Obervation,right or wrong

[dicklaxt]

Not knowing just how things work for sure ,lets talk about a Zoom lens again and the Auto Focus.............#1 you set the varible mm setting manually,and with the focus switch set to auto, depress the shutter button halfway down, the USM kicks in and turns the focus ring until focused.

right or wrong?

[dicklaxt]

I have been kicking around other forums and right is the answer,

dick

[jerryph]

Pressing the shutter button down 1/2 way on most if not all dSLRs will result in the camera focusing the lens for the scene.

Yes, you set your level of zoom yourself, manually.