metz 20 b-5 / metz 20 bc6

[a giant rat]

Hello helpful folks.

I've got a Bessa R and i want one of these two flashguns , i.e the metz b-5 or the metz bc-6.

http://www.metz.de/en/photo_electronics/mecablitz_20_BC_6.182.html

http://www.metz.de/en/photo_electronics/mecablitz_20_B_5.221.html

And I quote - "The simpler model is the mecablitz 20 B-5 which can only be operated manually; the 20 BC-6 is equipped with 1 tele-computer aperture. "

What is a tele-computered aperture? Is it relevent for a camera such as a bessa-r?

Thanks for the help, I can't find this information on the metz website and I have very limited knowledge about flash. (I put this question here because it seems more about flash than bessa-r, sorry if its the wrong place)