Help with PHD2

[kman42]

Hi, I am trying to get my guiding setup working properly. I am using stepper motors to drive an EQ5, via an AstroEQ box and PHD2.

So far, I can get my laptop to move the mount manually via the EQMod slew controls, and everything seams to move in the right direction at the rate it should.

However, when I try to calibrate the mount, PHD2 never seems to be happy with it (either 'calibration was based on very few steps', or 'angles are questionable').

If i then start guiding, PHD2 quickly says that it was unable to make sufficient corrections in RA/DEC.

When I use the guiding assistant, it says my alignment error is massive. like, around 100,000 arc-min; But I am pointing fairly well at the south pole.

The weird thing is that if I leave the mount guiding, I can hear the DEC stepper motor make ongoing corrections, but I can only hear the RA stepper motor make a large correction every 20-30 seconds - even though it powers normally when being controlled manually via EQMod.

Any ideas? And yes, I have double checked that I  haven't RA and DEC switched around.

[michael8554]

G'day !

Read this:

https://openphdguiding.org/phd2-best-practices/

Calibration is carried out at Dec 0, not Dec 90 the South Celestial Pole !!

The stars are hardly moving at Dec 90 so PHD2 will struggle to Calibrate.

Also check out the PHD2 Static Polar Alignment, created by Ken Self from Oz because of the lack of a convenient Pole Star down under.

Michael

[kman42]

If i understand this right, you're saying I should have the guide scope pointed just about straight up for good calibration? I had been calibrating at 0 Dec but down low near the horizon. 

I have been working through the best practices but obviously got stuck at the calibration step. They seem to suggest I can do a rough polar alignment, calibrate the scope, then do a good drift alignment after that? Is that the right order? I'm guessing I would need to recalibrate after drift alignment. 

[almcl]

10 hours ago, kman42 said:

Hi, I am trying to get my guiding setup working properly. I am using stepper motors to drive an EQ5, via an AstroEQ box and PHD2.

Good man!  I use the same set up (AstroEQ and NEMA  steppers on an EQ5) for my widefield imaging.

Have you set up the new equipment profile with the correct figures?  I ask because a common slip is to input the wrong guidescope focal length.  This can lead to PHD2 miscalculating the number of steps.  The other thing is to nudge the scope in DEC in whichever direction it calibrates in the southern hemisphere (it's north in the northern hemisphere but not sure about the southern) until you see the selected star move, before starting a calibration.  This helps with the often quite large amount of backlash that the EQ5 can suffer from.

11 hours ago, kman42 said:

If i then start guiding, PHD2 quickly says that it was unable to make sufficient corrections in RA/DEC.

Try getting PHD2 to carry out a starcross test and see what that looks like?  That will at least confirm that it is able to move in all directions.

[kman42]

1 hour ago, almcl said:

Have you set up the new equipment profile with the correct figures?  I ask because a common slip is to input the wrong guidescope focal length.  This can lead to PHD2 miscalculating the number of steps.  The other thing is to nudge the scope in DEC in whichever direction it calibrates in the southern hemisphere (it's north in the northern hemisphere but not sure about the southern) until you see the selected star move, before starting a calibration.  This helps with the often quite large amount of backlash that the EQ5 can suffer from.

I am using a Helios M44-2 for my guidescope. It says 58mm on the lens, which is what I enter into PHD2. Hopefully the Russians report their lenses correctly...

I will try clearing the backlash, although the Guiding Assistant says my backlash is 'low'.

I'll try the starcross test too.

Once I've selected a guide star & calibrated, do I just press 'guide' in PHD2 and it should work? Is there anything I should select on the EQMod window, or are these buttons unrelated to guiding??

[michael8554]

2 hours ago, kman42 said:

I had been calibrating at 0 Dec but down low near the horizon.

The way I read your original post I thought you meant you had Calibrated pointing near to the SCP.

2 hours ago, kman42 said:

you're saying I should have the guide scope pointed just about straight up for good calibration?

No I said Calibrate at Dec 0.

If PHD2 doesn't move the scope far enough at Dec 0 then have you have entered a sensible Guide Rate setting? 50% or more of Sidereal ?

Michael

[kman42]

6 minutes ago, michael8554 said:

The way I read your original post I thought you meant you had Calibrated pointing near to the SCP.

No I said Calibrate at Dec 0.

