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Astrophotography and Sketching >> Beginning and Intermediate Imaging

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pfile
Post Laureate


Reged: 06/14/09

Re: PHD driving me mad....Help new [Re: pubquiz]
      #5467384 - 10/12/12 08:44 PM

> there is no 1x setting just .3 then .5 then 2x and so on as above which is curious as I suppose it must guide at 1x but there is definately no 1x shown on the settings box

well 2x is too high probably, so maybe stick with 0.5x. i've been able to guide the G11/G2 successfully at 0.5x, though i do have differential flexure, which has pushed me to an OAG.

anyway, i'm confused, i thought you were using a gemini of some kind. but the smaller calibration step may still help you.

it kind of does not make sense that the DEC line drifts so much after you've apparently done a solid polar alignment. to eliminate PhD as the cause, you can go into the brain and click 'disable guide output'. of course, you must have done this when you were checking polar alignment so you know about that.

as pointed out above it could be the dec clutch slowly slipping. you do say you are at the load limits...

finally it could be the case that you simply have differential flexure going on. that won't result in a DEC graph like you see, but if your guiding appears to be perfect and yet your stars are still oval, that's probably the cause.


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Gregk
Carpal Tunnel
*****

Reged: 11/19/06

Loc: San Tan Valley, Az,
Re: PHD driving me mad....Help new [Re: pubquiz]
      #5467669 - 10/13/12 01:57 AM

Quote:

pfile: there is no 1x setting just .3 then .5 then 2x and so on as above which is curious as I suppose it must guide at 1x but there is definately no 1x shown on the settings box

Greg:1)Yes I turned dec guiding back on

2)resist switching is on (have never tried the lowpass filter setting)

3) I didn't recalibrate after as I was on the same star and hadn't moved to a new sky area.

4) just carried on in PHD not5 sure what you mean by re start ...just kept it running but clicked on a off the guide star and started afresh a few times without rebooting PHD.

5) it is balanced well in dec and and RA ...if any bias it is a very little keeping load on the gears.

6) the load is at the top of the G11's limit...I have weighed it and it is just within the limits of the mount...the settings have varied alot as I have tried various ones but as I remember the defaults seemed fine a while ago.

I only got about 10 mins tonight before I gave up with the cloud but dec tracking did seem to be a bit better....hard to be conclusive though as it went total cloud so gave up and came in...off to bed now will try again tomorrow weather permiting.

Much appreciate all the replies and help.....won't let it beat me

Tom




Hello again

Can you tell me what your settings are

min motion
agressivness
Hysteresis
calibration steps in ms
focal length of guide scope

I meant restart PHD after you do the polar by phd
maybe memory or some variable is getting clobbered just guessing though.....The other thing maybe gears or cables
Do you have another guide cable? Never had a G11 so I can't comment on that side of things.. Hope you find the problem


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michael hester
professor emeritus


Reged: 11/28/08

Re: PHD driving me mad....Help new [Re: Gregk]
      #5467994 - 10/13/12 10:22 AM

Heh.... i know what's going on as I had this problem on the Celestron ASCOM drivers.

The direction for short commands is reverse from the direction for long commands.

Edit, the min motion wouldn't solve this but it would filter out some of the unneeded guide commands.

What you can do is set the Mx Dec to 1000, reset to .2, and see if the guide graph error accelerates. If it does then the guide direction changed between calibration and guiding.

Otherwise .2x sidereal at 150ms pulses should do nothing to your guide graph. but seeing as .5 works you shouldn't have any issues from this.

How is PHD talking to the mount?


Edited by michael hester (10/13/12 10:31 AM)


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JoseBorrero
Post Laureate
*****

Reged: 09/04/09

Loc: Puerto Rico Island
Re: PHD driving me mad....Help new [Re: pubquiz]
      #5468181 - 10/13/12 12:00 PM

My suspicion is check for backlash and endplay.

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D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: PHD driving me mad....Help new [Re: JoseBorrero]
      #5469314 - 10/14/12 05:11 AM Attachment (19 downloads)

Looks like I spoke too soon. I just got in from a frustrating session. The mount would not guide again. PHD would loose the guide star in a minute. Graphs tonight did not have the stair step from before. This time the star just went off the screen.

