Autofocus, body or lens? Or both?

[hamlet]

Is autofocus determined by the lens, body or a combination of both?

 

[runnah]

Both. The lens relays the information to the camera body. Then the body transmits the information back to nikon hq where a team of dozens of photo experts analyze the image and remotely make focus adjustments as needed.

 

[hamlet]

Very good.

 

[480sparky]

I'm gonna guess it's the AutoFocus module in the body.

 

[hamlet]

The question just bugged me because my 70-200 isn't autofocusing as fast as i've seen on reviews. This confirms my suspicions as to why that is.

 

[480sparky]

Not all AF modules are the same.

 

[KmH]

Most DSLR auto focus modules are in the bottom of the camera, and use phase-detection AF.

What reviews show a 70-200 lens actually auto focusing so it can be timed?

Autofocus - Wikipedia, the free encyclopedia
Understanding Camera Autofocus
Nikon | Technology | Predictive Focus Tracking System

 

[JoeW]

Most modern DSLR bodies have an autofocus motor. Most modern DSLR lens have an autofocus motor. There are some body exceptions (for instance, the Nikon D3000/D3100 and D5000/D5100 bodies).

Also, if you feel like autofocus is "slow" then there are a range of things to check to determine why this is so. In my experience, the focal point and the available light tend to have the most impact on autofocus speed (when I find a lens is slow with AF).

 

[KmH]

None of Canon's SLR/DSLR cameras have an auto focus motor in the camera body, and haven't had since 1987 when Canon introduced EOS and the EF lens mount.

Nikon sells (literally) boatloads more of their 'compact' entry-level DSLR's that don't have an auto focus motor in the camera, than they sell Nikon DSLR cameras that have an auto focus motor and screw-drive AF system in the camera.

 

[hamlet]

Not all AF modules are the same.

I've set mine on single point af. It takes longer for me to acquire my focus.