I've been a PC user, new to mac, with a Macbook Pro running Yosemite.
I've already spent a lot of time googling this topic, and trying things, but nothing seems to "stick."
I set Lightroom's prefs to open the Import dialogue when a card is detected, and went into Image Capture to set it to open Lightroom, and it might work once, but it seems like whenever I insert another card, Image Capture comes up again! It's as though everytime a card is put in with new images, it's treated as a new "device" or something!
(iPhoto was coming up before, I finally deleted that out of frustration, but then it started pulling up Image Capture instead of iPhoto.)
The Lightroom Import dialogue usually comes up in the background, but I have to close Image Capture in the foreground just to keep working - or explain to my assistants not to use the wrong program to import!
This is probably Apple's fault, not Adobe's, but I'm hoping I can find a solution to this annoyance!
iPhoto was coming up before, I finally deleted that out of frustration, but then it started pulling up Image Capture instead of iPhoto.
You might want to try and reinstall iPhoto and then check its preferences, because iPhoto has a setting that controls the default application for cameras.
In iPhoto, choose iPhoto > Preferences, and in the General pane change Connecting Camera Opens… to No Application. That should clear the way for Lightroom to take over when you plug in the camera.
It's unusual and counterintuitive, but Apple puts some default settings in applications, not in the system preferences. Because, similarly, the setting for default web browser is in Safari preferences, and the setting for default mail reader is in Apple Mail preferences. The counterintuitive part is that if you don't want to use one of those Apple applications as the default, the first thing you must not do is delete that application (or you won't be able to change the setting).