How to use an external editor with Photos for OS X
If you're more comfortable in Photoshop, Pixelmator, Acorn, or another image editor, your instinct might immediately be to 'Edit with..."
That way you way you don't have to worry about photo-specific workflows, you can get right down to nudging pixels. Apple's new Photos for OS X, however, doesn't include support for external editors, at least not yet. So, if you really want to move your images out of Photos and into your favorite image editor for Mac, what can you do?
Full story from the iMore Blog...