happygolucky Suspended / Banned Messages 3,101 Name Andrew Edit My Images No 10 Sep 2011 #1 On a canon 20D?
neil_g Messages 30,364 Name Neil Edit My Images No 10 Sep 2011 #2 Is is activated when you start focusing so yes.
HoppyUK Messages 23,200 Name Richard Edit My Images No 10 Sep 2011 #3 IS is activated by both the back-button and/or half-press the shutter release.
OP happygolucky Suspended / Banned Messages 3,101 Name Andrew Edit My Images No 12 Sep 2011 #4 Thank you kindly.