Q&A: How do I create motion blur

I want to create an action movie-style scene with two guys fighting. I could use a slow shutter speed to capture motion blur, but there’s a danger that the rest of the shot will look blurred too. I’d like most of the shot to look sharp, but want selective motion blur on the fighters to create a sense of movement. What’s the best way to achieve this effect?
Dan Johnston

The following techniques will enable you to add as much blur as you like to any section of the shot, so you can achieve a perfect balance between motion blur and image sharpness.

01: Fight!
Here’s our source file. It was taken with a high shutter speed to freeze the action. There’s some natural motion blur on the foreground fighter’s fist which we can use as a reference when creating digital motion blur. (No models were harmed in this shoot!)

02: Make a selection
Grab the Freehand Lasso and set Feather to 11px. Draw a rough selection around the area you want to add blur to. Hit Cmd/Ctrl+J to copy the selection and paste it to a new layer. Target this layer in the Layers palette.

03: Ker-pow!
In Filter>Blur> Radial Blur, set Amount to 30. Set Blur Method to Zoom to give depth and perspective. Set Quality to Good. Move the Blur Centre so the blur matches the actor’s movement/position. Hit OK. Lower the blur layer’s opacity a tad.