Hi - So we all know the rule of double the frame rate for exposure for the proper amount of motion blur (180deg rule). So 30fps should be 1/60, 60 fps should be 1/120. 

However, what happens if you film at 60fps but use the footage in a 30fps timeline with the intent of using speed ramps at times? Should I be using 1/60 or 1/120? I've heard different things.

The 180-degree rule is designed for just this kind of situation, and actually makes very little sense the rest of the time and especially at high-FPS playback.

Here's my favourite video explaining this stuff:

(10-Nov-2022, 01:23 PM)Banelle Wrote: The 180-degree rule is designed for just this kind of situation, and actually makes very little sense the rest of the time and especially at high-FPS playback.

Here's my favourite video explaining this stuff:

So if I understood him correctly for 60fps in a 30fps timeline at normal speed you shpuld use 1/60 shutter? However if you slow down the footage by 50% in a 30fps timeline then it should be 1/120. Did I get that right?

If so I usually do 60fps footage in a 30fps timeline at normal speed with occasional speed ramps to 50% speed (usually in a dive or doing an orbit). If my shutter is fixed at 1/60 then technically the motion blur in the slowed down sections will not be quote correct right? Any solutions for that?

Motion blur becomes less apparent the higher the fps. At 60fps I would run the shutter at 360 degrees to maximize blur (1/60th of a second). It still won't compare to the classic 24fps 1/48th of a second blur because the exposure time is longer than at 60fps.

The timeline/playback speed is irrelevant because motion blur happens on a per-frame basis. It's all subjective so why not try a few different settings and see what looks best to you?