Hasselblad and extension tubes

I have a 55 ext tube and how much do you have to compensate when using it?

I also have a 16 and with that one it really doesn't need any compensation.

Thanks,

Kev

all the info you need is in this PDF on the hasselblad website
http://www.hasselblad.se/Archive/doc...on/Closeup.pdf

Thanks, Fintan, that information is most useful to me as well.

ka