What would be of our photographs without a correct approach? There is nothing worse than a malenfocada photo. We can work it well, we can frame it well, take care of the composition, the exposure, the white balance, stabilize the camera with a good tripod, and everything that comes to mind, but if the photo is poorly focused it will inevitably go to waste. So sad! Today I will explain everything you need to know about the focus on photography. I will explain in a first part how the approach works and we will see it with a practical example of real life. I will explain the elements that influence the approach so that it is done correctly , and then we will see when it is convenient to use the manual approach and when to choose the automatic one . Finally I will explain some things you should know about the autofocus .
HOW DOES THE APPROACH WORK?
Practical exercise: 1) Choose one eye that you will keep open and close the other, close it well, and close it throughout the exercise, make sure you have it tightly closed, you can use your hand to cover it. Make sure you have only one eye open. 2) Now put a pen or pencil upright between you and the computer screen. 3) Try to continue reading this while you have the pen between you and the computer, as you read this you will see the pen or blurry pencil. 4) Now try to focus on that pen or pencil, look at it, look at it for a few seconds, you will realize that this text has become blurred. !! Congratulations!! You just did a focus and blur exercise . The same happens in SLR photography. The image is composed on the lens or lens and then reaches the inside of the camera (to the sensor) already composed. The only thing it does is to record it as defined by the lens of the lens. It is very similar to what happens with the human being, when we look at something the image is defined in the eye, the eye is the one that focuses what we are seeing, and once focused it is transmitted to our brain that translates what we see, the brain would be the equivalent of the camera sensor, everything is recorded there. In a SLR camera, when we are in manual focus mode we turn the focus wheel on the lens and while we do it there are a series of crystals inside the lens that begin to move back and forth, thus achieving the focus we are looking for .WHAT ELEMENTS INFLUENCE THE APPROACH?
In approach it is a very sensitive thing. There are a number of elements that influence the approach and that, at the slightest alteration, spoil it completely. Let's see them:- Focal length: Take a lens of 18-105mm and put it in 50mm for example. Now let's focus manually. Once we have the focus already adjusted, any change in that focal length (more zoom, for example 105mm, or less 18mm zoom) will cause us to lose the previously taken focus.
- The approach itself: It is obvious but any change in the focus wheel, when it is in manual mode, makes us lose our focus.
- The distance of the subject: If you focus on a person and then ask him to take 2 or 3 steps back you lose focus.
- The diaphragm: This influences what is called the Depth of Field . I do not want to make a mess on this occasion, so we will discuss this point later in a future article. For now, you should know that the opening of the diaphragm influences the focus. It does not spoil it, nor does it correct it, but it has another type of influence that we will see another day.
THE MANUAL APPROACH VS. AUTO FOCUS
While compact cameras take automatic control of absolutely everything, digital SLRs almost always give us the choice between doing it manually or letting the camera do it for us. For me, doing things manually is the fastest and most direct path to learning and mastering photography, so if you've always let the camera focus for you, it's time for you to take the reins of manual focus a bit , This way you will learn a lot and fast. In addition, there are situations in which it is best to focus manually.MANUAL FOCUS
I find it very appropriate and more effective in the following situations: Macro Photography: As it involves photographing very tiny details and with great precision, we cannot risk with an automatic focus. It is best to focus ourselves on the object we want to photograph with pinpoint accuracy. Lack or lack of light: Some SLR cameras go crazy trying to focus on the dark. If there is not enough light, auto focus becomes a waste of time. When you don't have much light, it is best to focus on yourself. Portraits: For a successful portrait photography it is recommended to always focus on the eyes of the model. This can only be achieved through a manual approach. Photo through a glass:When there is a glass in between, the lens of the camera can be confused and focus on the glass instead of the outside. This is more likely to happen if the glass has some kind of dirt, dust or drops on it. For such situations, manual focus always. Multiple subjects and a single protagonist: If you have tried to photograph a friend in a busy street you will have noticed that the autofocus does not know who has to focus (logical, since our camera does not know our friend :-P ). The same happens if we have several adjoining objects and we are only interested in focusing on one in particular. Manual focus please.AUTOFOCUS
Personally I use the autofocus whenever I find myself in any of these situations:- In a hurry: if I'm in a hurry and want to take the photo quickly I prefer autofocus.
- When I do not see what I photograph: For example a posture in which I have to hold the camera very high to the point that I cannot see the screen.
- Self-portraits: I don't see myself in my self-portraits and therefore I leave the task of automatically focusing on my beloved SLR.
- Scenes with movement: If there is a lot of movement in what I want to capture, I prefer to let the camera take care of focusing and refocusing, although this is not always the case, but most of the time. There are some exceptions.
ALL ABOUT AUTOFOCUS
In autofocus, the camera intervenes and it takes control of the objective lenses itself, moving them in such a way that the thing is well focused, or at least that is what the poor camera tries. But how does it do it? There are a number of methods, technologies, ways in which today's SLR cameras can try to guess where is what we want to photograph and therefore focus on it: one of the most expanded methods is that of contrast comparison, the camera focuses on the contrast of colors between the different objects. There are also other methods such as infrared, which simply consists of emitting an infrared light and studying the light reflected by the object in order to focus it. Ultrasound is another method that some cameras like Polaroid use and that allows focusing without the need to resort to the lens or lens. In your case, the safest thing is that your camera relies on the contrast of objects to focus.HOW TO SWITCH BETWEEN AUTOFOCUS AND MANUAL FOCUS?
