Drift Alignment Problems?

[Ronny Kaplanian]

Hi Everyone,

I am in Perth Australia and I have purchased a Celestron 9.25 CPC GPS Scope a year ago, I decided to venture into Astro-Photography and it has been a huge learning curve. I have now mastered the Drift Alignment method after many sleepless nights.

After successfully completing the first R.A Drift method when the Scope is facing the Meridian I then go to a Star in the East or West close to the Horizon and not too far from the Celestial equator, I then position the Star in the middle of the Retic Cross hairs and for some very odd reason the Star drifts in R.A not DEC for a few minutes then everything is OK, in other words the Star does not move up or down just keeps on shifting downwards Parallel to the Horizontal line, After a few minutes of constantly moving the Star to the CENTRE it stabilizes and everything then seems OK. Thinking my first drift alignment was out I went back to the Meridian but everything was fine I called the supplier and he could not answer me. if anyone out there can hear me please help so I can figure out what is happening here, the Supplier said it could not be Backlash as taking 3-4 minutes to stabilize makes no sense with the Backlash method. Of course I have a Wedge equipped on the Stand.I hope to hear from you soon.

Regards

Ronny Kaplanian
Perth

[Blue Skies]

Well, dead silence from the membership is usually a sign that no one knows the answer. However seeing how it is Christmas and people may be elsewhere at the moment patience is recommended.

If you get no answer here I would recommend reposting this question down in the Equipment section.

My thoughts are that perhaps its just a quirk of you scope you need to work with - as you say it settles down eventually, although several minutes does sound too long for simple backlash.

[leinad]

I experienced the same thing Ronny with my GEM(EQ6).
When drifting on Eastern horizon(from memory), the star would not drift N or S, though it would drift slowly East. After a few minutes making a coffee and returning it stopped drifting East and appeared to now be well aligned, not drifting NS or EW.

I could only think that this was the RA speed building up to match the weight balancing of the scope. Have you tried adjusting the tracking speed? Im going to try this tonight if I see the same again.

Im with you on this one. Have no idea currently what causes it.

[Ronny Kaplanian]

Thank you for all your help here, I am glad I joined the Forum as in Perth we are quite remote. I can only adjust the Rate speed manually thru my controller to move quicker to objects or when aligning the object in my scope, but i do not understand how this will affect the Star shift as surely the Scope will be moving at the same rate to the sky. This is a new Scope, only used a few times and I take good care of it so I hope to God it has nothing to do with my Drives. let me know how things go with your observations and I am gratefull for any input into this matter. thanks

Ronny

[leinad]

Hi Ronny, Hopefully someone here with experience can shed more light on this. The same thing happened tonight where there was slight drifting E/W but then it stopped. Sometimes over 15 mins it would drift slightly E then W.
I can only put it down to weight balance on the gears and backlash. It happened sometimes, other times it didnt occur. :sadeyes:
Im sure theres a simple explanation for it.

[bmitchell82]

yeah dan, i think your onto it, I think we might have to have a Perth eq6 owners night :D I just got the go ahead by the minister of war and finance last night to go and pick one up :D YEOW. so a few tube rings and what not :D. though ill be running without camera for a while untill i get the funds.

[Screwdriverone]

Hey Guys,

Just had a thought, wouldnt this be caused by the PEC? The Period Error Correction kicking in or stabilising the scope?

After a while the mount sort of "syncs" itself up based on orientation and balance/load and this is whats causing the delayed fix? When the tube is pointed at extreme angles, ie when drift aligning, it operates and "feels" different as to when the scope is finished and parked after drift aligning and perhaps the CPU has to "relearn" based on the new orientation etc?

Just a thought, but keep in mind most of these higher end scopes/mounts yell from the mountain tops that they have Periodic Error Correction, and this is what it sounds like is happening......

Could be wrong.....or I could be right?

