Confused with {"north", "east"} in the context of hand controller buttons

[choochoo_baloo]

I've been reading some more advice on PHD2 guiding refinements. My calibration suggests considerable DEC backlash. I've just read a tip to make the final DEC slew, pre-calibration, in North only to take up this backlash.

Now I don't understand how the cardinal/compass directions of NESW actually map to the often quoted NESW in the frame of reference of a German equatorial mount, since by definition the camera's FOV is rotating with respect to the fixed altitude-azmiuthal coordinates, as we sweep through RA.

In a nutshell: which keypad arrow, and crucially why, do I use to make a North DEC slew?

[ollypenrice]

Just watch the mount as you press the buttons. Begin by setting the scope to point towards Polaris, so counterweights low. The scope is now pointing north. Standing behind it as if intending to observe, make sure that RA and Dec are working as expected, so the up-down arrows on the keypad control Dec and the right-left control RA. They are almost certain to be correct but check anyway.

Because Polaris hardly moves at all in RA (making east-west rather meaningless) it can be a confusing star to use for getting your head round a GEM, so rotate the Dec axis so that the scope points towards the low eastern sky. Now, when you slew the mount by pressing the right hand RA button the mount will do what it does when tracking, only faster. So it will slew from east to west. This confirms that the right hand RA button is the West button. 

If you do this while looking at the mount I think it should make much more sense to you.

Olly

[michael8554]

Just to make it really easy, some scopes have options to reverse the direction the scope moves when an arrow is pressed........!!

Point the scope South and above the horizon.

Press the N arrow, normal would be for the scope to move Up.

If you continued pressing N the scope would eventually  go through the Zenith (directly above your head) and reach the North Celestial Pole (NCP) where Polaris is located very close to, which in the UK is further to the North than the Zenith.

Michael