Drift alignment necessary with guiding?

[ubertank]

My question is as the title says really. Is it necessary to do any more than a good polar alignment if you are using a guiding system?

I will be using a Synguider in an st80 next time I venture out and would like to step up to 3 minute exposures, but am unsure if it's possible without drift as I've never used a guiding system before.

Thanks guys.

[Bloom]

Yes, it is! Else, if the individual frames last more than about two minutes you will get field rotation. If you use PHD for drift alignment, it is really easy, and won't take you more than 15 minutes.

[mallorcasaint]

I manage 15 min subs without drift aligning so I don't know where you get that from? No image rotation either on an EQ mount guiding.

[Ant]

I do polar align but not drift align and have managed 30 minutes subs with no rotation. I suppose it depends how close you can get without drift aligning...?

[steppenwolf]

It isn't so much a case of drift aligning, more a case of getting an accurate polar alignment - drift alignment gives the most accurate polar alignment so this is the method often suggested for long exposures of deep sky objects.

The NEQ6 that you have has a perfectly good 'circular slide rule' method for getting a pretty good polar alignment and this should be adequate for most purposes.

Failure to get a reasonable polar alignment and then taking long exposure images will result in field rotation.

[johnrt]

I don't drift align either, just use the polar scope on my HEQ5. I image at 900mm with a small frame Atik camera and get 10/15 minute subs no problem.

The only way is to try it, see what happens!

[Bloom]

Well, when I was using my CG5 with its "Polar Alignment" routine, I was always getting field rotation, especially when in high declination. I own a NEQ6 but I never aligned through the polar alignment scope - as soon as I bought it, I started performing drift alignment.

So, if you fellows say that polar alignment with the polar scope is adequate, that's fine, and it settles it, I guess...

[johnrt]

Well, when I was using my CG5 with its "Polar Alignment" routine, I was always getting field rotation, especially when in high declination. I own a NEQ6 but I never aligned through the polar alignment scope - as soon as I bought it, I started performing drift alignment.

So, if you fellows say that polar alignment with the polar scope is adequate, that's fine, and it settles it, I guess...

Alignment via polar scope alone will only suffice if your polar alignment scope is collimated to the axis of your mount, if it's out then you will always be poorly aligned.

[laser_jock99]

I also use the polar scope + 'align the reticule with the Plough' method (to get the right Hour Angle (and thus put the Polaris circle in the right place)). Works for me most of the time. In the observatory I 'should' by rights do a drift alignment but have actually never found it necessary due to the accuracy of the above method.