Where to place camera on Move Shoot Move Star Tracker for optimal star tracking results
There are two types of star trackers out there, one of which has counterweight(or sometimes called balance weight) attached on the other side of tracker rotational axis , while the other doesn't. MSM Star Tracker is of the latter. Let's call this type unbalanced trackers for short. There are some innate drawbacks that come with unbalanced trackers:
- When the center of mass of the camera goes passes the topmost point during tracking, some inevitable wobble happens due to the free space between the gears inside the tracker and the unbalance setup
- The unbalanced weight of the camera produces a torque on the rotational axis of the tracker which may cause ball heads, mounts or whatever connected to the tracker to unscrew itself from the tracker
- Battery may drain faster than the counterweighted type, as the unbalanced torque from camera exists as a load to the tracker motor
Fortunately with a little tweak in the camera setup all 3 drawbacks would be eliminated and all that's left is the advantage that we buy unbalanced trackers for - compact, superior portability, covering over 95% scenarios of landscape astrophotography.
The tweak is so easy that there is only one thing you will have to make sure - the golden 15° rule. Assume everything hereafter is following proper polar alignment. Now think of a plane which is vertical to ground and contains the tracker's rotational axis. Let 's call it center plane. If we are facing right against to the side with plate, the center plane appears to be the red line in the picture below.
All you need to do before pressing camera shutter is make sure the center of gravity of camera falls into the 15° zone shown between the red and yellow plane in the picture below. Note that if we are facing the tracker side with the plate, the upper side of the yellow plane sits on the right side of the red plane. This is the golden 15° rule.
Here is an example (see the picture below) where the center of gravity of camera falls into the 15° zone.