Originally Posted by Canip
With the term „rocking“, I actually meant that when turning the focus wheel, focusing occurs un-evenly in the two tubes as the bridge pushes and pulls the eyepieces up and down un-evenly (too much play in the mechanics). This is a frequent complaint about cheaper porro binoculars.
Not just the cheapies unfortunately... I have had something similar manifest itself in a Nobilem (not when focusing - but if pressing the binocular too hard against your eyes the bridge can be pushed inwards).