The depth of field in an image is how much of the picture is in focus (area of image in focus). Beginners would want the entire image in focus, and even though that is often the case. Sometimes it’s better to reduce the depth of field in a scene and make the background soft and blurry.
If you own a DSLR ,you should definitely start experimenting with your aperture settings since it’s one of the most useful tools in a photographer’s arsenal. If you not familiar with Aperture, I would suggest you to read it before reading this article.
What is a depth of field?
It controls one of the most important creative decisions photographers make because they can focus viewers’ attention at a certain region on an image. This is by choosing how much depth of field to have in your shot.
In a frame it is measured around the point of focus. So when you choose your focus, it extends from about an inch of the focus to an inch, or so, behind the focus.
How does depth of field work?
You should know that aperture is one of the factors that controls the depth of field. By changing the aperture settings on your camera, you could control the depth of field. Same as your eyes, a camera lens has an iris (opening or a hole) inside that controls the light reaching the sensor. By changing the aperture, you control the size of this hole A scale of f-stops represents the size of the aperture.
The scale is as follows: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22.
The rule of thumb to understand aperture and depth of field is simple:
- the larger the aperture, the shallower your depth of field is, which means that a smaller portion of your image would be in focus, and vice versa.
f-number denotes aperture size. The smaller the number is, the larger the aperture would be. Setting your aperture to f 2.8 will give shallower depth of field (less area in focus. Most of the image is blurry or soft) than setting it to f 11. You can remember this by connecting a small number to the small depth of field.
How do you control the aperture settings?
To control the depth of field, you must learn to work with aperture settings.
To change a lens’ aperture, you need to have a camera with an aperture priority or manual mode. Most cameras with aperture priority will have a manual mode also.
The mode selector dial on a camera indicates the Aperture priority mode as an A ( except Canon cameras where it’s Av). When the camera is in aperture priority mode, you can choose the aperture you want and the camera will automatically selects a corresponding shutter speed for a given exposure. This is why it is a semi-automatic mode. You may use your camera’s manual on manual and semi-automatic modes and to use the aperture priority mode itself. Please read our article on aperture priority mode for a complete guide.
Now, if you have a camera that doesn’t provide a mechanism for aperture control, you won’t be able to choose a certain depth of field. Nowadays all SLRs have priority and manual modes as same as Micro Four Thirds cameras and some advanced point and shoot cameras like Panasonic Lumix LX3 and Canon Power Shot S90. Still, a camera with a smaller sensor has an essentially deeper depth of field. So it’s difficult to achieve an extremely shallow depth of field even with the best point and shoot camera.
[Bonus tip: If you want to get shallow area of focus with an automatic camera (point and shoot or mobile phones), switch to macro mode and get as close as possible. One of the factors that affects the depth of field is the distance between the subject and the sensor, so getting closer to subject will bring less area in focus. In macro mode, the camera automatically switch to wide apertures, which makes the field shallow]
How to choose the right aperture?
When you can control aperture, the next step is to figure out how much area of focus you want in your photo. You should remember that depth of field depends on what kind of photo you’re taking. In a portrait, for example, it’s preferred to have a shallow depth of field so that the focus is on the subject’s (person’s) face.
Rule of thumb: Shallow depth of field is good if you need a subject stand out from a busy background, like in street, event shooting etc. Use a small f-number for this. On the other hand, there are situations where you’ll want to have a deep depth of field. For example, landscape images can turn out better when everything is in focus, and that’s why you would want a more area in focus. To ensure this, you should choose a small aperture (a larger f-number).
Other situations that benefit from the deep depth of field are street photography, some still-life photography, and any shot where you need to see both foreground and background details really.Images of large areas with great detail in every part of the picture use the landscape photo tradition. To attain such detail, you need deep depth of field. For example, if you’re taking a picture of something you wish to sell online you want every part of that object is in focus; you need deep depth of field.
Every lens has a set aperture range. Some lenses can open to a wider aperture than others (fast lenses). Your lens should list its aperture range on the ring on the front of the camera. For example, Canon EF-S 18–55mm lens f/3.5–5.6. This means the lens has the smallest f-number (or f-stop) it can go is f3.5 at 18mm and f5.6 at 55mm.
Tips for shooting shallow depth of field
If you have a fast lens – a lens that can open up very wide (wider than f3.5)- you should think about how shallow the focus is. If you open it up to its largest aperture it might be challenging for you to stay in focus. This would make your background go too soft and would make it difficult to keep the right part of your image in focus.
Other than controlling the depth of field with aperture setting, another crucial factor to achieve a shallow depth of field is camera position. Even though you might have selected a wide aperture, if nothing visible in the background you could not see if the image has a shallow area of focus. Thus the area of focus in an image depends on the size of the objects in the background.
Tips for shooting in deep depth of field
As I said before, in landscapes shots, you’ll prefer to choose a deep depth of field. Now, there are some important things to remember to increase the area of focus.
- Even though it may seem logical to just dial in the largest f-number possible, it is not practical. The smaller the aperture size is, more the chances are your photo will suffer an optical effect called diffraction, which reduces sharpness in your image. So, if you’re shooting a landscape and select f/22 to ensure deep depth of field, your image will probably end up soft because of the diffraction problems brought by your small aperture choice.
- Depth of field is on your point of focus with some of the range in front and some in the back. When you shoot a landscape by focusing on the horizon some of the focus will fall behind the horizon. Thus, you could not use your depth of field properly, and your foreground could end up out of focus.
Rule of thumb: Focus about one-third of the way back from the horizon ( hyper-focal distance). By doing this, you cover more of the foreground in your depth of field range. Even though there are much more refined ways to calculate your depth of field and focus distance, a rule of thumb is a great place for you to start.
Another tip to attain a good depth of field is focus bracketing. You should bracket your focus until you learn to precisely judge your distance. Try to shoot a series of frames focusing on different distances. If you do that, there are better chances that one of the images will result in proper focus.
The depth of field is by far the most important tool that helps your photos stand out. By using it you can avoid busy backgrounds, or make sure that everything in your photo is sharp. Next time you look at some photos observe the area of focus.
While shooting you may discover that your lens or your point-and-shoot camera can’t go as shallow depth of field as you would want. In that case, you should definitely get yourself some new equipment that can satisfy your needs. If you’re serious about your photos turning the best way possible then you should do everything that’s in your power to make it happen.
Other than that, the best way to master depth of field control is practice and experimenting. Just go and shoot some photos, relax, have fun, play with the settings, and explore your options.
Photos credits: http://maxpixel.freegreatpicture.com/