PHD gurus wanted

[philjay]

I have been struggling with PHD for ages, well ever since I upgraded to QHY5 actually. I used to use Guidemaster with my Mintron with never a problem, nice tight stars etc. Ive been able to get semi reasonable images with PHD but never tight stars as I used tom but I put up with it. Now Ive been playing with the finder guider its highlighted this more and I want to try and get tight stars with PHD but Im struggling

 

 

Basically Ive tried changing abbressiveness etc and exposure etc and sometimes the graph is nice and flattish but then things start to wander. I beginning to think its mechanical now

 

Heres a few grabs to show whats going on. Its on the CGE mount, re greased last year, Finder guider with QHY5 cam

 

At least one thing came out of these tests, I have nailed my WO AFRIV flattener reducer now, the numbers on the side bare no resemblance to actual element to back end distance, they might as well have not put anything on it at all, typical WO.

 

So any ideas and suggestion gratefully received.

 

 

PS the 2 minute subs taken in the flattish regions gave super tight stars, subs elsewhere on the wanderings gave slightly elongated stars.

[philjay]

Heres a combine of 2 off 2 minute subs showing round stars

[philjay]

And heres a combine of 2 and 6 minute subs showing elongated stars plus its a crop

[glider]

5 things;

 

....Calibration step is 2500, how many steps does it take to train, you want something between say 15 and 25 steps?

....Search area 20, you've seen my post about setting this to 15?

....RA aggression is 10, I have 90 set.

....Camera exposure set low, I use 0.5s if I have a bright enough guide star to use.

....Min motion 0.5, I use 0.15.

 

I think you'll see the drift turn into a sine wave if you leave it long enough, with a cycle of about 6 minutes.

[philjay]

Hi Noel

It only takes about 10 steps to train, its pretty quick, so the 2500 is the max I would imagine.

Yeah Ive gone down to 0.5 exposure in the past and find 1.0 sec gives the better response.

Aggressiveness was at 100 but I tweaked it based on what Steve had found and things smoothed out quite alot compared to what it was.I shall up it a bit more to see what that does, i think i tried 50 then 25 but settled on 10

Im going to try a lower min motion next based on what Craig Stark recommended in a cn thread re finder guiders

I shall try reducing the search area as well ta.

Tvm

[+Graham]

Phil

Fascinated that your RA is wandering.

If you PA is spot on that should not move off the line.

I would also suggest that you rotate the guide camera so it is at 90 degrees to the imaging camera.

Dont ask me why this helps it was something I read and tried and it sorted my guiding out. I can now do 20 mins on my old  EQ5  without a problem.

Lastly if as in the picture the DEC starts to wander which will affect the RA set it on North or South only instead of auto depending on which way it is wandering off to.

Hope it helps.

Edited August 8, 2013 by Graham

[philjay]

Cheers Graham, every bit helpd, I have heard about the 90 degree cam bit before, shall give it a bash

Tvm all

[Guest Tweedledum]

Hi Phil,

 

Don't know if these are of  any help.??.

 

Obviously not

 

 

 

Edited August 11, 2013 by Tweedledum

[philjay]

Hi Damian

 

Sorry haven't been able to get on much over the past 4 days so missed your links, if this has upset, 0530 starts and 1900 finishes since Friday till last night have made it difficult for me to spend much time on here.

[Doc]

It is always important to remember that real life takes precedence over this forum. Sometimes members are very busy and will answer as soon as they have free time, there is no need to take umbrage.

[philjay]

Well the past 2 nights have been very useful for training PHD and myself and I reckon Ive more or less got it now. I have now subs with round stars at last and a graph which settles out to more or less what I used to get with Guidemaster, GM was a bit flatter and stars were very tight because I was guiding at F12 with a 127 Mak   I went the ST80 then the finder guider route to reduce weight and the QHY5 does not work with GM no matter what others say, (it don't work on mine and Ive tried all the drivers and files recommended, nada, zilch. Hence me using PHD

 

So heres the last but one graph from last night, the last graph was quite flat all along, this one shows some messing by me before it started to settle out

 

I shall now transfer these new learned skills to my ST80 guiding and the big Meade frac at F7.5 to see what happens

 

So thanks again for the tips Noel and Graham

[+Ibbo]

that looks much better Phil

 

I would be tempted to pull that aggression down with that good a graph, it may tend to overcorrect

[philjay]

I did Steve and it started to wander, hence I took it back up and it all settled nicely, even better than after this screen grab, RA and Dec behaved nicely with the graphs just having a slight ripple. Subs were good and I was pushing them out to 15 minutes with round stars still then the cloud was wall to wall so I called it a night.

[+Ibbo]

well I would ignore me then

 

yes I had a cloud issue as well

[philjay]

Who can ignore you Steve?

[+Graham]

nice one Phil glad you have it under control

[+RonC]

Phil, can I ask you for a copy of settings please, I'm using a QHY5 and setting it up on a finder guider? 

Tested it tonight but it clouded over !! (again!!)

 

Thanks

Ron

[philjay]

There you go Ron, hope its of use. I guided quite successfully at Kelling with these settings and got quite a good graph when the wind wasn't blowing

 

[glider]

Re.,,,,,,,,,,,,,,, Calibration Steps, bear in mind the f number of your guide scope. I use 2500 for my ST80 f5.

[+RonC]

Thanks Phil (&Glider!) 

[Allan the Plumber]

Just to add to Ron's question about PHD guiding, managed to get everything working last night but noticed on the graph that the RA was tracking fine but it looked like the mount was fighting with the DEC as the blue graph was up and down and sometimes leaping up and below the mid line by more than the 2 boxes as I was shown

 

I also notice from Phil's screen scape that a lot of the parameters where different from the generic one I have!!!

 

would a change to the Max Dec duration help with the wild DEC graph lines? I was managing to get 500 second with a slight elongating of the stars towards the edge of the image and I know a coma corrector will help with this. 

 

I have change the Calibration steps to 2500 as I have a ST80, would Phil's PHD set up be suitable for my mount scope and guide camera set up (think I have something similar to Ron's)

 

Just one last point the only way I could get the camera to talk to the mount was by using the Ascom (late) camera setting. I'm sure at Kelling I selected the camera from the drop down list and then clicked on my mount listed on the mount list 

 

Now when I click on the Ascom (late ) camera and then onto the mount Icon my camera make and model come up there is this right? it worked yesterday but just wanted to check

 

Thanks

Allan

[+Ibbo]

It could be its over compensating if the PA is out a bit or backlash in the gears

 

I run mine slightly heavy at the back end and turn off either North or south let it settle for bit and see if its better.

 

If pa is out n or s it will only need to adjust one way, some imagers deliberately off set PA (N or S) by a small amount to do this

[Allan the Plumber]

It could be its over compensating if the PA is out a bit or backlash in the gears

 

I run mine slightly heavy at the back end and turn off either North or south let it settle for bit and see if its better.

 

If pa is out n or s it will only need to adjust one way, some imagers deliberately off set PA (N or S) by a small amount to do this

Sorry Steve bit thick here

 

What is PA ?  do you mean the weight at the back of the scope ?

 

sorry still new to this

[+RonC]

Polar Alignment Allen..

What about PHD2, is that an improvement??

Edited November 5, 2013 by Ron Clarke

[+Ibbo]

PA = polar alignment

 

and yes I do balance the scope so back end is a bit heavy -not by much