<b>Equipment used:

bodies: 2 EOS 20Ds
Lenses: 70-200 f2.8L non IS, 400 f2.8L non IS, 2x extenders

</b>


<img src="http://www.noreduction.com/images/almspir/IMG_6854_resize.jpg">

<img src="http://www.noreduction.com/images/almspir/IMG_6994_resize.jpg">

<img src="http://www.noreduction.com/images/almspir/IMG_7023_resize.jpg">

<img src="http://www.noreduction.com/images/almspir/IMG_7676_resize.jpg">

<img src="http://www.noreduction.com/images/almspir/IMG_7743_resize.jpg">

whats 'no reduction'?

a few friends and I started up noreduction.com

given you were shooting at 1/125 @ 400mm

The name is derived from the use of Artificial Intelligence used to predict the speed and distance of the moving subject. It greatly increases your chance of getting a sharp image when your target is moving.

<b>How does AI Servo work?</b>

There are two key concepts at work.

<i>Predictive autofocusing </i>

As you might imagine, predictive autofocusing happens whenever AI Servo is on and there's a readable subject with predictable movement.


<i>Shutter release control </i>

Shutter release timing is controlled by the photographer for single shots and the first shot in a burst. Shutter release timing is controlled by the camera for subsequent shots in the burst.


You can see AI Servo in action. With the shutter button pressed halfway track the motion of a moving subject with the active focusing point. You should be able to see the lens continuously autofocusing.

So essentially... when you are shooting objects in motion (motorsports, sports)... AI servo will allow the camera to autofocus as the target moves towards you or away.. allowing for clean sharp pictures. But it's not the only thing... in motion shots... keeping your equipment still is another factor. Shooting at 1/125 at 15-16 aperture isn't exactly "fast". I pan with my elbows locked into my side...without the help of a monopod or tripod... in all cases excluding the 400 lense because it's just too damn heavy...

why doesn't it appear you need to compensate for focal length? i.e. why are all the speed shots I've seen @ 1/100 ish no matter what the zoom?

the shutter speed is down to help with the motion effect. Anything too fast.. and you'll freeze the shot...