I recently stepped up from the Z6 and bought a Z8. The Z8 has breathed new life into my focus lenses because of it's extremely fast 20fps. I can simply rack focus back and forth while shooting and choose the focused image later on. I really like my older CONTAX lenses for portraiture, but would never have used them on the Z6 for anything where focus was critical. Now on the Z8 I feel comfortable shooting portrait sessions with them.