50m Penalties -How do they measure it?

[MalteserMan]

So I was wondering, is there a method that all umpires must use to judge 50 meters when giving a 50m penalty?

I only ask because I was at the Hawthorn/Geelong match and 1 50m penalty (which was soft and resulted in a Geelong goal) was probably only 40 meters while a hawthorn one later in the game seemed to be more like 60 meters...

Sure it may have been perspective but it got me thinking...

[Justin Bieber]

They always estimate. Some better than others ;D.

[CFC 1979]

well they cannot count up to fifty so it must be a guess