Hello guys and girls, as I promised I will be translating some of my material, original written in Portuguese, to English, so here we go with All about Depth of Field.
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So let´s jump right in to the mud!
Learn what depth of field is and how to manipulate it in your favor.
What is depth of field?
Depth of field refers to the range of distance at which a picture appears with acceptable sharpness, or in focus.
It will varies depending on your camera type, apertures used in the lens, the distance of your subject as well as a mixture of all this previous things.
Print size and viewing distance can also influence our perception of depth of field.
This article is designed to provide a better insight and technique for photography, and not bend your mind on what you already know and practice every day.
The depth of field does not change the sharpness of the photo abruptly, but instead a gradual transition occurs.
In fact, everything immediately ahead or behind the focus plane is already beginning to blur – even if it is not perceived by our eyes or by the camera sensor.
Sometimes you will notice that some lenses will have a thin focal plane, and it give you hard times when focusing.
You will experience this phenomenon on lenses with huge apertures, F/1.2 or F/1.4 for instance.
Since there is no critical point of transition between blur areas and in focus areas a more rigorous term called the ‘circle of confusion’ is used to define how much a point needs to be blurred in order to be seen as blurred.
When the circle of confusion becomes perceptible to our eyes we can say that the region is outside the depth of field and at this point no longer acceptably sharp.
The most important thing is to know how to manage this instead of knowing math in the background!
Controlling Depth of Field
Although print size and viewing distance influence how big the circle of confusion appears in our eyes there´s two factors that determine how big the *COC will be.
Aperture and focus distance, or focal length, are the two main factors to keep you attention on.
Larger apertures (smaller F-numbers) and closer focal lengths produce a smaller depth of field.
The following shots keeps the same distance from the focus, but changes in aperture were applied:
In the photos above you can see how the aperture can handle, and much, its depth of field.
Notice that when I close the aperture the brushes of the bottom are getting sharper, in fact I’m increasing the depth of field in that way.
Photos of brushes were taken with a Nikon D5200 and a Nikkor 50mm f1.8G lens. And it is a good test that you can do with your camera and lenses.
Always keep this kind of effect in mind, it can save or destroy or shot.
Depth of field is not the same thing as background blur?
This is the most common misunderstanding among beginning photographers, a confusion between *DOF and blurring backgrounds.
Now, it is true that DOF is a tool we use, and much, to selectively blur parts of an image, to isolate the subject or to create what we call selective focus.
But thinking of DOF as just one way to blur the background is kind of losing some of the sense of things.
Because in fact the depth of field direction is going exactly in the opposite direction of the blur.
After all, the term depth of field does not refer to the parts that are blurred in the image, and yes at acceptable focus distance.
DEPTH OF FIELD (SUBSTANTIVE): THE DISTANCE RANGE IN AN IMAGE WHERE THE FOCUS IS ACCEPTED.
Here is an example where the background blur is used as a tool to isolate the object of interest in the image.