My boring guiding problems

[Carole]

Going back to this annoying topic.

As you can see from the recent images I've posted,  guiding does work some of the time.  However it quite often fails to calibrate in Dec and it can be several tries before it starts guiding and then it takes a few minutes to settle down and then eventually seems to work fine.

It's the failure to calibrate in Dec which is driving me bananas as sometimes it just will not calibrate at all in one part of the sky and so I try a different target and sometimes it will work OK straight off and sometimes it will take a couple of tries.  

It's not always the same part of the sky I have trouble with calibration, One night it won't calibrate for M81 and another night it won't calibrate for M42 or M1, then another night it will be around the other way.

Since these troubles all started several months ago I now have a new guide camera, new cables, removed the hub, a regulated power supply and last night I tried my other mount and got the same problem with that too, which surely has to rule out the mount.

I have tried taking a dark frame in PHD, moving the weights so it's East heavy, I've tried changing the settings in PHD, I've tried switching on the guiding before opening up the DSLR capture programme.

I did think for a short while that the mount wasn't in the Northern hemisphere (after a Restore to Factory Settings) but that seems to have been a red herring and it was in fact in the right place.

The only thing I haven't looked at is the guide rate within the mount handset itself because I don't know what these settings should be.

Any offers of assistance or advice would be greatly appreciated.

thanks

Carole

[Mike]

It looks to me like you have the settings wrong in PHD.

One thing you haven't said you have tried, is different software. Why not try K3CCD or GuideMaster?

http://www.pk3.org/Astro/index.htm?k3ccdtools.htm

http://www.guidemaster.de/index_en.asp

[MarkS]

Carole,

When I previously looked at your PHD log file, it was very clear that PHD was sending move commands to the mount (in Dec) but there was no movement in the mount (indicated by guidestar moving in frame).

Next time it fails to calibrate,  try slewing the mount manually from the laptop in Dec with with guide camera updating the screen so you can watch the star (there may be Left Right Up Down buttons in PHD - I don't remember - but if so use these).   My best guess is that you have an intermittent connection failure (broken lead somewhere?) or some intermittent elecromecahincal problem in the mount itself.

Mark

[Carole]

It looks to me like you have the settings wrong in PHD

I have in the past posted a screen shot of this, but no-one came back to me saying anything was wrong.
I'll post another one.

is different software. Why not try K3CCD or GuideMaster?

PHD is so easy to use, and works for every-one else, so I can't see why it shouldn't work for me.  But if all else fails I could give that a try.  I already have K3CCDtools and looked at the guiding on that, but did not look very user friendly.  

some intermittent elecromecahincal problem in the mount itself.

In both mounts?

broken lead somewhere?)

All cables have been changed.  

WHAT SHOULD THE GUIDE RATE BE?

Meanwhile I'll upload my "brain" settings in PHD.
I'll also do that manual slewing test you suggested Mark when we get some stars . (I've already done the same test in the daytime and listened to the mount.  

Mike/Robert, would you be kind enough to take a look when we are in Kelling (of course once you've sorted your own imaging out and I know Mike will be trying to get his head round a new set up which I am happy to help with on the DSLR side Mike).  

Thanks

Carole

[MarkS]

In both mounts? 

All cables have been changed.  

We're narrowing this down:

What do you have that goes from the USB to the mount (or from serial to the mount).  I have an adapter from Shoestring - what do you use?

Mark

[Carole]

What do you have that goes from the USB to the mount

I used to use a GPUSB, but since I bought the QHY5 I use the ST4 cable direct to the guide port so no connection at all between USB and Mount (N.B. I have two of these cables (one is an RJ12 but I am told these are the same) and same problem with both.  

My current settings.  N.B. I used to have MAX DEC duration set at 150 but some-one suggested upping it to 500 and I have have gradually increased up to the current level and this made no difference.




Carole

[The Thing]

Hi Carole,

For Comparison, here are my settings. I do have a very different mount and low aggressiveness seems to work for me. Also you could update PHD to 1.12.3, though that probably won't make any difference. My experience of DEC problems has always been no commands getting from laptop to scope. Maybe you could borrow someone else's guide cam to try in case your QHY5 is not outputting DEC signals?

[Carole]

Well on the Dec side I seem to have the same settings as you Duncan apart from Max Dec duration which has been through a range of settings in my endeavours to try to solve this problem.

