Drift aligment error

[alexV]

Hi everyone

I have noticed that when I do drift aligment with Bakyard EOS the star does not go up or down. It actually goes up for a min then down

I thought if there was something bend then it would take same amount of time to go up and down

Takes about a min to go one way the a bit longer to go the other

I have EQ5 with go to

Any help would be great
I will post a print screen later on tonight
Thank you

http://i179.photobucket.com/albums/w...psd9d1021b.jpg

[alexV]

Both the same for altitude and azimuth

[RobF (Rob)]

Maybe re-read that Alex and see if its exactly what you meant to say?

[Geoff45 (Geoff)]

Backlash?

[alistairsam]

Hi Alex,

I haven't tried drift aligning with BEOS although I have it, that sine wave is very strange.
can you tell us where you were pointing. did you have tracking at sidereal on?
Were you guiding?
There usually aren't many bright stars near Dec0 and the Meridian, so its good to use the guide camera in the main scope and plot the drift using phd with guiding disabled.

just to clarify, you need to point at dec 0, meridian for the azimuth correction and E or W at around 25deg max altitude for the Altitude correction.

Cheers
Alistair

[alexV]

Geoff before you mentioned about backlash i was never heard about it.
I had a look in my seeings and it all was set to zero.

I will do research about backlash on the net and see what its all about

Thank you

[alexV]

Alistar i was pointing north and managed to find a dim star to do drift alignment, not sure how many degrees but i know thats where i was told to point.

Same for azimuth it was about 30 degrees

I was not guiding but
Here the settings i had on Synscan: tracking was set to side rale autoguing to 1x

I was also told to try PEC training which i tried tonight and it did not work, but iam not sure if every thing i did was 100% correct although i did follow the manual.

Thank you

[alistairsam]

when you say autoguiding to 1x, did you mean sidereal rate at 1x?
did you have a guide camera and the st4 cable connected?
the idea is that you can keep tracking at sidereal rate, but not use auto guiding to monitor drift.
also remember, you must only look at drift in Dec and not RA. ignore all RA errors for both the meridian star and the East/West star.

Also, don't look at PEC just yet. try and practise drift alignment and get your polar alignment as close as possible. that will make a huge difference with imaging, and with goto's. guiding becomes so much easier.
so a good polar alignment is like a pre requisite.
Alistair

[alexV]

Yes Sidereal was set to 1x

Guide camera was not connected to ST4 because i thought guide camera is of no use to me until my drift alignment is good enough.

My main concern that how can i do drift if star goes up and down.
That's why i was told to do PEC training to see if that will eliminate the problem.

Why do you think i should not do PEC training?

Thank you

[alexV]

Geoff it say in a Synscan manual that default baclash is set to 10' 00" (10 arcmin. and arcsec.).

I have to double check bu i think mine was set all to zero.

How does baclash effects drift alignment.

[alexV]

Geoff why do you think its a baclash?

http://www.celestron.com/c3/support3...articleid=1664

Backlash is play in the drive gears. All telescopes have some backlash, as gears can’t be too tight, preventing the motors from turning. Backlash causes the delay in scope movement when using the direction arrows on the hand control. It’s especially a problem when moving in the direction opposite the scope’s tracking, when the lag before the scope moves can be on the order of 10 seconds if the backlash is bad.

[alistairsam]

were you doing a pec train during that drift alignment?

[alexV]

Before drift aligment

[alistairsam]

If possible, I'd suggest trying again and posting a screenshot.
pls also mention the steps you took.
I don't think PEC applies here because you're looking for drift in Dec, whereas PEC applies primarily to RA tracking errors, and while tracking, Dec isn't used unless you're guiding.
so creating a pec curve won't help with drift aligning, but it will help with guiding. But they usually have to complement each other, I'm not sure if using PEC with ST4 guiding is a good idea because the move commands could cause unpredictable behaviour, unless this is documented in the manual.
issue is this, the guiding software looks at movement and sends correction pulses via the st4 port when it see's drift. but if a PEC curve is loaded in the hand controller or in software, that correct could be over compensated.

so usually, when a curve is loaded via EQASCOM and pulse guiding is used, it knows what the combined result would be before sending the correction command. so they work well.

i'm not familiar with the hand controller PEC, but I'd suggest fixing one issue at a time.

so try using the guide camera in the main scope and using phd. disable guide outputs and turn on sidereal tracking and watch the dec drift in the phd graph.

Cheers

[Steffen]

I can't imagine a mechanical problem with the mount that would cause a star to drift up and down in Dec in the space of a few minutes and with the mount pointing East. To rule it out you could use a reticle eyepiece and watch a star drift, with the mount running stand-alone, just tracking in RA.

If it drifts properly there you know the problem has something to do with the way your electronics are hooked up, or with what the software is doing.

Cheers
Steffen.

[RobF (Rob)]

Certainly a strange one, and would be good to know what happens visually. I'm not familiar with Backyard EOS - is that what you normally use to guide in? Is there any other software that you could use to verify drift. Is there definitely no tracking at all turned on? (another reason to use a different program possibly).

Drift aligning with a camera is a great way to got aligned once you have it sorted, so worth persevering (not that helps much right now )

[alexV]

I have suspecion that it is a ByEOS that playing up like was mentioned here before.

I use to do drift with my Orion auto guider camera connected to my main telescope. Dont remember if i had the same problem or not.

Hope fully next week end if weather permits i will do drift with reticle eyepiece.
If ill menage to get that drift right ill switch back to BYEOS and see if it will show any errors.

If thats not going to work ill document all my steps and post them here.

Is it possible that this Active USB 2.0 Extension Cable Repeater causing that problem. I bought it for my DSLR because original USB cable was to short.

http://www.ebay.com.au/itm/New-16FT-...bd3d2d8&_uhb=1

Thank you

[RobF (Rob)]

I don't think it'd be the repeated Alex - I use 2 all the time with no issues.
Drift aligning by eye can take a long time as you get closer to alignment. Do you have any other software the camera will talk to?

[alexV]

PHD that came with my Orion Auto guider.

[RobF (Rob)]

Perhaps try Phd with guiding off? I use Maxim but someone here will be able to help with phd. Fundamentally just letting star drift with no tracking and monitoring rate of drift off the graph. Would be interesting to see if you still get the up and down (it doesn't make sense though unless something is moving your mount/OTA during the drift run)