Understanding Depth of Field in Macro Photography
When taking macro photos (closeups), it is helpful to understand something known as depth of field (dof), and how it effects your macro images. There are times when a shallow dof enhances your image, and there are times when it is unintended or undesired. This thread hopes to demonstrate what is meant by the term dof, what it is, and how to use it or avoid it, dependent upon your particular desire.
At close range, cameras and lenses have a limited ability to focus in the Z axis (front to rear). So if you desire good focus across the entire surface of your subject, then it is best to have the camera perpendicular to (square with) the part of your subject you wish to display.
In this first photo, the camera is perpendicular with the scale, the camera is in macro mode and positioned 2 inches away from the scale. We find a fairly good focus all the way across the image, except for some fuzziness at the extreme left and right edges of the frame. (this is common)
If, however, we have the camera at a 45 degree angle to the scale, suddenly we find that the focus across the scale is limited to an area of about an inch. So, the depth of field (which is probably better defined as the depth of focus) is about one inch.
Now, to make matters worse (or shall I say "more challenging"), if you add a macro lens to your compact camera, as you magnify the view, you decrease the depth of field. Here is a macro lens image of the scale, again from 2" away, but as you can see the scale is greatly magnified by the macro lens. Even so, the camera is perpendicular to the scale and we have a fairly good focus across the entire frame.
But when we have the camera at a 45 degree angle to the scale using the macro lens, we find that the depth of focus is only about 1/4"
When taking macro photos (closeups), it is helpful to understand something known as depth of field (dof), and how it effects your macro images. There are times when a shallow dof enhances your image, and there are times when it is unintended or undesired. This thread hopes to demonstrate what is meant by the term dof, what it is, and how to use it or avoid it, dependent upon your particular desire.
At close range, cameras and lenses have a limited ability to focus in the Z axis (front to rear). So if you desire good focus across the entire surface of your subject, then it is best to have the camera perpendicular to (square with) the part of your subject you wish to display.
In this first photo, the camera is perpendicular with the scale, the camera is in macro mode and positioned 2 inches away from the scale. We find a fairly good focus all the way across the image, except for some fuzziness at the extreme left and right edges of the frame. (this is common)
If, however, we have the camera at a 45 degree angle to the scale, suddenly we find that the focus across the scale is limited to an area of about an inch. So, the depth of field (which is probably better defined as the depth of focus) is about one inch.
Now, to make matters worse (or shall I say "more challenging"), if you add a macro lens to your compact camera, as you magnify the view, you decrease the depth of field. Here is a macro lens image of the scale, again from 2" away, but as you can see the scale is greatly magnified by the macro lens. Even so, the camera is perpendicular to the scale and we have a fairly good focus across the entire frame.
But when we have the camera at a 45 degree angle to the scale using the macro lens, we find that the depth of focus is only about 1/4"
To help reinforce what we've learned thus far, I will use macro lens images of a yellow jacket. When the body of the bee is aligned left to right, the camera has no trouble providing a good focus along the entire length of the subject. That's because his body at this angle has little depth front to rear.
The images of the bee were captured using a Canon Powershot. They came straight out of the camera (SOOC) and were not cropped to make them appear larger. You might be asking yourself how a point & shoot can get such great macros. Well, I cheated. The camera had a P&S macro lens attached. If you're interested in cheating with your camera, here's the link: Little BigShot.
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But when we rotate the bee 90 degrees, we discover that while his face and thorax are nicely in focus, his abdomen drifts into blur. That's because the DOF at this magnification is 1/4" and the bee is 3/4" long.
So, the angle of your camera relative to your subject in macro photography controls your depth of field and focus. It is to be noted that out-of-focus regions (which are known as the bokeh) are not always to be avoided. Bokeh can help accentuate the in-focus regions. It's really a matter of what you're trying to achieve photographically, and this post helps you understand how to use or minimize the shallow DOF associated with macro imaging.
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