First Time Using PPEC LX200GPS 10" OAG w/ 0.63FR

[Jed Danyliw]

https://openphdguiding.org/logs/dl/PHD2_logs_qgc9.zip

Hello all, latest setup after taking recommendations from previous sessions.  Please observe and advise.

Jed

PS, seeing was average-poor

[mj.w...@gmail.com]

Hi Jed

I have an 8" LX200GPS @ f/0.63, so can relate to your problems.

You seem to have spent about 45 minutes getting PA down to 5arcmins.

How are PA-ing ?

If this is a non-permanent setup you might consider a much faster method, such as SharpCap with a separate wideangle guidescope, I don't think the OAG setup gives a wide-enough FOV.

On the final run Dec was Dec = 0.68arcsecs, which is good for these mounts.

RA was only half as good RA = 1.20arcsecs.

The PA graph in your previous post had the typical rapid jaggednessof these mounts, which IMO is the cause of the jagged RA performance in your final run.

So did you Train the mount's PPEC, what method did you use ?

I noticed that the Guide Assistant run just before your final 5 hour session recommended you carry out a new Calibration, to correct the earlier ones - poor PA and Dec Backlash.

But you didn't.

Not worth guiding for 5 hours until you get the Cal right !

I'm not sure you have been clearing Dec Backlash before Calibrating ?

Michael
Wiltshire UK

[Jed Danyliw]

Hi Michael

This is a non-permanent setup and I have always used the drift align in PHD2 to PA.  I realize that I burned quite a bit of time doing it, but it was a quarter moon night and I wasn't in a huge hurry to get to imaging.  I just wanted a session to run the mount through its paces after adjusting some of the gearing in the RA drive.

I previously used an 80mm/600mm f/7.5 Celestron guide scope, but I wanted to go OAGing for weight reduction, and finer guiding pixel scale.  Are you saying that a wider field of view would be better for plate solving PA?  I see the button in APT but I have never used it.

How can I tell when I have acquired an acceptable calibration?  I always look at the orthogonality of the scatter plot.  What should I be adjusting in order to tweak the next try?  I have been doing this for years now and have struggled with this aspect.

I have done PPEC training in both RA and DEC.  I followed the Meade method, if that makes sense.  ie; fairly high magnification (~12.5mm eyepiece plus 2x barlow) and keep the star centred through 3 runs of the training routine.

I do not clear backlash before calibrating.

Thank you, look forward to chatting about our setups.

jed

[mj.w...@gmail.com]

Hi Jed

OAG is the best option for guiding at your long FL.

But the FOV may be too small for the SharpCap PA routine to work, hence a separate guidescope, just to carry out fast PA's.

Or PoleMaster, this has it's own camera (has to be a QHY) and wide angle lens.

PHD2 will display an error message if the Cal isn't acceptable.

PA of 5arcmins and clearing Dec Backlash before Cal reduces the chances of an Ortho error, and makes the Cal more accurate and more likely to be error-free.

I'm not sure you should PPEC Dec, that's for Alt/Az mode where Alt is continuously tracking -  but your Dec was good, so don't alter !

With the Meade PPEC method you can do an "Update" run after a "Train" run, to further improve the PE.

Michael

Wiltshire UK

[gadget...@att.net]

Saw this post and was interested in the OAG references.  I have a fork mounted Meade 10” LX200GPS all setup on an equatorial wedge.  It is not on a permanent mount.  I have not acquired a newer type of OAG and never have successfully used the old Meade OAG I have had for years.  I tired to set the old Meade OAG up with my StarShoot guide camera, but I have not done it yet.  Did setup how it would look in Stellarium in particular how the OAG mirror might project into the picture frame.  Got that off a YouTube video on how to see if you will have a guide star in the FOV of the OAG.  However, prior to that attempt, I did change out my guide scope to an Orion 50mm Mini Deluxe with a helical focuser using my StarShoot guide camera.  I was able to lighten up the telescope and balance it much better.  My guiding improved as well.  I also did, some time ago, an update on the gears and adjusted them to reduce most all backlash and have done the PEC training.  MeadeMods has videos on gear adjustment.  In PHD2 the other night my Tot: was showing 0.50 and down to around 0.30 most of the night.  As long as I do not have any wind the guiding has been really good and I do not lose as many pictures due to movement.  I have several YouTube videos showing my setup if you are interested in seeing them; https://www.youtube.com/@gadgetmanbowen3081/videos.  I have spent 20-years trying to get my telescope balanced and get better guiding and now I have it, simply by changing out the guide scope which also aided in removing the rear cell Peterson disc weight.  Now my balance is achieved using only two of my three lightest barrel weights.  I know everyone states for my FL, I should use an OAG, but I do not know if I want to spend anymore on this telescope setup now that I have a German Equatorial SkyWatcher EQ6-R Pro that will take a newer Celestron 9.25” SCT.  That telescope maybe a future purchase.  My SkyWatcher guides really well with the 6" SkyWatcher Newtonian on it now.

As for star alignment, I use the Meade’s method.  I tired the PHD2 or was it SharpCap’s method with the Meade and it was very time consuming.  I even contacted Meade about that method, and they stated to use their method.  Soon after, is when I changed out the guide scope, balanced better and got better guiding just using Meade’s polar star alignment and then doing star alignment. 

Hope this helps.

Jerry 

[mj.w...@gmail.com]

Hi Jerry

Well you seem to have got away with guiding with the Orion 50mm Mini Deluxe with it's floppy finderscope attachment methods :->
But I think the 10" has the mirror lock which helps a lot.

"I tired the PHD2 or was it SharpCap’s method with the Meade and it was very time consuming. "

SharpCap is fast, PHD2 does take time.

"As for star alignment, I use the Meade’s method."

Do you mean the Polar Alignment starting in the "Home Position", pointing to the NCP with the scope "upside down" ? Then hoping the Polaris Hour Angle allows the scope to slew to where you can see Polaris in the finder without neck injury ? SharpCap for me !

Michael
Wiltshire UK

[Jed Danyliw]

Hi Michael

So are you saying I should just keep attempting calibrations until no error messages come up?  Or is there more to it?

Another reason for going back to OAG was to eliminate flexture.  

Jed

[mj.w...@gmail.com]

Hi Jed

"attempting calibrations until no error messages come up "  is like trying to pump a tyre up that has a flat.

You'll keep getting "error messages".

You have to fix the problems first, in your case improving PA and clearing backlash.

Michael

Wiltshire UK

[Jed Danyliw]

Michael, 

The error messages are stemming from those factors?  I always assumed that the error messages come from mount problems? 

Jed

[mj.w...@gmail.com]

Hi Jed

The error message comes from PHD2, reacting to out-of-range results from the Cal.

And the out-of-range results may include 

Guide rates too low, or very different,

Poor Othogonality

Too far from Dec = 0 

Probable lots more

And those are mount setup problems.

Michael

Wiltshire UK