Question on Max Particle Size

Hello everyone, I'm having some difficulty understanding exactly how the Max Particle Size setting is working (with the current Unity Particle System). My understanding prior to this was exactly as the tool tip says (the size you set equates to how much screen space one particle is allowed occupy).

However, in my screen shots below, my Max Particle Size is 1, yet the camera shows the very large particles occupying at most ~25% of the screen and when I move the camera back, the particles seem to grow.

Any clarification is greatly appreciated.