Understanding Depth Of Field (DoF)

One of the most important skills in the Photography world is understanding Depth Of Field and how it works. In short, Depth of field is generally a make up or a break up of your images. The wrong depth of field and your images can come out looking completely boring, plain, just not interesting. The right depth of field can break that barrier and make your subject look a lot more interesting, help with the focus on the subject, and make the general scenery of the image look a lot more appeasing. Getting the right depth of field doesn’t take a professional camera at all, this is something that can be achieved even on the most basic of mobile phones.

You can adjust depth of field generally by what aperture you use on your camera (If you use one, or modern phones), the angle in which you take your image, the distance of your subject in the image to the camera, focal length and so on. Every image has a depth of field, it’s how you use it that makes the difference.

For a landscape shot, you’re going to want a large depth of field, meaning, you’re going to want most, if not all of the image in focus. Having a blurred distance and a sharp mountain will just look… broke? But for subjects for example, I focus a lot on animal photography, you’re going to want to have a shorter depth of field, meaning that the subject you like is in focus, the animal, and it’s surroundings are more blurry. This helps draw your attention on the subject itself and not the focus on the background of the image. Scientifically known as the circle of confusion.

I will move onto circle confusion in a later post. But in short, it affects the sharpness of an image. In camera settings, for example, f/22 would give a crisp sharp image where everything is pretty much in focus, and this uses a narrow spot of light. This is usually better used on landscape photography as previously mentioned, but would not be beneficial in low light as you may need longer shutter speeds in order to see the object, as the image could come out too dark. f/2.8 would allow in more light, a larger circle of confusion, but also more background blur. This would be more beneficial on portrait, object or animal photography as it helps you focus on the main subject. But areas of the image wont be as sharp, depending on what your focal length is.

For example, the shot above I took on my EOS 90D using a Canon 50mm f/1.8 USM II Lens, but I actually used f/7.1 on this as, as you can see in the below image, f/1.8 actually makes too much of the image blurry, as shown below. Same angle, seconds apart, different aperture. The images actual focal point is the dogs nose. However in the image above because the focal lens used a smaller circle of light, the damage? For the same light to be brought in the image had to use an ISO of 6400 at 1/30th of a second, whereas for a larger circle of light, whilst more of the image is blurry, there was enough light entering the sensor meaning the ISO was 1250 at 1/100th of a second, meaning the image is also less grainy and less movement blur if there is any.

In the following image, you can see another shot of the same dog, taken during daylight hours in nature at f/1.8. The whole dog is in focus and that’s because the distance from the object was further, meaning more items look like they’re in focus. But the focal range is actually the same. Remember, the closer you physically are to a subject, the less in focus. The further you are, the more that’s in focus.

At the same time, when using lenses like the Canon 70-200mm f/2.8 USM IS L lens, if you are close to the subject, you will see this same effect, same as if you are further from a subject. A good thing about using a lens that allows more light in (lower f-stop), is also images that are near by will become blurred, distorted, and sometimes unseen. For example the image below was taken of an African Wild Dog, this image was taken through a metal fence in which you can see a slight distortion of when looking at the background, but doesn’t actually ruin the image and the African Wild Dog is in full focus.

The African Wild Dog was actually cropped down so it looks closer than it actually is. But the original image was taken at 168mm, ISO 2000, at f/2.8. Giving the image a lovely depth of field.

Now don’t be confused and think you can’t get a sharp, crisp image if you shoot landscape at a low f stop. In many cases, the zoom you have on the lens will help you see the results or not. For example the image below was taken at f/4.5 at 37mm. Focal length to subject distance also plays a large part and because the focal length was 37mm (x1.6 at cropped lens) there isn’t really anything out of focus in the image because there was nothing close to see this, to make it visible. The main focal area in this image was the boat.

Large aperture = Small f-number = Shallow (small) depth of field
Small aperture = Larger f-number = Deeper (larger) depth of field

To be proper for landscape photography, moreso when shooting things like mountains or forests, you will want to use an aperture of f/18-f/22. But if there is no subject that is actually ‘close’ you can get away with a lower aperture. But be mindful that at an higher aperture you will also get longer exposure times depending on the subject lighting. Shooting in dark or dense areas you may benefit using a tripod. Shooting in more open and bright areas you may be able to get away without one.

The best way to teach yourself though, is to go out with a camera, and practice different focal lengths, and that is when you will see the difference for yourself. It’s the best way to learn about depth of field. When shooting subjects in water, I try to get as close to the water as I can, as you can see below. This gives a nice effect and makes the subject a more interesting focus. Being an eye-level height with huma and animals can be a fantastic way of getting a more exciting image that does stand out than what it would be to be taking an image looking down on the subject or up on a subject – depending on what it is you’re aiming to photograph.

Depth of field is a large subject area, and the best way to learn it is going out with the camera and finding those shots… that just work! Don’t be afraid to get close to your subject. Don’t be afraid of getting to their level. Don’t be afraid to study them. These will help you understand how to capture those shots that just make you go ‘wow’, or for me ‘yay’!