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Message: <blockquote data-quote="Bob Blaylock" data-source="post: 302153" data-attributes="member: 16749">The concept that you need to understand, [USER=13129]@Rawfocus[/USER], is <a href="http://en.wikipedia.org/wiki/Depth_of_field" target="_blank">depth of field</a>.  To oversimplify, the larger the aperture (the smaller the ƒ-number) the shallower the depth of field will be, and the smaller the aperture (the larger the ƒ-number), the greater the depth of field will be.  Focal length also comes into play.  At the same distance and ƒ-number, a longer lens will have shallower depth of field than a shorter lens.  The 18-55 zoom that came with your camera complicates things further by having an aperture that is not constant with focal length.  At 18mm, the aperture ranges from ƒ3.5 to ƒ22, while at 55mm, it ranges from ƒ5.6 to ƒ36.  <a href="https://play.google.com/store/apps/details?id=jds.dofcalc" target="_blank">Some quick calculations</a> seem to indicate that the effect of focal length is greater than that of the changing aperture on this lens, that is, the depth of field is shallower at 55mm and ƒ5.6 than it is at 18mm and ƒ3.5.  Anyway, you're trying to get shallow depth of field.  You want the subject to be in focus,and the background to be out of focus.  So, using that lens, you want the subject as close as reasonable to the camera, the background as far away as possible, the lens zoomed to as long a focal length as possible, and the aperture open as wide (as small an ƒ-number) as possible.  You'll have to experiment with these parameters yourself, to learn how they relate and how to optimize them for a particular shot.  You might even want to consider investing in a good, high-speed (large aperture) prime lens, if you're serious about pursuing tight depth-of-field shots.  Another principle you might want to investigate is <a href="http://en.wikipedia.org/wiki/Bokeh" target="_blank">bokeh</a>.</blockquote>

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