Mount was polar aligned to where there was no motion for 5 minutes. Star use was to the south. I then tried to setup the guider and thing went downhill after that. You can see by the graph that PHD is not doing much.

I replaced the Gemini controller
I replaced the cables going to the motors
I switched the motors
I switched the guider cable
I removed the cover on the DEC worm. Running normally and not loose.
The clutch is very tight and I have a hard time moving the scope by hand so I don't think that it is loose.
Mount is level.


All of the changes above did not fix the issue.

Later I tried to polar alight again and I could not stop the motion in the star I was drift aligning on. Looks like the DEC is not running at the correct speed.

Attached is the graph from tonight. Very quick drop of the star in DEC.

What is next?


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pubquiz
scholastic sledgehammer


Reged: 10/07/04

Loc: Lancashire England
Re: PHD driving me mad....Help new [Re: D_talley]
      #5469496 - 10/14/12 09:59 AM

Hi All

Yikes Dwight some weird dec graphs there!...hope you get it sorted...my dec graph just gradually drops even under guiding.

Had another small go ...clouds again!..last night and got a gradual curve down on dec again.

Double checked the balance again and found it not to be as balanced as I thought.

So today had a free day so I have totally balanced the whole rig perfectly....it was balanced before in certain positions but not others ....now whichever part of the sky I point it and whichever way round it is (I have the C8 and the C100 mounted side by side (the C100 on an ADM rail and rings) and the Merez 72 guide scope on top of the C8 with an ADM rail and rings) it is now PERFECTLY balanced.

I also tightened all screws/bolts and checked the scope rings delrin tripped screws were tight.

The C8's dovetail is bolted straight to the side by side mounting plate with a bolt at the front and a bolt at the back of the dovetail so I also added 2 more bolts in the centre of the dovetail...the threaded holes were there so thought I might as well use them.

So now I am sure everything is solid and as free from diferential flexure as it ever will be....just incase it was this that contributed to the original egg shaped stars problem.

SO now I am ready for the next test of the guiding....will report here and give answers to the requested settings and results ....maybe a while ...depends as always on clear skiesbut will definately report back

Tom


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D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: PHD driving me mad....Help new [Re: pubquiz]
      #5469901 - 10/14/12 02:33 PM

Looking at the two graphs, I can see that it is getting worse. A friend said that the coupler for the motors may be loose which would cause this. I will check that next.

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D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: PHD driving me mad....Help new [Re: D_talley]
      #5476668 - 10/18/12 10:27 AM

I hope you have had some luck with your guiding. I was able to setup in my backyard last night for a hour. Guiding was bad again. I took a look at the Oldham couplier and I marked the worm and coupler to see if there was any slip. Tried to guide in PHD and it failed as before with the DEC line running off of the graph. I then tried to tighten the screws on the Oldham coupliers but did not feel any movement of the screws so don' think I did anything. Also set the guide speed to .8 on the Gemini. Ran another try at guiding and the DEC was off of the graph. Stopped guiding and started again and guiding was perfect!!??? Stopped guiding and then started it again and it was perfect. So now I have no clue as to why. Will try to setup again this weekend and see what the mount has in store for me.

Have you checked your oldham?


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WillCarney
Pooh-Bah
*****

Reged: 10/08/09

Loc: Bloomington, ILL
Re: PHD driving me mad....Help new [Re: D_talley]
      #5476752 - 10/18/12 11:15 AM

I have had a few issues with PHD and using Lodestar or a Orion SSAG. In both cases where it would not work or loose guide stars all the time it was the ASCOM FUBAR. I took ASCOM out then installed it then it worked fine. For some reason my Vista Home laptop screws up ASCOM and it requires a uninstall and reinstall every so often. It had nothing to do with the camera or the PHD program is was ALWAYS the ASCOM gone FUBAR.
William


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pubquiz
scholastic sledgehammer


Reged: 10/07/04

Loc: Lancashire England
Re: PHD driving me mad....Help new [Re: WillCarney]
      #5477270 - 10/18/12 03:42 PM

Hi Dwight

Not tried since my last post...no clear sky...I havn't even heard of an oldham coupler (I don't live too far from Oldham here in the UK though:))

I have checked all mounts etc on the worm and all seem solid etc.

