ6 guides a bit better if counterweight shaft is IN as much as possible.... I used one counterweight initially, but ended up using two with shaft almost full IN, - even if it is 5kg more, but balanced with a shorter shaft makes motor's life easier.

Another thing, tripod legs, - do not use full length, - lower as much as possible.

And do Drift Align... You will need to adjust altitude only once (or twice to pin point it later), so you will need to deal with RA mainly.

P.S.

And my Mount does not like to be East/West heavy at all... not a bit... it loves the perfect balance,  - like salty peanuts and the pint of  beer on the Friday evening...

 

 

[Ouroboros]

2 hours ago, souls33k3r said:

1.5 seconds .. i can stretch it to 2.5 but i'll get star loss message

I'm using polemaster for my PA.

I agree, in the end round stars is all what matter but i'd love to see a better graph and i think something is a miss here. I did have a stiff dec not long ago so i had to unscrew the puck at the counter weight shaft, unscrewed it a little which has made dec saddle smooth but i do notice that when there is no scope on the saddle and only counter weights, the dec does move freely. Not sure if it's meant to do that. I might have to tighten the dec saddle a bit. What are your thoughts?

A friend of mine has given me some weird plastic thingies to make sure my tripod doesn't sink in the ground which i am using them right now.

My DEC axis does not rotate completely freely either unless I rotate the RA axis so that the telescope and counterweight shaft are horizontal. In this position I can set the telescope balance very accurately by moving the telescope backwards and forwards along the saddle.  It goes without saying that this balance is set as in 'imaging mode' with camera, guide cam etc attached.  

[Ibbo!]

Have you a log of your guiding ?

[RolandKol]

My mount went mad today...

It simply did not want to guide better than 1.5 RMS on usual 3sec...

changed to 1sec for drift alignment.... and even did not started it!!!! As people say, if it works, - do not touch!!!

some kind of nonsense...
never had such results with 1sec...

[michael8554]

Sorry, really do not understand the point you are trying to make ?

Michael 

[RolandKol]

The point was...

Sometimes, usual/common settings from the "vocabulary" simply do not work.

All manuals state, - guide with 2 - 4 sec exp, and if fact, my NEQ6 performed just like manuals stated, - best guiding results were at 3 or 3.5 sec exposures,

but not yesterday... as it wanted to guide properly only on 1sec... if I switched it back to 3sec, total RMS went back to 1.5, with peaks up to 2... and graph was simply all over the screen.... Insane...

[michael8554]

12 hours ago, RolandKol said:

as it wanted to guide properly only on 1sec.

So in your 1sec graph above it's "guide {ing} properly" ?

Or when you moved back to 3.5 secs ?

Did you change the settings when you dropped to 1sec ?

The RA is yoyo-ing, suggesting the settings are too aggressive for the seeing.

But on 1 sec the RA RMS is 0.42 arcsecs, which is way better than "1.5" ???

Michael 

[RolandKol]

Nope, have not changed anything but the exposure.

and yes,  if I go back to my usual 3.5sec my Graph Screen becomes almost completely red with the graph all over the place.

As per RA aggressiveness, my mount has a slight wobble in RA with the clutches ON, will have to fix it after May

P.S.

0.55 Total RMS for NEQ6 is not good enough? So what is the limit?

I never even tried to go further down for my 130PDS+ASI1600, but it would be an interesting challenge.

I have round stars even at 1.5 total RMS, but i do not feel confident if the graph is all over the screen, so I simply try to keep it under 0.8

[michael8554]

Interesting, 

You need to add some figures to "screen becomes red", could be anything.

I suggest you post your PHD2 guide log and debug log on the google Open PHD Guiding forum, Bruce and Andy the PHD2 developers will give you guidance.

Those logs should ideally include a Calibration.

Michael