Render small portion of scene Shift + B ? Zooms in not renders section?

So I looked around online to see how can I render just one section of my camera view. A lot of pages said to press Shift + B in Camera view (numpad 0). When I do that and draw a box around the section I want to render, it zooms in and changes the perspective on the shot I am trying to render. Is there a setting I need to turn on? I am using the current version of blender on a mac.

Turn off “lock camera to view” and it will stop zooming in on you and just render the portion you select with shift+b.