In this tutorial we will learn how to adjust the depth of field on a camera
Depth of field is a very important parameter in photography, therefore it is essential to use it well. By mastering the depth of field you will be able to choose to have the background in your photos clear or blurred so that your subject is highlighted. For example, in the main photo of this article the highlighted subjects are the wedding rings.
What is the depth of field?
The depth of field is the distributed area in front of and behind where you focus, also called the area of sharpness. In a photo it corresponds to the distance that appears clear. Everything before and after this part will gradually appear blurred. So the depth of field will always be one third in front of the focal point and therefore two thirds behind the focal point.
- If your entire photo is clean,
the depth of field is deep.
- Is there a lot of blurring in front of and behind your focus?
Then the depth of field is shallow or none.
The opening of the diaphragm
The opening of the diaphragm is the factor that most influences the depth of field.
Here is a tutorial on opening of the diaphragm.
The opening of the diaphragm will then allow you to produce incredible effects on your photos with shutter speed and ISO sensitivity. These are the three most important settings to get a good exposure. Once you master these three parameters, no more photos will be impossible to take.
Let’s continue with a little reminder:
The opening of the diaphragm determines in fact the amount of light that passes through the lens to reach the sensor of your camera.
Thereby the more open the diaphragm, the shallower the DOF. Blurred
But, the more closed the diaphragm, the deeper the DOF. Clean
Low figure f/2.8 = large opening = shallow depth of field, very good for portraits.
High figure f/22 = small opening = deep of field, useful for landscape photos.
As you may have understood, to have nice blurring behind your subjects you will have to open the diaphragm. Moreover this is why lenses with a large opening are very expensive (for the depth of field and brightness they enable).
The focal length of the lens
Then the focal length of the lens is the second factor that influences the depth of field the most. So the longer the focal length, the shallower the depth of field.
Let us sum up:
The shorter the focal length (14mm), the deeper the DOF.
The longer the focal length (600mm), the shallower the DOF.
Distance from the subject
Another factor that affects the DOF is the distance between the camera and the subject. The closer you are to it to focus, the shallower the depth of field. This is exactly why the depth of field is very shallow in macro photography. Conversely, if you have strayed from your subject, the depth of field will be very deep.
It is also for this reason that the depth of field is immense in landscape photography.
Photo edited in Lightroom. [Click here to learn how to use Lightroom.]
For the same focal length the depth of field is deeper with a 24 x 36mm sensor (full frame) than with a 16 x 24mm sensor. Unfortunately this factor cannot be changed. The only thing to do would be to acquire a new camera with a different sensor.
The difference is not huge, but this notion should be taken into account if you are working with two cameras with different sensors.
By combining a large opening, a high magnification, and then by getting as close to your subject as possible you have all the factors to have a blurry background from which the main subject clearly stands out.
To photograph a portrait you want to highlight your subject by blurring the background. So we will take a 300mm zoom lens, and adjust the diaphragm to a large opening, such as /2.8.
For a landscape photo it is completely the opposite, because we want to have the highest number of clear elements on the photo. So this time we will use a wide-angle lens that will give us a very wide panorama, then we will adjust the diaphragm to a small opening, f/16. This is how we will get a beautiful landscape photo.