2x converter for Hasselblad

Hi,

I just finished putting together a Hasselblad 500cm setup and loving the camera so far. I have been looking at getting a 2x converter for the 80mm C lens to give me a poor mans 150mm.

Has anyone gone this route and if you have how was the results? I am looking a the Vivitar or Kenko 2x converters.

Thanks!

Vivitar was fine for me.

I was really amazed at the quality the Kenko gave me with a couple of different foical lengths. It did a great job on a 250, and a 150, never really used it on the 80, but am sure it would be a good match. A bit dark to focus thru, but the results were very good. When Hassy stuff was commanding very high prices, that was the one item I thought of as a great value in the system.