It is the original stainless steel worm though....I beleive the Losmandy upgrade was a brass coloured one...then of course there is the O-vision worm but it's too expensive for me.

Guided ok in the past anyway with this worm.

Will try again now all balance is done on next clear night I am at home.

Keep us updated how you go on.

Tom


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D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: PHD driving me mad....Help new [Re: WillCarney]
      #5477579 - 10/18/12 07:09 PM

Quote:

I have had a few issues with PHD and using Lodestar or a Orion SSAG. In both cases where it would not work or loose guide stars all the time it was the ASCOM FUBAR. I took ASCOM out then installed it then it worked fine. For some reason my Vista Home laptop screws up ASCOM and it requires a uninstall and reinstall every so often. It had nothing to do with the camera or the PHD program is was ALWAYS the ASCOM gone FUBAR.
William




Thanks for the hint. I will do that while I wait for a clear night. However, I had problems trying to polar align the mount because the DEC would not stop moving. I will tear down the mount just to see what is there


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D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: PHD driving me mad....Help new [Re: pubquiz]
      #5477595 - 10/18/12 07:15 PM

Quote:

Hi Dwight

Not tried since my last post...no clear sky...I havn't even heard of an oldham coupler (I don't live too far from Oldham here in the UK though:))

I have checked all mounts etc on the worm and all seem solid etc.

It is the original stainless steel worm though....I beleive the Losmandy upgrade was a brass coloured one...then of course there is the O-vision worm but it's too expensive for me.

Guided ok in the past anyway with this worm.

Will try again now all balance is done on next clear night I am at home.

Keep us updated how you go on.

Tom




My worm is the stainless steel one as well and it has worked fine so far. The Oldham coupler is what connects the motor to the worm. Small nylon and steel looking thing. There are several set screws on it that attaches to the motor shaft and the worm shaft. I had hoped that mine was loose which would cause the problem but I could not find any loose screws. Still wonder why it started working on its own.
We have a clear night scheduled for Saturday but I am getting married on that day. I don't think the bride would like me slipping out to work on the mount during it.


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pubquiz
scholastic sledgehammer


Reged: 10/07/04

Loc: Lancashire England
Re: PHD driving me mad....Help new [Re: D_talley]
      #5483507 - 10/22/12 11:53 AM

Congrats on the wedding Dwight hope all went well

Tom


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D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: PHD driving me mad....Help new [Re: pubquiz]
      #5483608 - 10/22/12 12:50 PM

Quote:

Congrats on the wedding Dwight hope all went well

Tom




Thanks, and I did not have my mind on my telescope


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Ron (Lubbock)
sage


Reged: 08/17/12

Loc: West TX
Re: PHD driving me mad....Help new [Re: D_talley]
      #5484086 - 10/22/12 05:51 PM

Here's a different thought. Perhaps PhD is working fine, but your mount is unresponsive some of the time. You said your mount is loaded near the max. Does it ever get "stuck" momentarily or refuse to move when you are manually adjusting dec.?

One way to find out might be to put a much lighter load on the mount for kicks, and see if PhD magically starts working again. (My apologies if you already tried this and I misunderstood.)


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D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: PHD driving me mad....Help new [Re: Ron (Lubbock)]
      #5489357 - 10/25/12 10:11 PM

Well I had a chance to test guiding tonight just before the clouds rolled in. No problem at all.

The last time I was out I changed the guide rate to .8 and tried to tighten the oldham coupler. Since then it has worked fine.

Tonight I changed the guide rate back to .5 and PHD had no problems guiding at that rate. Looks much better.

So I think that the real problem was there was some play in the oldham coupler. Give your mount a try.


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pubquiz
scholastic sledgehammer


Reged: 10/07/04

Loc: Lancashire England
Re: PHD driving me mad....Help new [Re: D_talley]
      #5491500 - 10/27/12 10:52 AM

Will do Dwight and post results ...hope to have a play tonight.

Tom


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