30D & Auto Focusing

[dgore]

I just opened my XMAS present. I upgrdaded from the original Digital Rebel to a 30D. One thing I noticed right off the bat which I have never seen mentioned is the speed of the AUTOFOCUS. I always thought this was up to the lens but the 30D definitely makes a difference over the Rebel. Definitely worth the upgrade. I am using a Tamron 24-135 lens and it is working better than ever before.

 

[Big Mike]

The motor that actually moves focus elements is in the lens...but the autofocus sensors and 'brains' are in the camera...so yes, higher end cameras often do focus faster than lower level cameras.

The 30D, in fact, has a cross type AF sensor in the middle focus point...but it's only utilized when you have a lens attached with a maximum aperture of F2.8 or faster. A cross type sensor is more sensitive than the regular AF sensor points.

That being said, because the focus motor is in the lens. Better lenses do make focusing even better...faster and quieter. For Canon, lenses with USM in the title, are the good one.

 

[markc]

There are two kinds of USM, just to make things even more tricky. The really good ones are ring motors, so I wouldn't go just by the USM label.