Canon 50D – “AI Servo” Auto Focus Improvements

The auto focus system in the new EOS 50D is definitely faster and more accurate than in previous xxD models, especially in “AI Servo” mode. This mode is great for moving subjects such as birds in flight where the focus distance is constantly changing. In “AI Servo” mode the subject will be focused continuously while the shutter button is held down halfway. The exposure will be set at the moment of capture. Also, when the AF point selection is set to “Automatic”, the camera will first use the center AF point to focus. If the subject moves away from the center AF point, focus tracking will continue as long as the subject is covered by any of the other eight AF points.

In the past the “AI Servo” mode seemed to be a hit or miss proposition but the 50D seems to offer much faster AF speeds and more importantly, better accuracy. The four shots below were taken from a high speed burst of six images. I threw out the first and the last since they were out of focus but these four turned out great. When shooting birds in flight, I’m very pleased anytime I can get better than 50% of my shots where the eye is sharp and with the new EOS 50D my average is going way up!

Great Egret

Great Egret in Flight 1
Copyright © 2009 Jeff Lynch Photography
Shot taken with a Canon 50D hand-held with auto focus set to AI Servo, using an EF 300mm f/4L IS USM + EF 1.4x Extender with image stabilization set to “Mode 2″. Exposed at f/6.7 for 1/500th of a second at ISO 100 on Lexar digital film. All post capture processing was done in Lightroom 2. Click on the image above for a larger version.

Great Egret

Great Egret in Flight 2
Copyright © 2009 Jeff Lynch Photography
Shot taken with a Canon 50D hand-held with auto focus set to AI Servo, using an EF 300mm f/4L IS USM + EF 1.4x Extender with image stabilization set to “Mode 2″. Exposed at f/6.7 for 1/500th of a second at ISO 100 on Lexar digital film. All post capture processing was done in Lightroom 2. Click on the image above for a larger version.

Great Egret

Great Egret in Flight 3
Copyright © 2009 Jeff Lynch Photography
Shot taken with a Canon 50D hand-held with auto focus set to AI Servo, using an EF 300mm f/4L IS USM + EF 1.4x Extender with image stabilization set to “Mode 2″. Exposed at f/6.7 for 1/500th of a second at ISO 100 on Lexar digital film. All post capture processing was done in Lightroom 2. Click on the image above for a larger version.

Great Egret

Great Egret in Flight 4
Copyright © 2009 Jeff Lynch Photography
Shot taken with a Canon 50D hand-held with auto focus set to AI Servo, using an EF 300mm f/4L IS USM + EF 1.4x Extender with image stabilization set to “Mode 2″. Exposed at f/6.7 for 1/500th of a second at ISO 100 on Lexar digital film. All post capture processing was done in Lightroom 2. Click on the image above for a larger version.

7 thoughts on “Canon 50D – “AI Servo” Auto Focus Improvements

  1. John,

    That’s correct. I let the camera decide “IF” my background is far enough away or uncluttered like the sky. If the background is close to the subject this method can fail if the AF system decides to use an AF point which misses the subject.

    My basic rule of thumb is to use “automatic” against the sky or water an use the center point only anywhere else.

    Jeff

  2. Jeff,

    OK, I guess we’re talking the same thing here. In automatic all the 9 points are lit when you select and choose using the joystick. So it seems you’re using automatic mode.

    John

    • Allison,

      Thanks for reading and for your kind words. We’re blessed here in Southeast Texas to have some of the best areas for wintering birds to congregate. A nature photographer’s paradise.

      Jeff

  3. John,

    I’m not sure I understand your question but with the EOS 50D you can set the AF point to automatic (and let the camera decide) or you can choose any of the nine AF points.

    Jeff

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