Is Depth Of Field Affected By Focal Length? A Practical Test

The fact that the depth of field varies depending on focal length seems pretty straightforward, doesn’t it? Matt Granger however says that wide angle lenses don’t necessarily have a smaller depth of field when compared to longer telephoto lenses:

To understand any of this, you have to know what depth of field is: (Yes, this is very basic) Depth of field is basically the depth of your image that is in sharp focus, it is usually about 1/3 in front of your focus and 2/3 behind it.

In his video, Matt conducts a test to prove his point: He takes the same shot with the same framing and only changes the focal length and the position of the camera. The aperture was kept the same – f/2.8 – throughout the shoot. Of course when changing the focal length of your lens you’ll have to physically move the camera if you want your final result to have the same crop.

Here are the results:

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Back to Basics – Depth Of Field

depth_of_fieldAfter discussing exposure in great detail, I would like to turn to a different kind of control – Depth Of Field (A.K.A. DOF). OK. Don’t jump – you are right. Depth Of Field is not a real control, but more of a result of how you used the aperture control.

In simple words Depth of field is the term you use to describe what is inside the focused area of your image and what is left outside of the focused area (and will stay home alone, and eat dry bread and drink stale water. Sorry Jewish mom syndrome…)

As I said before the control that has the most impact on depth of field is aperture. Bigger apertures tend to provide shallower depth of field. That means that if you open a wide aperture (say f/1.8) you will have a narrow location in your image which is focused. If you set your aperture to a small value, say f/22, you will have a huge focused area. The other two controls you can employ to control depth of field are Zoom focal length and camera to object distance. [Read more...]