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)
Camera held perpendicular to object
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.
Camera held at 45 degree angle to object
If you use Little BigShot macro lens, 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.
Macro lens image of the scale
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″
Camera at a 45 degree angle to the oject using the macro lens
So, as you can see, when you take macro images of your items, whether you are in macro mode, or using a macro lens, have your camera perpendicular to your item for best focus across the frame.
Thank you for this excellent article David.
You have explained the concept brilliantly and the little ruler illustrates your points perfectly. I must admit, I knew that having my camera at an angle to the object gave me more perspective, but never really cognitively linked that to dof, although seeing your little rulers made for me an “ah ha” moment!
Excellent explanation. That makes everything very clear. With some compact cameras you are not always able to see the focus so clearly as you can with an SLR so getting the angle right is a huge step in the right direction.