Chris

[bmitchell82]

ITS ALL HEAR SAY AND HERICY... BURN THE WITCH AT THE STAKE :D who knows ay, all im worried about is that when i do the drift alignment and polar alignment and wind alignment and focus alignment and collmination allignment :D that its well and truely aligned and works :D yay if i have to go and make a cuppa or do something else while the jesus box figures it all out then im cool with that, because i know this isn't a Losmundy or vixen mount. Now if i had paid for a losmundy or vixen and it was still doing the funky chicken on me ide be demanding some answers from the people that had built it on why.:rolleyes:

[Screwdriverone]

Did ya get ya EQ6 yet? Brendan?

That sounded like rant from a man with too much money and no mount to spend it on.....

Chris :)

[bmitchell82]

now that i have "rubbed one out" im all good. :D 20 bucks to have it delivered to the premisis of housing. Yeow. too bad i will definately have to wait to get the camera now :D but it will be good getting everything all sorted out plus i can use a bit of gear that i have access to.

They apparently have 3 left at that price. :D anybody wants/needs a EQ6Pro GET CRACKALAKING.

Nope i don't have much money to spend, just the point is that im working full time at the moment thank god for uni breaks and the miss's knows how much i enjoy this hobby + i want to get into photography so... while the going is still good get it :D

[leinad]

Nice! :2thumbs:



I have PEC turned off on the controller; never tried with it on actually.. With more weight on the mount last night, I didnt notice any of the E/W mystery drift as much as before with the refractor/s. It only occurs in RA when slewing E/W. Im thinking the mount continues slewing slightly( like the kepad button is stuck) because it needs to accommodate the weight inbalance?
I do notice slewing is a little slow to start up at a set rate speed when theres a bit of weight at a certain RA/DEC angle, so perhaps it is becuase of that the slew will continue on a small bit. My tracking speed was 0.5x from memory?

[GrampianStars]

G'day Ronny
:welcome:
Nice Scope by the way :thumbsup:
try here:- http://groups.yahoo.com/group/C9-25?v=1&t=search&ch=web&pub=groups&sec=group&slk=1
Ahh Drift Allign :rolleyes:
Balance with slight load on East Fork, keeps gears meshed
When drifting scope in RA IGNORE changes in DEC
When drifting scope in DEC IGNORE changes in RA
Drift method:- (1) pick a Star facing North on the Meridian and on the Celestial equator (2) pick a Star in the East at least 45 deg above the Horizon and on the Celestial equator,
You might have to do this back and forth a coupl'a times as you get closer to aligned.
you also need to train the drive RA and DEC
The slight star up/down movement is PE, where the worm is slightly out of round.
Unfortunately Live with it unless your scope has PEC and you train out the PE

[bmitchell82]

Does the eq6 run PEC? I know with the meade it has PEC that you can train the drives. and for a start of every session that i run with it i train the RA and DEC by using the hex head of a sign about 200 meters away and running with a 9mm Rectical though a 2x barlow. :)

Though i have never trained the drives in PEC via keeping it tracking onto a star untill the worm has moved though a whole revoloution (about 15- 20 min tracking) in each Dec and RA

It would be great if the mount had this option because i would be using it knowing what i know now.!


and yes Dan, i was a bit stoked when she said those magical words, "well are you going to buy it"

[leinad]

Yeah it has PEC. Though I havnt really tried it yet; dont know how it works; and its benefits with guiding and without guiding.

Thats great. When do you pick it up? Does the seller have rings you can grab also on the cheap?

[bmitchell82]

PEC is a good thing, it basically remembers all the inaccuracys of the worm gear drive. the more you train it the better it is at controlling the PEC.

I should be delivered mid next week im hoping. We should organize a day to head out and do some observing :D

Im not sure that he has rings, but im going to look at getting a set made up specifically for my scope. you know what im like with all my little mods :D Making life easier not harder :D

[Ian Robinson]

You got that fork on wedge ? sorryt just noticed you said you do.

How rigidly is the mirror supported in the OTA ?

[bmitchell82]

No ian the fork isn't mounted on a super wedge yet, though this is needed before it can do anything decent, either that or a field de rotation unit on the back.

As for the meade forks i do not rate them at all i belive they are actually quite poor at holding the ota as for a tiny breeze sends vibrations right though. Fine for visual but for photography pffft. unless you have them well protected from wind and vibration!

Other than that they are optically nice!