Friday, October 28, 2011

Understanding Depth of Field (DOF)

Back to Main Page

NOTE: This chapter provides information which can be useful to all compact point & shoot cameras, but it specifically addresses DOF when using a compact camera macro lens such as Little BigShot or Raynox.

Depth of Field and Closeup Focus 
Closeups are subject to a shallow depth of field, meaning that the camera is limited to how well it can focus from foreground to background (front to rear).
To help demonstrate, with the camera parallel to this scale, we have good focus from left to right and top to bottom.  To the camera, the scale has no depth at this angle; it is flat.

But with the scale at a 45 degree angle to the camera, we introduce front to back depth and reveal the inability of the camera to focus for depth.  We find that focus is lost to the left and right of center, left representing foreground and right representing background.

So, when taking closeups, if your desire is to have the entire subject with good focus, then have the camera parallel to your subject.

But if the desire is to highlight one part of your subject and allow other parts to drift into artistic bokeh, then have the camera at an angle to your subject. 

 How Zoom Effects DOF
In the series of photos below, you will discover that as zoom increases, dof decreases. So, the more you zoom, the more shallow your dof.  The more shallow the dof, the more difficult hand held focus becomes.  Therefore, when you first start out with hand held macros, begin by mastering focus at 2 x, then 4x, then 6x.

 How Aperture Size Effects DOF
Now, for those who have cameras with a manual mode or aperture priority mode, it is possible to extend the dof (make it deeper) by increasing the aperture value.  But, as you will discover from the photos below, increasing the aperture value also increases the exposure time, so when attempting to extend your dof, stabilizing the camera becomes necessary.

In each of the examples below, we can see that when we select a low aperture value (f/stop), that the camera selects a relatively fast shutter speed (exposure time) and the dof is relatively shallow . . . then, when we increase the aperture value to 8.0 (the limit on most compact cameras), the dof at each zoom level is doubled, but the exposure time is increased.

In the near future, I will be adding examples of wildflowers or some other suitable subjects to demonstrate how shallow and deep DOFs play out in actual images.  Check back!

Like my blog?            Like my Facebook Fan Page also!            Beware . . . I Like Back!   

Back to Main Page