Hi Betsy,
The shutter angle is normally 360º for the full exposure over the complete frame duration and 180º is considered as the ‘filmic” version of it. Which has all kind of exceptions of course.
The time that the shutter is open, regulates the distance which an object can draw on the single frame. In this way, it is only a number in a formula. This creates as a result the values of the vector pass (but always straight, per single frame). Which means 50% gray for no movement and 0 or 100% pixel/channel value for the complete maximum movement. As we talk here about a number-game, a simulation to be precise, we need to use the Option>Motion Scale, to adjust that.
If you change these numbers, you practically change the shutter.
Normally thes Motion scale is there to optimize the information on the rendering. The shutter is then adjusted as simulation in the post processing plug in.
There is even in the “Physical Camera” no real shutter (not even simulated), it is just a time based calculation otherwise very short shutter values would lead to a phenomenon that we normally know as “Rolling Shutter”. It is a simulation, even if the results are very nice. The same is true for Vector based data, with the difference that there are no curved vectors. (It would need a higher frame rate and frame blending to come closer to it, but to my knowledge it never really matches. It is a fast way to get these things done. The next big disadvantage of post processing is the inability to get DOF and MB at the same time in a correct way in e.g., AfterEffects. The Physical camera or better the algorithm does this with no problem. Many people like to ignore that point or are not even aware of it. It is as usual a question of Render-time vs Quality.
I think “Motion Detection in Flame” can deliver these things, or http://www.virtualrig-studio.com/ produces software that can create these results , but the price-point is close to an extra “Render Multi-CPU-box”, so not really an option for most of our needs.
Let me know if you have any other question, I like to share information about photography (several decades of experience :o)
Have a great weekend
Sassi