Resize All Finder Columns at the Same Time With Keyboard Shortcut
OS X: It’s pretty frustrating to deal with a multi-column window and not be able to resize it correctly for a good view. There is a quick way to resize the crawler columns in unison, and to quickly expand or collapse the view.
Just hold down Shift + Option, then click the column and drag. As you drag to the right, the columns expand. When you drag to the left, they shrink. This is an easy way to get a complete view of the Finder, or otherwise shrink the columns to fit in a smaller window space if you need to.
Easy Mac Hacks: Tips for Customizing the Finder Column View | Mac | A life