I am running Lion on iMac and iPhoto is up to date. my new camera is a sony a6000. The photos show up in the import window, even with an image of the camera, but when I ask iPhoto to import them it comes up with a message saying Unreadable Files - file is in unrecognised format. The photos are RAW but I've never had a problem importing RAW files before. This is what the file is displaying as in the unreadable files window. /Users/SueHewett/Pictures/iPhoto Library/Import/Masters/Roll 1/_DSC2044.ARW
According to Apple's RAW format support page, Sony Alpha ILCE-6000 support was added in Digital Camera RAW Compatibility Update 5.06 released in August 2014. This update requires a minimum of OS X Mountain Lion 10.8.5 with iPhoto version 9.4.3 or later.
I recommend upgrading to the latest OS X version supported by your Mac.