Letter of the Week: Al Servo

To: is in fact for continuous focus rather than the one that switches between single and continuous.

To:     POP Editor
Subject:        Canon AI Servo Definition

Popular Photography Editor:

Page 44 of your March 2009 issue discusses the purpose of the autofocus mode switch. The article discusses a third mode called "AI Servo" for Canon cameras that autoswitches between single and continuous focus. "AI Servo" is in fact for continuous focus rather than the one that switches between single and continuous. "AI Focus" is Canon's terminology for the mode that switches between the two focus modes.

Michael Cohn
Los Angeles, CA

Oops. That's correct. When do I begin servo-ing my sentence?
—Dan Richards
Senior Editor