Controlling depth of field opens up a whole creative world of possibility that can transform your images. Lets see what depth of field really means .
Depth of field refers to the amount of the image that is in an acceptable level of focus, and is primarily linked to the aperture setting. As a creative tool, it allows the photographer to ‘manipulate’ the frame so that elements can become more or less apparent than they would otherwise appear in reality. For example, a wide aperture will provide a shallow depth of field meaning a very small focal plane and thus small area of the image will appear in focus. The image below was taken with a wide aperture ( f 2.0) hence the depth of field is very shallow and the objects in front and back of the object which has the focus is blurred.
This can be useful in blurring the background detail or any undesirable areas distant from the subject or focal point – such as in sports or action photography. In the image below, the background has been blurred out by using a wide aperture hence the main subject stands out in the image.
By contrast, a small aperture will provide a deeper depth of field that keeps more of the image in focus. While taking the image below a small aperture (f 22) was used hence all objects are clear.
This is useful for keeping the majority, if not all, of the frame sharp – such as in landscape photography. See the image below. Setting the aperture to f 8 or f 11 should give this kind of result wherein every thing is near sharp.
So what factors influence your control over depth of field, how can it be utilised to best effect, and can it be recreated in post production? Let’s take a look…
- Depth of field is the range of sharpness in your image.
- The aperture, or f/stop, you choose controls your depth of field.
In other words:
The f/stop you choose controls the range of sharpness in your image. The point to understand here is that, it does not control what you choose to focus on. It controls the range of sharpness in the area before and after the point you have chosen to focus on.
There are two more aspects which control the depth of field that is, distance of the camera and background from the subject and the focal length of the camera, we will discuss these later.
Look at these images. They were shot at three different apertures and in each image I focused on the face of second doll from the right so you could see how the depth of field would range between the objects in the frame. The first one was shot at f/2.0 and only women is in focus – everything in front of it and behind it is falling into a soft blur.
The next one is shot at f/5.6, and you can see that the other porcelain figures are just starting to come a bit into focus, but the depth of field is still pretty shallow.
The last photo At f/22 are similar, but if you look closely, you can see that the photo taken at f/22 shows the greatest depth of field with all figures almost sharp and in focus.
Achieving all these different looks, is done in camera, by controlling your aperture to create a larger or smaller depth of field. Controlling depth of field is something that takes time to get good at. It is extremely important to learn how to use depth of field because it’s what will make your landscapes look crisp and it will give your portraits the required focus and impact.
Here are two images which explain the concept.
While taking the above image I set the aperture to f 2.8 and moved quite close to the subject hence achieving a shallow depth of field and thus blurring the background. This made the main subject stand out from the rest of the frame.
While taking the above picture I used a small aperture (f 11) there by achieving a large depth of field, thus objects right in the foreground to far distance are clear in the frame.
Aperture : Using a large aperture is a great way to separate your subject from the background. For a shallow depth of field use wide aperture (small f stop number) such as f1.8, f2.8 or f 4. To capture more of a scene use narrow aperture such as f 11 or f22. Prime lenses offering wide apertures such as 50mm f 1.8 or 100mm f 2.8 are best suited to achieve shallow depth of field and are thus ideal for portrait photography.
KEEP IN MIND: The main reason you want to use a shallow depth of field is when you want something to stand out. Use it to isolate the subject so it doesn’t blend in with the foreground or the background of the image. There are two more factors which effect the depth of field. Lets have a look at these.
- Camera-to-subject distance and back ground to subject distance also effect the depth of field. As you move further from the subject you increase depth of field. As you move closer, you decrease it. This means that you will get shallower depth of field by getting as close to the subject as you can.
- Depth of field is also affected by focal length of the lens. Using a wide-angle lens or zooming out increases depth of field. Using a Tele photo lens or zooming in decreases it. If other variables such as aperture and distance from subject stay the same then a longer focal length lens will provide a shallower depth of field and thus blur the back ground more. Try focal lengths between 70 to 100 mm to achieve better Bokeh while shooting portraits.
I hope by now you have a good understanding of depth of field.
To re-capitulate, three factors i.e aperture, distance from the subjects and focal length of the lens effects the depth of field by itself, but even more so in combination. You can get the shallowest depth of field with a lens zoomed in on a nearby subject using a large aperture. You get the greatest depth of field when you are far from a subject, with the lens zoomed to a wide angle, and using a small aperture.
By creative use of depth of field you can create stunning images. In photographing portraits, Use depth of field to blur the back ground and make your subject pop out. In landscape photography, use depth of field to keep entire frame in focus. So that’s it for this lesson. Take care and shoot great photos.