Canon lenses have different electrical contacts?

[dtrayers]

I have a 300D with the 18-55 kit lens, a 24-85 USM, and a 70-200 f/4 L lens.

I noticed last night that the kit lens and the 24-85 have 7 electrical contacts (a small one, a large one, and 5 small ones). The 70-200 though has ten (a small, a large, then 8 small ones).

The camera only has 7 contacts, matching to the kit and 24-85 lenses.

Why the extra pins on the 70-200? Is there some feature of this lens that's only available on a different camera body?

Here are two pretty poor pics of the lens mounts:

The 24-85:

http://home.comcast.net/~dtrayers/photos/CRW_1209.jpg

The 70-200 f/4 L:

http://home.comcast.net/~dtrayers/photos/CRW_1208.jpg

[dtrayers]

Nevermind, I just figured it out.

It's for the teleconverters. Must have something to do with the max aperture. I looked at the diagram of the 1.4x converter and it has the extra contacts on the lens side, but the 7 contacts on the body side.

The 70-200 f/4 L is designed to be used with a teleconverter. The 24-85 and kit lenses are not.