This is a brand new QHY5 with a brand new download of PHD.
As an exercise I could go back to my old guide camera and GPUSB cable and see if I get the same failure in Dec and see if I'm still getting the same problem, but I was certainly getting problems beforehand, but worse ones.

But it doesn't make sense that eventually it does work and guides OK.
Perhaps I could add you to the "look over my shoulder" list of helpers at Kelling Duncan, as you are now going.

Thanks

Carole

[Mac]

Quote

some intermittent elecromecahincal problem in the mount itself.

In both mounts?

Ah, there be your problem, 99.9% of people never assume that they have two separate problems in two places, (this catches out people at work)
they assume that there is just one common problem, and then spend an age trying to find a single common problem that doesnt exist,
rather then find the two separate problems.

Not saying both your mounts are faulty, but it might be just that, they both are.

Just a thought.

Mac.

even worse if they are intermittent.

[Carole]

Not saying both your mounts are faulty, but it might be just that, they both are.

Oh Gawd!!

even worse if they are intermittent.

See what I'm up against!

Might be a good idea to try my guiding kit out on some-one else's mount, i.e a mount that is NOT a CG5 GT (Both my mounts are CG5 GT), possibly an HEQ5 if I can persuade some-one to let me have a go with theirs.  

Mike as you're selling your EQ6, any chance of having a try with that before it goes?
Although if it works fine on yours you might even have found yourself a buyer

Carole

[mickw]

Has nobody on the other forums, UKAI, SGL etc, offered any possible solutions ?

With the thousands of members the odds of finding someone with same kit is quite good

[Carole]

Tried that Mick, which is where some of the things that I have tried out have come from.

I will however try targetting those with CG5 GT mounts who actually guide.

Carole

[mickw]

Are all your cables free from obstructions  ?
Just moving a cable could mess up the connection.

All of my cables are attached to the mount/scope with a velcro wrap leaving enough slack to actually plug them in.
If a cable snags on tripod leg or whatever, it pulls on the velcro rather than the connector.

[Jim]

Carole

Have you adjusted the backlash settings? If the dec worm gear has some play in it then PHd will think it's not moving. Here's the txt from the manual for Celestron mounts.

<<Anti-backlash – All mechanical gears have a certain amount of
backlash or play between the gears. This play is evident by how long it
takes for a star to move in the eyepiece when the hand control arrow
buttons are pressed (especially when changing directions). The CGE
PRO anti-backlash features allows the user to compensate for backlash
by inputting a value which quickly rewinds the motors just enough to eliminate the play between gears. The amount of
compensation needed depends on the slewing rate selected; the slower the slewing rate the longer it will take for the star to
appear to move in the eyepiece. There are two values for each axis, positive and negative:

Positive is the amount of compensation applied when you press the button, in order to get the gears moving quickly without a
long pause.

Negative is the amount of compensation applied when you release the button, winding the motors back in the other direction
to resume tracking.

Normally both values should be the same. You will need to experiment with different values (from 0-99); a value between 20
and 50 is usually best for most visual observing, whereas a higher value may be necessary for photographic guiding.
To set the anti-backlash value, scroll down to the anti-backlash option and press ENTER. While viewing an object in the
eyepiece, observe the responsiveness of each of the four arrow buttons. Note which directions you see a pause in the star
movement after the button has been pressed. Working one axis at a time, adjust the backlash settings high enough to cause
immediate movement without resulting in a pronounced jump when pressing or releasing the button. Now, enter the same
values for both positive and negative directions. If you notice a jump when releasing the button, but setting the values lower
results in a pause when pressing the button, go with the higher value for positive, but use a lower value for negative. The
telescope will remember these values and use them each time it is turned on until they are changed.>>

[RobertM]

that's a good theory Jim and what I was thinking but PHD works out what the backlash is and compensates for it.

Carole, does PHD calibrate correctly when you initially setup ?  I have always found that guiding is hit and miss (even on my mount) if the mount doesn't move enough during the initial setup.  It isn't so much of a problem with longer focal lengths but for shorter fl guide scopes it can be.  In MaximDL this can be adjusted by setting the length of calibration time and guide rate.  At present I set the cal time to maximum to ensure that the mount moves as far as possible so I get accurate corrections.  That gives me corrections of +/-0.01 pixel at the guide scope (200mm f/l) unless the conditions are bad.

To me it looks like this is an area you need to check in PHD.  I know I fumbled around with the settings when I used it a couple of years ago before getting it right.

Hope that helps
Robert