Mechanical functions behind Camera Zooming

[jmonin]

Hey all, I was wondering if I could ask a quick question for a major work I've got. I haven't been able to find it anywhere online and I'm struggling to grasp the answer, but my question is:

How do the barrels of Camera Lenses physically expand and contract when Lens is turned?

I understand the effects it has on the picture, but I'm just inquiring as to the actual mechanical events that occur when the Lens zooms in and out.

Thanks everyone!

 

[Kenton82]

A classic electronic, or manual zoom lens both work in very similar ways. The basic operation for a 'servo' operated lens uses a small motor that turns the zoom ring, which in turn, moves the inner lens forwards and backwards inside a corkscrew type of barrel. The twisting of the 'corkscrew' barrels run around the inner side of the lens aperture on a gradual incline / decline, thus propelling the inner aperture to move forwards, and backwards with a very smooth motion. The manual version is exactly the same, except it is not powered, or the 'servo' has been switched off.

Hope this helps a little!
K.