Shutter Angle refers

Shutter Angle refers 

Shutter Angle refers to an angled mechanical shutter present
in some cameras; it is a hemisphere of a given angle
that rotates on each frame. The angle is its radius
. A typical fi lm shutter is 180 degrees—open half the
time, or 1⁄48 of a second at 24 frames per second.
Electronic shutters are variable but refer to Shutter Angle
as a benchmark; they can operate down in the single digits
or close to a full 360 degrees. After Effects motion blur
goes to 720 degrees simply because sometimes mathematical
accuracy is not the name of the game, and you simply
want more than 360 degrees.
If you don’t know this setting, you can typically nail it by
zooming in and matching background and foreground elements
by eye (Figure 2.17). If your camera report includes
shutter speed, you can calculate the Shutter Angle setting
using the following formula:
shutter speed = 1 / frame rate * (360 / shutter angle)
This isn’t as gnarly as it looks, but if you dislike formulas,
think of it like this: If your camera takes 24 frames per
second, but Shutter Angle is set at 180 degrees, then the

frame is exposed half the time (180/360 = ½) or 1⁄48 of a
second. However, if the shutter speed is 1⁄96 per second with
this frame rate, Shutter Angle should be 90 degrees. A 1⁄1000
per second shutter would have a 9 degree Shutter Angle.
Shutter Phase determines how the shutter opens relative to
the frame, which covers a given fraction of a second beginning
at a given point in time. If the shutter is set to 0, it
opens at that point in time, and the blur appears to extend
forward through the frame, which makes it appear offset.
The default –90 Shutter Phase setting (with a 180° Shutter
Angle) causes half the blur to occur before the frame so
that blur extends in both directions from the current position.
This is how blur appears when taken with a camera,
so a setting that is –50% of Shutter Angle is essential when
you’re adding motion blur to a motion tracked shot. Otherwise,
the track itself appears offset.