Depth Of Field Adjustment Tutorial Author - Man1c M0g (http://forums.biorust.com/member.php?s=&action=getinfo&userid=1)

With careful planning and good lighting conditions, the subject of a photo can stand out beautifully, and draw the viewer's attention to it immediately.  But what happens when the subject of a photo is less distinct, or the background is simply too intrusive/colorful?   This tutorial describes a very simple method for depth of field adjustment using default Photoshop tools and a little touch of creative vision.
 

Step 1: Open up a stock image in Photoshop of any size and/or format. The best results for this tutorial usually involve large images with a definite subject in focus in the image.  This isn't absolutely essential, of course, but since we are blurring the superfluous details, the end result will look unusual if the entire image lacks sharp focus in any area.

Step 2: Select the Magnetic-Lasso Tool and draw a selection around the focal object in your image.  The Magnetic-Lasso Tool works by detecting edges and placing down control points (the little squares) automatically.  You can place a control point manually by clicking once on the image, and remove the last point by hitting the backspace key (very useful if you sneeze whilst you are mousing around the object). Note:  If you desire even finer control, you can use the Polygon-Lasso Tool, or just the plain old Lasso Tool, although these require a bit more skill!

Step 3: When you have finished drawing the line around your object, click on the first control point to close your selection.  You should now see the so-called  'marching ants' around your object.  For the next step, however, we want to blur the background and not the object, so choose Select > Inverse from the main Photoshop menu to reverse the selection.

Step 4: Now that we have the background selected, we can blur it by selecting Filter > Blur > Gaussian Blur from the main menu.   Just move the 'Radius' slider around until the background blur suits your own individual tastes, and then click OK. Now just lose your selection via Select > Deselect, and admire your results! Note:  Feel free to use the Blur Tool to soften out the edges of your focal object if they are a little too sharp.