Finder guiding issues with a Lodestar

[RobertM]

Could also be stiction or too much backlash (or a combination of both).

[MarkS]

Could also be stiction or too much backlash (or a combination of both).

Stiction yes, backlash hopefully not (at least in R.A.) as long as the setup is weighted slightly heavier on the East to maintain load on the gears.

[The Thing]

I used to get this sort of sub on my HEQ5 before I upgraded all the bearings. £75 well spent.

[Rocket Pooch]

The reason I made the comment is that for most of the sub the guiding is ok, then there movement, like something catching and releasing, or as mark says a possible over balance.

I won't go into the other issue because that will cause a heated debate.

Last thing Ivor you might want to remove the location of your kit of this thread.

[Ivor]

Thanks for the ideas I'm going to Mark's tomorrow night so hopefully we'll be able to sort it out then.

Last thing Ivor you might want to remove the location of your kit of this thread.

Thanks missed that, I have updated it to a more secure location

[MarkS]

Thanks for the ideas I'm going to Mark's tomorrow night so hopefully we'll be able to sort it out then.

If anyone else is at a loose end and fancies paying a visit this evening, you're more than welcome.  Remember it's a full moon though.

Mark

[MarkS]

OK, for the benefit of all, here is what we've found so far - mainly by looking at the PHD log file you generated with the Lodestar on the main imaging scope - 1.65arcsec/pixel.

1) With an guide camera exposure time of 0.5sec, there was anything from 0.75sec to 4sec between frames (average time between frames was 1.5 sec).  4 seconds is a serious lag in the feedback loop!  I suspect this is waiting time caused by other applications.

Is your laptop a dual core?  Is it possible that raising the priority of PHD and EQMOD might help prevent these waits?
With my old single core and underpowered laptop I often found that opening a downloaded sub-exposure from the main imaging camera would screw up the guiding.

2) Errors of more than 6 pixels (10 arcsec) in R.A. were quite common

3) We still need a PHD log done with guide pulses switched off.  This will allow a PE graph to be generated which will check if the mount itself is behaving OK.

Mark

[Ivor]

Additional comments & answers

1) my laptop is an i5, so upping their priority shouldn't be an issue. I normally have AA5, PHD2, CduC, EQMOD, Chrome, AVG and some times teamviewer. During recent tests AA5 has been running but not taking subs so the overheads should be low.

3) We discover that PHD2 log files are formatted differently to PHD ones, PECPrep can read them but the output is wrong. Hopefully the weekend will be kind and give me a sufficient slot to test this.

[MarkS]

1) my laptop is an i5, so upping their priority shouldn't be an issue.

I wonder what is causing those "wait" periods then?

[mickw]

Any tabs open in Chrome ?

Google seems to spend most of it's time searching for ads. for "appropriate" goods for you

[Mac]

Download the following process monitor.

http://technet.microsoft.com/en-us/sysinternals/bb896645

and run it, it will tell you which process is hogging all the cpu time.
I've also found out the following.
If something needs to be backwards compatable it will normally open a hidden command prompt.
And doesn't shut it down, this command prompt SLOWS windows 7 down to a crawl.
You might have one of these open.

Mac.

[Fay]

where is PHD 2 for downloading? Cant see it.  Thanks

[MarkS]

You'll find it here:
http://openphdguiding.org/

[Ivor]

It's amazing what a cycle home does to clear the mind on a blustery night.

Download the following process monitor.

http://technet.microsoft.com/en-us/sysinternals/bb896645

Thanks, I'll give it a go.

I wonder what is causing those "wait" periods then?

If you recall we found PHD2 was losing the star more frequently than we expected, I wonder if the longer gaps relate to that?

I've copied the configuration across to PHD ready but the gusts a bit too strong tonight so hopefully tomorrow. Just to check I've got it right to create the file for PECPrep I take the following steps:

• Run PHD
• Open brain and select "Disable guide output"
• Under tools check enable logging
• Connect to camera and scope
• select star
• Leave for a minimum of 40 mins

Anything else?

[MarkS]

Start PHD
Connect to camera and scope
Enable logging
Calibrate on a star
Disable guide output
Select star and start "guiding"
40 min of data is fine

It is certainly possible that the "gaps" are linked to losing the star - I don't really know what PHD does under those circumstances.