If PHD2 doesn't move the scope far enough at Dec 0 then have you have entered a sensible Guide Rate setting? 50% or more of Sidereal ?

Michael

Calibration at Dec 0 makes sense. Does the RA position matter much?

Where do I enter the guide rate setting??

[michael8554]

Usually you Calibrate with RA within 1 hour of the meridian.

PHD2 then adjusts its guiding to whatever position you eventually guide at - so long as your mount reports it's actual RA and Dec back to PHD2.

If not it is best to Calibrate on a star near the target you will be imaging.

I'd guess that EQMod has a Guide Rate setting, never used EQmod myself. Probably a load of settings in EQMod you have to get right too.

Not sure but this might be what you need:

https://github.com/OpenPHDGuiding/phd2/wiki/EQASCOM-Settings

58mm FL is on the short side for a guidescope, but PHD2 should cope if you have that FL and the correct pixel size entered before Calibrating.

Michael

 

[almcl]

7 hours ago, kman42 said:

I am using a Helios M44-2 for my guidescope. It says 58mm on the lens, which is what I enter into PHD2. Hopefully the Russians report their lenses correctly..

That's a camera lens, right?  That focal length may relate to its use with a 35mm film or dslr camera so you may need to experiment to find out how it  works with your guide camera.

[michael8554]

That's the Crop Factor you're thinking of. 

Doesn't alter the focal length, 58mm is correct. 

There may be a good reason for the introduction of the term Crop Factor,  but in my opinion it's meaningless advertising hype..... 

Michael 

[kman42]

12 hours ago, michael8554 said:

That's the Crop Factor you're thinking of. 

Doesn't alter the focal length, 58mm is correct. 

There may be a good reason for the introduction of the term Crop Factor,  but in my opinion it's meaningless advertising hype..... 

Michael 

This was always my understanding - 58mm is the physical size of the magnification.

After some more research I have come to realise that I think I need to engage sidereal tracking on EQMod, after which I should go through the guiding steps on PHD2. Seems like a basic thing to miss, but believe it or not this is not mentioned in any tutorials! I'll give this a try when I next get a chance.

[cletrac1922]

On 17/03/2020 at 21:20, kman42 said:

Hi, I am trying to get my guiding setup working properly. I am using stepper motors to drive an EQ5, via an AstroEQ box and PHD2.

So far, I can get my laptop to move the mount manually via the EQMod slew controls, and everything seams to move in the right direction at the rate it should.

However, when I try to calibrate the mount, PHD2 never seems to be happy with it (either 'calibration was based on very few steps', or 'angles are questionable').

If i then start guiding, PHD2 quickly says that it was unable to make sufficient corrections in RA/DEC.

When I use the guiding assistant, it says my alignment error is massive. like, around 100,000 arc-min; But I am pointing fairly well at the south pole.

The weird thing is that if I leave the mount guiding, I can hear the DEC stepper motor make ongoing corrections, but I can only hear the RA stepper motor make a large correction every 20-30 seconds - even though it powers normally when being controlled manually via EQMod.

Any ideas? And yes, I have double checked that I  haven't RA and DEC switched around.

Hi Buddy

If you in South East Queensland, then rock up to one of our local clubs, members their only too helpful assist

Sirius Optics also have a monthly night at their Underwood store, and very knowledgeable club members attend as well

John

 

[kman42]

Ok, so had a go tonight and it turns out a) that I do indeed need to be running the EQMod tracking while in PHD2, and b) the EQMod was tracking in the wrong direction. I can now get sensible results from calibration and the Guiding Assistant.

Next questions are about drift alignment. I'm seeing "current scope pointing" numbers that don't make a lot of sense to me. When I go to adjust the Altitude, it wants me to slew to 0 DEC, and thinks I am at 90 DEC, but I am pointing at the Equator??

aside from that,

1. How does PHD2 'know' where I'm pointing?

2. Can I manually move my mount to where it is asking? As in, unlock the RA and DEC gears and rotate the mount head where I need it to. Or will that stuff it up?

[michael8554]

1.  If you have a data connection between the mount and the PC, then PHD2 should know where the mount is pointing. 

To check, open the Drift Align feature in PHD2. A  window should open showing the current mount position, and an option to move to Dec 0 and the Meridian. 

3 hours ago, kman42 said:

Next questions are about drift alignment. I'm seeing "current scope pointing" numbers that don't make a lot of sense to me. When I go to adjust the Altitude, it wants me to slew to 0 DEC, and thinks I am at 90 DEC, but I am pointing at the Equator??

