Drift Alignment Issues

[E_ri_k (Erik)]

Hi. I have a HEQ 5 with a 1200mm x 245 scope. I am trying to do a drift alignment, but it is frustrating me as I can't seem to get it right. I have followed the "How To" section on this site. I have faced the mount South, using a board to get my East West correct, and calculated the magnetic declination for my area and allowed that.

I have aligned the crosshairs in my eyepiece to match the hand controller.

I know that my latitude is about 37 degrees. I start off with the scale at around 30, and find a star in the West and watch it drift. it drifts South, so I raise the latitude scale and try again. I get pretty close, with the scale at around 35-36 but its taken me a while, and the star has drifted to close to the horizon for me to see properly. So I pick a new star in the West, but now it drifts North, so I lower the altitude bit by bit trying to get it right again. Get close again, but now the scale sits on 29-30?

I have the same problem when adjusting the Azimuth direction. Nothing seems to be consistent?

I don't know what I am doling wrong?

Any help would be appreciated, thanks!

[Poita (Peter)]

Have you had a go at this document?

http://www.iceinspace.com.au/forum/s...t=21167&page=2

and the drift simulator here?
http://www.petesastrophotography.com/

[E_ri_k (Erik)]

I have read the guide on this site, but not the drift sim. The drift sim looks good. Think I might know where I stuffed up. Will try again tonight.
Thanks for the info!

[Poita (Peter)]

If you do work out where you went wrong, please post back and let us all know, it will save me from making the same mistakes.

Well, I'll probably still make them, but at least I will know why.

[RobF (Rob)]

How close do you need to be Erik? Will you be doing long exposure photography?

I could never go back to manual aligning after using a camera on the main scope or guidescope. The beauty of it is you get a rapid quantitive indication of drift.

Some good options to read up on though:
- Polar scope
- Alignmaster
- Drift alignment with camera and PhD or Maxim (or any guiding package that lets you temporarily turn off guiding and monitor drift)

Its a fairly subtle thing doing it manually as you get closer to good alignment.

[E_ri_k (Erik)]

Hey Peter. I think I know where I may have gone wrong (haven't confirmed it yet though) I don't think I picked a star close enough to the equator when checking for drift? Will try again soon. And to answer Rob, I want to pretty close. I am just getting in to astrophotography, so I will use a piggyback system with my DSLR for now, maybe only a few minutes of exposure. But I would like to get into deep space imaging eventually. So I guess it will have to be spot on for that.

There is a website http://www.petesastrophotography.com/ which has a drift alignment simulator. Tried that and seems pretty straight forward.

Will keep playing with it. I will let you know how I go!

[E_ri_k (Erik)]

Got some photos tonight with the camera piggybacked!
Probably nothing special, but I'm pretty happy with them as a first attempt!

The are all about 2 and 3 minute exposures on my DSLR.

[gregbradley]

Hi Erik,

Drift aligning is "easy" and with only 2 possible adjustments "how" can it go wrong?

Well easy.

The usual error is defining drift north, drift south. What does that mean?

You have a scope, you may have a diagonal what is drifting north?

The only way to be sure is to look through the scope and have someone or you do it with a free hand , push the end of your telescope towards the north and see which way the star moves.

You may be surprised and find out you thought it was the other way!!

You know your latitude. That will be the angle of your mount given it is level. So level it first then use a protractor or an iphone app that shows angles. This will have you close.

Now star overhead and watch for 30 seconds for the drift and do your adjustments (have the adjustments written on a piece of paper so you do them right).

Do it again and see if it improved. If it drifts a lot in 30 seconds you are way off so do a larger adjustment. If it drifts just a bit then a smaller adjustment. Ignore other types of drift just north/south.

Get it fairly close then do the 20 degrees above the eastern horizon star. Adjust that until its fairly close.

I usually do it to 120 seconds is stable and that is close enough.

If its a portable setup on concrete or something solid it would pay to mark the spot where the tripod was sitting with tape or paint so next time all you have to do is put the tripod in the same spot and don't change anything with your mount to be setup next time.

Or you attach a laser to the side of your mount and shine it and mark where it hits a wall.

Greg.

[E_ri_k (Erik)]

Thanks for the info Greg. I have got it pretty close now. I can do a 4-5 minute exposure before the stars start to streak. Been reading about guidescopes, and might look into that some day soon. I like the idea of the laser on the mount to allign with a mark on a wall

[PetarB (Petar)]

For a 'first attempt'... I would be pretty happy with that!

[Paduan (Brett)]

Hi Erik i too had a similar issue in the beginning. then when i got it right i would pack it up and go to a dark site and it would all change. so i marked everything, i chiseled small crosses in the concrete and marked the Ra and Dec knobs with paint. now when i go to my dark site for example i know that the marks are about 3 turns different to home it is a good point to start from anyway

[mikerr (Michael)]

Erik, This may or may not be relevant.....

http://www.iceinspace.com.au/forum/s...ad.php?t=73387

My figuring, given the Lattitude in your profile shows that a Digital level should read 52.13833 if laid on your wedge. This fgure is 90 minus your lattitude. I'm not sure what the little built in scale on your mount actually measures.

I hope this doesn't confuse things and if anyone can see that I have the Bull by the whatnots, please correct me.

Michael