How do I view a webcam image on OS X 10.11
If you just want to see what your webcam is showing:

Open QuickTime Player --&gt; File --&gt; New Movie Recording

It will give the option to record what your webcam is seeing but you don't have to. It will show a video feed from your webcam.

As an alternative to QuickTime Player you can use VLC.  You'll have to download it from VLC's website.

Once installed:

Open VLC --&gt; File --&gt; Open Capture Device --&gt; Tick Video --&gt; Choose your camera for the drop down list --&gt; Click Open