Won't airdrop from iMac to iphone
imac wont airdrop to iPhone, but automatically sends pics to my sons iPad ( which I don't want)
iMac
Your iMac must be running the latest OS X Yosemite v10.10 for AirDrop to work > Use AirDrop to send files from your Mac to another nearby Mac or iOS device - Apple Support
If you aren't sure which OS X is installed on your Mac, click the Apple menu top left in your screen.
Select: About This Mac from the drop down menu then select the Overview tab.
The version is noted there.