The tutorial below will show you how to create shallow Depth of Field – DOF, which normally can only be achieved when you shoot with an expensive fast lens, using photoshop.
Step 1: Open your image
Step 2: Select you main focus point of interest in your photo. In my case, I want to have the flower tack sharp and leaving the background blurred. I assume that you’re familiar with image selection using path, channel masking, etc. So I won’t explain it to you..
Step 3: Save you selection, when a selection window popup, give it a name. Thus, you’ll have a new alpha channel in your channel pallete.
Step 4: Load your selection channel by selecting your alpha channel, and clicking on the “load channel selection” as shown on the image below
Step 5: Make a new channel under your selection channel, name it ‘blur’
Step 6: Invert your selection (ctrl+shift+I), then fill it with black-white color gradient as shown below.
Step 7: Load your ‘blur’ channel, then choose RGB channel, and apply lens blur
Step 8: Play around with the lens blur filter. See what comes best with your image.
See also: Photoshop Tutorials