SteveStrummerUK
sometimes the autofocus does tend to hunt around a lot and often fails to find focus (although that's a limit of my camera, not the tubes) so I normally switch over to manual focus.
That's not really a limit of the camera, Steve. It's the nature of macro, and becomes very apparent in handheld situations. Your focal plane is extremely narrow, and the slightest movement translates to a relatively large change.
Auto focus is more of a hindrance here, as it will be forever chasing the focal plane.
Manual focus is definitely the way to go.
By way of example, my Peach blossom was a very challenging shot. Standing outdoors in a light breeze, not only was I moving, but the flower was as well. With auto focus, this would have been a no go. As you've noticed, it all comes down to timing, and snapping the shutter as your subject crosses the focal plane.
Nice shots. I love stuff like this.