I was recently creating an animation, I wanted to show how a cine camera’s shutter works. I wanted to show a semi-circle rotating, that is how it works. I started cutting out cardboard and sticking things together and then realised this will be easier in PowerPoint.

What I needed to do was make a semi-circle rotate using the spin animation.

Now there are some useful setting that can be changed to determine how quickly it will spin and to make it start and stop smoothly. Of course there are some other settings too and in this video below I show you how to do that by make three cogs spin together.