Backfocus

Hi all,

i could only find some things about infinity focus on the BMCC. But i am not sure if that is the same as what i found.
I did my second shoot with the BMCC EF. The first was making a couple of fill shots where i did not zoom.
The last shoot was an interview setting were i needed to zoom out every once in a while.
Zoomed in i was in focus, but as soon as i started to zoom out the subject was out of focus. So it seems the backfocus is not what i am used to with 5d and 7d.
I shot with a canon 24-70mm USM lens. When shooting with the canon 5d i never had this problem.
Is this normal with the BMCC and if not what can i do about it? Since there is no backfocus ring on the lens. Or is this a typical cinema camera thing?

thnx for your reply's!

I´m not sure that that lens is parfocal. I don´t think the back focus issue applies here. In non-parfocal lenses the focus ring breathes a little when you adjust the zoom. Strange you didn´t noticed it before on the 5D.