Free images results:

Knob pictures, stock photos and images


Blue Door Royalty Free Stock Photos
Author: Barsik

Also, here are some commercial RF-licensed images that match your search criteria:  
Door Knob Stock Image
Author: Cphoto
Old Door Knob Stock Photo
Author: Ajn

Explore more commercial options: More Knob Stock Illustrations & Vectors | More Knob Stock Video Footage