The purpose of a lens distance scale?

Hello all,

I was getting acquainted with Depth of field scales, distance scales on older lenses where you can match up the focal length and aperature and you will be able to line them up and see the near and far focuses (dof).

However with Canon's EF lenses what kind of information can I extract other than the distance of the object/plane in focus? It seems without the aid of some calculator or instrument I cannot get some useful information such as DoF or hyperfocal distance etc? Or am I wrong about this?

Basically other than knowing the distance of the object or plane in focus what other data can I get from this?

Thanks

If you were using a manual flash, you would need to know the distance and adjust your power output.

highbarger wrote in post #3653445
If you were using a manual flash, you would need to know the distance and adjust your power output.

Curious for flash photography, I know the 50 f/1.4 does not return distance info to the camera and I'm not sure my Tamron 17-50 2.8 does either. How does my 430EX ETTL II behave in this case?


Thanks

Edit:
I just reread ETTL II, which does not require distance information bt can be used to fine tune the flash output.