On the Mac, preferences for what happens when you plug in a camera or a memory card, are controlled by an app called "Image Capture". iPhoto, Lightroom, etc can automatically put preference settings here, but sometimes they do not get done.
Plug in your 550D, then:
- Search Spotlight (apple+spacebar)
for Image Capture. Select it and
- You should see your 550D in
the main screen. Select it.
bottom left, you will see some
options for the 550D: Select the
application you wish to run when the
camera is connected (or import).
TIP #1: If you wish to NOT have anything pop up, you can choose 'No application' to keep iPhoto or other app from opening when you plug in your camera or card
TIP #2: If you want to stop iPhoto from opening when you plug in your iPhone or iPad, follow steps above when your iPhone or iPad is connected and see TIP #1