Apple - Stop Image Capture from opening when a new device is connected

Actually, the best way is:

Once Image Capture is open, click the device in the list, then: Bottom left corner of the application, small triangle. There: switch it to "no application".

Done

One solution might be to use Cameras from Flexibits.

Install this preference pane and set "When you connect new cameras:" to "Do nothing" and it should stop your Mac from automatically opening Image Capture when you connect a new device.

Note that Flexibits don't update it anymore, and don't even offer it on their website but in the limited testing I was able to do it does still seem to work. Also since it isn't updated any longer it's a 32-bit preference pane so you'll get that "To use ... preference pane, System Preferences must quite and reopen." when you open it. However you only need to open it once to set the "When you connect new cameras:" option.

You have to open iPhoto, go into iPhoto Preferences and next to Connecting camera opens: select No Application.