If the window says Dec 90  and you're already pointing at Dec 0, sounds like the mount isn't correctly reporting it's position. 

2.  Depends when you want to do this. After you've S Itar Aligned the mount won't know where it is anymore. 

To centre the first Alignment star you can centre with the handset or by releasing the clutches, but the next star(s) should be centred with the handset. 

Michael 

Edited March 19, 2020 by michael8554

[kman42]

So it sounds like the calibration process tells PHD2 where the mount is? And once I've calibrated, I shouldn't move manually using the clutches. 

How would I troubleshoot / fix the mount correctly reporting its position? 

[TerryMcK]

The calibration process works out which direction and how far to move the RA/DEC to keep the guide star on target. You can dismantle the telescope and tripod, move it somewhere else and when you reassemble the scope PHD2 still knows how far and in which direction to nudge the motors. That is assuming you keep the guide scope/guide camera in the same orientation and you haven’t changed that guide camera or guide scope.

Edited March 19, 2020 by TerryMcK

[kman42]

Thanks Terry, I was misunderstanding the role of calibration - am I correct in saying that it calibrates for the equipment, not location?

7 hours ago, michael8554 said:

1.  If you have a data connection between the mount and the PC, then PHD2 should know where the mount is pointing. 

To check, open the Drift Align feature in PHD2. A  window should open showing the current mount position, and an option to move to Dec 0 and the Meridian. 

But how does it get this information? Is it extrapolated from the calibration process? Otherwise there must be a GPS or something telling it where it is...

[michael8554]

We're at cross-purposes with "where it is".

I mean the RA and Dec positions, sorry if I lead you to think I meant  the Lat and Long of your location, that to me was something I'd assumed you'd already entered into EQMod right at the start.

The RA and Dec position where the mount is pointing is information the mount supplies once it's correctly Star Aligned  - I don't mean PHD2 Calibrated, you seem to be using the terms Calibration and Alignment as the same thing, they're not.

And you can check in the Drift Align as already mentioned, maybe EQMod shows it too ?

Michael

 

[kman42]

1 hour ago, michael8554 said:

We're at cross-purposes with "where it is".

I mean the RA and Dec positions, sorry if I lead you to think I meant  the Lat and Long of your location, that to me was something I'd assumed you'd already entered into EQMod right at the start.

The RA and Dec position where the mount is pointing is information the mount supplies once it's correctly Star Aligned  - I don't mean PHD2 Calibrated, you seem to be using the terms Calibration and Alignment as the same thing, they're not.

And you can check in the Drift Align as already mentioned, maybe EQMod shows it too ?

Michael

 

Sorry, yes we're interchanging a few terms here. My confusion summarised: How does PHD2 have any idea where the telescope is a) pointing, and b) physically located? It reports current RA and DEC position in the drift alignment tool. How does it come up with these numbers? And surely these positions are dependant on both where you are pointed and where you are located on the earth? Or am I mistaken on this? 

Also, you mention that Lat and Long need to be entered into EQMod - I have done this, however this made EQmod run sidereal tracking in reverse. I had to change my location from South to North to get the correct rotation.

 

[Merlin66]

I'm using both PHD2 and EQMod in Oz...no issues with Long/ lat (38 south, 144 East) and if the Aux setting is used in PHD2 ( set to EQmod ASCom Heq5/6) then this is where it gets the info from the mount.

Just check that RA reverse is not ticked in EQMod

 

[TerryMcK]

8 hours ago, kman42 said:

Thanks Terry, I was misunderstanding the role of calibration - am I correct in saying that it calibrates for the equipment, not location?

Yes

[kman42]

46 minutes ago, TerryMcK said:

Yes

OK, so that just leaves my question of HOW does PHD2 come up with the values it reports in the Drift alignment tool for your current RA and DEC? Where is it getting that information? 

[TerryMcK]

I don't use the drift alignment tool so can't comment. 

[Merlin66]

See my reply above.....

[michael8554]

There's a "Get Position" type poll in the PHD2 driver, to get the info from the mount's drive system. 

By Position it means RA and Dec. 🙂

6 hours ago, kman42 said:

I had to change my location from South to North to get the correct rotation

Your South Lat location might have to be set in the handset, or in EQMod, as a minus or S  in the numerals input. 

And as already said several times, the RA reverse setting needs to be correct. 

Michael