Whoompf And Boomf
Lest you think I mean folding in the middle, I hasten to clarify*. The lens parks itself in itself and only comes out to working size when you twist the main barrel. Users of the 1 -series cameras or lenses in the Olympus micro 4/3 range will recognise this as a very effective ploy to reduce the size of the thing for carriage.
The idea has been applied to the 18-55 standard zoom that comes with the smaller cameras. It will be seen on the new D3300 and some of the others, I suspect. If it proves useful, perhaps they will extend the design concept to other longer lenses. Logic tells me that to house concentric lens barrels that add up eventually to a longer focal length requires an increasing diameter in the main ring. Fatter lens - twist it to get longer.
We shall see. Don't know when but will photo it as soon as one gets here.
*All lenses can fold in the middle, but some only do it once...