You can see the twist grove in my image with the copper. Twist zoom has its advantages, but, as someone commented, it would be nicer if they used the whole area for several threads, instead of just one high pitched groove and ridge.
Just like with cars and women, it would be so nice if we could accumulate all the good features in one.
If you really want easy zoom, look at this thread: 3 X D cell X2 Zooming Light @ Tmart . There is one 3 x D and one 3 x AA with power zoom that stops automatically at max. throw and max. flood.