Lee,
Genuine (but probably stupid) question, but what's focus backlash?
Egrets
You are right to ask. As far as I can tell from years of enquiry this is what the Americans call 'free play' which is the term I use for the defect where you can rock the focus wheel to and fro by a variable distance but the bino doesn't actually change its point of focus. Notice my description took 26 words so its no wonder some cultures reduce it to one or two.
Lee