Out-of-focus vs subject motion blur vs camera shake

[jamesino]

When a picture is slightly blurry, what are some general guidelines for distinguishing between an out-of-focus blur, a subject motion blur and a camera shake blur?

 

[sabbath999]

When a picture is slightly blurry, what are some general guidelines for distinguishing between an out-of-focus blur, a subject motion blur and a camera shake blur?

Out of focus looks "soft" not "blurry". Motion blur is just that... there is obvious motion if you look close but not everything in the frame is blurry if you are standing still and the subject is moving. Camera shake is motion blur of a kind as well.

 

[Copacetic]

Pretty common-sense-ish, really. Out-of-focus blur results when your subject is out of focus, meaning the focus is most likely on something else in the frame. Motion blur results from the subject moving, which will leave a tell-tale trailing blur. Camera shake will be evident by everything in the frame having a slight motion trail.