Re: AP1100 Newbie Question


Hi Mark

in my experience, that slight offset is normal and results from the more accurate axis positioning from the plate solving that happens with NINA (I use SGP and it's the same). 

Assuming the difference is relatively minor, I would leave it where it's parked (slightly off angle). It just means when you use it the next time, your first plate solve will be more accurate. I don't think there's any harm in re-centering it on the marks, but your first goto/solve will be off by that much. You can experiment on two different nights and see if my notion holds true. 

On Wed, Nov 3, 2021 at 11:50 AM Mark Lamb <lamb_mark@...> wrote:
A couple of weeks ago I received my new AP1100, and I am familiarizing myself with it.  The only other mount I have had is a G11, which has a simple, straight-forward operation, with integrated levels on the RA and Dec Saddle and only 1 Park position, which would be the equivalent of Park 3.  With the G11, the 1st thing I would always do (with G11 parked) is adjust the RA and Dec so that both levels were in the middle.  At this NCP pointing position, I would adjust the rotation of my camera to what I wanted for the night's target, using either the BuckeyeStarGazer's triple camera rotation levels or an angle finder with level.

The AP1100 does not have any built in RA and Dec levels, but has very nice alignment notches at 90deg increments on both RA and Dec.  I leveled my Losmandy FHD tripod (though not dead perfect) and the tripod is on a concrete patio.  The AP1100's single bubble level in totally inside the circle, but not in the dead center.  Polar alignment is done every night, even though the mount has NOT been moved, using a Polemaster.  (Aside: it seems that the night to night variability in PA on the AP1100 is noticeable less than the G11.)  I perfectly align the AP1100's RA and Dec alignment notches (loosen clutches) while at Park 3, and then set my camera's rotation, just like I would with my G11 and its levels.

At the end of the night's imaging run, NINA parks the AP1100 to Park 3.  I notice that the alignment notches are slightly offset.  The next night, I will again perfectly align the AP1100's RA and Dec alignment notches (loosen clutches) while at Park 3 before unparking, and then make sure the camera rotation is correct.

I have notice that the most recent night's are slightly rotated from earlier night's subs by a few degrees.  The earlier subs were taken in a side-by-side arrangement, but the Dec notches were aligned (though 90deg rotated).

I am wondering if I am doing things right.  I assume the slight misalignment of the notches at the end of the night's park is due to pointing corrections with plate-solving.  I have NOT built any APPM models yet.

Should I re-align the notches when parked?  Should this be avoiding during the night's imaging, if parked before the end of imaging?  Should this only be done at the beginning of the night's session?

Is my intuition right that the RA and Dec alignment notches need to be matched at Park 3 for setting proper camera rotation?


Brian Valente

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