There are three photographic aspects that concern you and about which you demand more information, and it is not for less, since they are essential topics. And these are lighting, composition and focus on photography.
For the first two I have already prepared two mega guides (you can find them by clicking on the links) in which I compile all the information I have in my hand and I leave you all my tips and tricks.
Today it is the turn of focus. A topic with a lot of crumb that I hope, with today’s mega guide, clarify everything I can. At least what is within my reach. And as you know, in the simplest way possible, as I would have liked to be told, without weird words or complex explanations 😜
Get comfortable and, above all, save it in favorites or somewhere where you have it handy for when you need to refresh your memory.
INSIDE THIS ARTICLE… 📖
What is focus in photography?
Focusing in photography is a mechanism that occurs inside the lens and serves to locate the configuration with the highest degree of contrast and sharpness in the framed scene. There are two types of focus in photography: manual and automatic. The focused area of an image is that sharp and contrasted area, the one whose edges are perfectly delimited and clear, although the rest is blurred.
In the following example we have the focus on the F, that is, it has focused on the letter F.
According to the RAE (Royal Spanish Academy), focusing is:
“Cause the image of an object produced at the focus of a lens to be collected clearly on a given plane or object.”
Royal Spanish Academy ©
Look at the following image:
Am in focus when the image I project passes through the lens and precisely joins on the sensor plane; same as in the first image. On the contrary, we say that an image is out of focus, when the image is formed outside the sensor plane, either before or after, as you can see very clearly in the second image. And this is enough theoretical toston.
What you should know is that the focus direct our gaze, tells us what is important in the image, and even in what order and in what line we should look at it. It tells us if that image is transgressive, if it complies with the rules, or if it is simply worth nothing more than for the trash can because it is a blunder.
And, oddly enough, the failures related to the focus in photography are the most recurrent and insurmountable in terms of errors. Don’t worry, we’ll talk about them and how to avoid them right away.
What are the types of focus in photography?
Two exists types of approach, manual focus and auto focus. Each one with its peculiarities and its applications in specific situations. Originally there was only the manual focus, then the automatic mode emerged and currently they coexist in harmony because it is not that one is better than the other, but that each of them is appropriate for certain moments.
To switch from one to the other, you must do it through your lens, moving the button from M or MF (Manual) to A or AF (Auto) or vice versa. Although some lenses only allow manual focus.
Manual Focus (M/MF)
Manual focus is where you have to manually focus by turning the focus wheel of your target.
Autofocus (A/AF)
Autofocus is the one in which your camera focuses automatically, it is she who through the focus motor tour that wheel.
To dive deeper into auto and manual focus, click on the link.
focus systems
As I just mentioned to you regarding autofocus, there is a focus motor but also a focus detector. This analyzes a small area of the image (the one you decide you want in focus) and if its edges are defined and well contrasted, it allows the shot, however, if it evaluates that it is not, it sends the order to move the lens through the focus motor and so on until it feels it is in focus.
Not all focus systems work the same. There are different types and none is perfect, each one has its advantages. Talking about them can give for an entire article, but it is pure theory so I summarize here what is important in case you want to take it into account when buying a camera or knowing what the advantages or limitations of your camera are:
- Phase detection focus. It is the one used by SLR cameras except with video mode and Live View mode. It’s very fast and accurate, which makes it ideal for moving subjects, but a calibration failure can cause problems with back focus either front focus. In addition to being a complex and expensive system.
- Contrast detection focus. Used digital compact cameras and SLRs in Live View mode. It is a less complex system than the previous one but it has the advantage that it does not present problems of back focus either front focus; doesn’t need as much light or texture in the focus area; does not require specific focus points, can focus on any part of the image; and enables more complex algorithms that can perform face detection and tracking. On the contrary, in video it is slower and the change of focus from one subject to another of a different plane is not as smooth.
- Hybrid approach. It is the newest and the one we will see the most in the future (unless something new and better comes out). At the moment, due to its speed and precision, it is the system that mirrorless camera manufacturers are working on and that is also being introduced in the latest SLR or advanced compact models.
autofocus modes
Let’s now focus on the use of autofocus. The autofocus or automatic focus is divided into several types: AF-S, AF-C, AF-A for Nikon or One Shot, AI Servo, AI Focus for Canon.
The differences between them basically lie in the movement or not of the subject or of what we are going to portray:
- AF-S or One Shot: The simple approach It is the most precise but also the slowest, which is why it is indicated when photographing subjects or objects. static and in situations where you anticipate that what you are photographing is not going to move.
- AF-C or AI Servo: The continuous focus used to photograph moving subjects. With it you focus on the subject and it will track as long as you have the shutter button pressed halfway. Once you decide to take the picture, you just have to press the shutter all the way down.
- AF-A or AI Focus: In some cameras there is a third type that is indicated when it is anticipated that a static situation may become one in movement. This mode is capable of switching from a static system to following the moving subject automatically. For example, it is useful with animals, pets or children when they are supposedly still and you don’t know how long that calm will last 😉 .
Focus area in photography: What is it and how is it used?
When you focus in auto mode, you can choose whether to focus by selecting one point, multiple points, or letting the camera take complete control. In some models what you tell the camera is to focus on an eye, or a face.
That is, we use the area of focus, to tell the camera what the image area where we want to place the focus. This is called focus area or focus point selection, although its name or the different options depend on each brand of camera.
Furthermore, within each brand, two models from different ranges may offer different areas of focus. Higher-end cameras often offer more options.
That is why it is very important that you review the manual of your camera and discover what possibilities you have when selecting the focus points. These are some examples of cameras from different brands.
Pentax KP Active Area AF
Nikon Z50 AF Area Mode
AF area selection in Canon EOS 77D
Focus areas Sony A6000
Despite the differences, there are usually three general options regardless of make and model:
Single point selection
Single point selection (or spot focus) is the most precise option, since you tell the camera exactly where it should direct its focus, limiting the focus area to a minimum and, therefore, leaving no room for maneuver to the camera. This system is the most accurate, although it is not valid for all situations. It is recommended for static subjects.
Dynamic selection area
This type of focus allows you to select, as in the single point, a focus point. The difference is that, based on this, the camera selects an area around it that you can enlarge and reduce depending on the amount of area in which you foresee the action happening. This system is recommended for moving subjects or static scenes where you can anticipate movement.
Automatic selection area
In this case, it is the camera that decides what it should focus on based on certain pre-established parameters, such as the focus of what is closest to the objective (distance), what is larger, or what looks like a person by tone ( contrast). It’s not very precise and not always your parameters and its will match, so it has quite a bit of margin for error in situations where the center of interest is not clear or does not match the size, distance or contrast parameters. It usually works best when the main subjects are in the foreground.
Types of focus points in photography
Although when you look through the viewfinder or on the screen they all look the same, there are actually two types of focus points when it comes to a phase detection focusing system: linear and cross.
- linear. They only take into account the horizontal or vertical dimension to focus.
- crosswise They are more precise because they take into account both dimensions to focus. Use them when you want greater precision or when it is difficult for you to focus automatically (for example due to lack of contrast).
To find out how many cross points your camera has and/or what they are, you have no choice but to look at the instruction manual. I know, it costs, but each camera is a world and there is no other way to know it, so… go ahead! Open it that doesn’t bite 😜
Other concepts related to focus in photography
There are a lot of concepts related to the focus in photography beyond what I am mentioning and that you should know. From depth of field to dissociated focus, through hyperfocal, minimum focus distance, etc.
Surely you have ever come across any of these terms and you may have had some doubt or even scared yourself. To remedy this, we have an article on the blog that will answer all your questions about the approach. Do not miss it.
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