Landscape photography - depth of field
The depth of field is one of the most important elements in achieving a great landscape photograph. It is what determines what part of the image is sharp and what part isn't. The depth of field can be controlled by adjusting your aperture or focal length.
A wide open aperture will create a shallow depth of field, while a very narrow aperture will create more sharpness in front and behind the subject. A narrow depth of field creates more contrast between the areas which are in focus and those that are not, resulting in an image with deep detail which can make it easier to pick out specific features such as leaves on trees or flowers from afar, but at some cost to background detail.
It is important to be mindful of the depth of field in the image you are trying to capture. It may often be possible to increase your camera's depth of field by zooming in, or more specifically by changing the field of view. If combined with a wide aperture and a slow shutter speed, it is even possible that you can get everything in focus that is visible within your frame.
At the other extreme, narrowing down your aperture to increase the depth of field will at first seem counter-intuitive, and may even feel unnatural. For instance, if you are shooting indoors with a close up of a plant, a small aperture such as f/22 can create enough depth of field such that only the subject is in focus. This creates the possibility that everything else may become blurry or lost in shadows.
But by being mindful of where your subject is positioned within your image and by choosing an appropriate aperture, both foreground objects can be sharp and well-defined without risking blurriness behind them. In addition, this kind of depth of field can lead to an enclosed space through which we perceive everything within as being in focus.
Depth of field is a very powerful tool which, combined with some other landscape photography techniques, can make it easier for landscape photographers to create alluring images.
How does it work? Depth of field depends on two factors. The distance between the lens and your subject, and the size of your aperture. Large apertures will have a shallow depth of field, while small apertures will have a greater depth of field. This means that focus can be placed at different distances from your lens depending on how small the aperture is that you are using, and through what degree it is open (the smaller the f-number, the closer one has to place things to get them in focus).
The distance between the camera and your subject is important because it increases with distance. This can be both inconvenient, as it means that landscape photographers have to get closer and closer to a far away subject in order to get all of it in focus, but it is also useful because it means that you can work with a very wide aperture while still having enough depth of field to make your foreground look sharp.
When working with smaller apertures (larger f-numbers), your depth of field increases. Let us say that you have a 35mm lens, and you are taking photos at f/16. In this case, things which are as close as 0.50 feet from your lens will be in focus. At f/22, things which are 6.00 feet from your lens will be in focus. This means that you can take photos of a landscape which is very far away – one which you could only see if you stood on a hilltop with the right kind of viewfinder to see it, or were able to build a so-called telephoto lens with such a large aperture for your camera.
With these considerations in mind, improving depth of field by using a wider aperture can lead to more practical work for landscape photographers who often have their subjects millions of miles away in foreign countries (mountains and other such geographical features are often very far away!).
In terms of size, bigger apertures will generally have a greater depth of field. This means that the f-number can be even smaller, thereby increasing the aperture size and allowing you to have a wider aperture for your lens which will still give you enough depth of field for your foreground. This is often desirable because it increases the possibility that you can focus on your subject easily without having to move too far away from it (something which is particularly important when shooting with telephoto lenses).
Depth of field in reality depends on many factors, but it is important to be mindful of how large the f-number you want to use is. To make things even more interesting, the effect of your lens' something that will be much clearer when you look out for them. This means that if you have a very small depth of field, it may look difficult to get your foreground sharp. At the other end of the spectrum, it can be very frustrating to open up a large aperture to get your foregrounds sharp and having them "all blurry out".
In general, this happens when you are using an extremely large aperture. A very wide aperture will at first seem unnatural with landscape photography because it often makes all objects appear flat and rather shallow – especially in real life. But this can be overcome.
In practice to improve depth of field, you should zoom in (if it is possible) and use a wide aperture – giving your foreground a lot of sharpness.
You may experience problems with sharpness when your foreground has a large depth of field compared to the distant background. At times, you will find yourself struggling with this problem so much that the only way to fix it is by moving closer to the foreground elements that are in focus while making sure that your lens is pointed at an angle which makes sure that more elements are visible on a single plane.
When you are working with a large depth of field, there is one more helpful trick which can help to make your foreground stand out from the background. This is known as "chromatic aberration" (also known as "color fringing"). In short, it refers to images in which some edges around objects are not sharp. This might happen because the light sensor used in your camera has slight defects in it (these defects are known as "lenses"), or because you have used a lens that has defects such as chromatic aberration.
Conclusion
Depth of field is a very useful tool in the hands of landscape photographers.
Firstly, it makes it easier to create a sense of enclosure (through which we can perceive everything within as being in focus). Secondly, it can lead to sharpness without blurriness occurring behind your subjects. Thirdly, this can be accomplished with faraway subjects which are difficult to achieve with other techniques that landscape photographers often use such as telephoto lenses or alternatives such as wide angle lenses.
This kind of depth of field is particularly useful for landscape photography because it maximises the possibility that we can take photos of all three elements (foreground, background and middle ground) at the same time.