What would become of our photographs without a correct approach? There is nothing worse than a blurry photo. We can work well, we can frame 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 irremediably go to waste.
How sad!
Today I am going to explain to you in a first part how the approach works and we are going to see it with a practical example of real life. I will explain you the elements that influence the approach so that it is done correctlyand then we will see when to use manual focus and when to opt for automatic. Finally I will explain some little thing that you should know about auto focus.
And if you want to go deeper into focus, don’t miss this mega guide that I have prepared for you with everything you need to know for a good focus in different situations, as well as a good dose of tips to focus well.
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 it is well closed, you can use your hand to cover it. Make sure you only have one eye open. 2) Now put a pen or pencil vertically 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 pencil blur. 4) Now try to focus on that pen or pencil, look at it, look at it for a few seconds, you will notice that this text has become blurry.
!! Congratulations!! you just made a focus and blur exercise. The same thing happens in SLR photography.
The image is composed in the objective or lens and then reaches the interior of the camera (to the sensor) already composed. The only thing the sensor does is record it as defined by the objective lenses. 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 an SLR camera, when we are in manual focus mode we turn the focus wheel on the lens and as we do so there are a series of crystals inside the lens that begin to move back and forth, thus achieving the focus we are looking for. .
It’s outrageous, but the human eye operates with the same complexity as an SLR camera lens or more, and yet we don’t need an instruction manual to focus properly. A baby can focus in a short time of life. It’s beastly.
What elements influence the approach?
Focusing is a very sensitive thing. There are a series of elements that influence the approach and that, at the slightest alteration, completely spoil it for us. Let’s see them:
- Focal length: Let’s take an 18-105mm lens and set it to 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 zoom type 18mm) 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.
- Subject distance: If you focus on a person and then ask them to take 2 or 3 steps back, you lose focus.
- The diaphragm: This influences what is called the depth of field. I don’t want to confuse you this time so we will deal with this point later in a future article, for now you should know that the aperture 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.
manual focus vs. auto focus
While compact cameras take automatic control of absolutely everything, DSLRs 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 have always let the camera focus for you it’s about time you took the manual focus reins a bit, so you will learn a lot and quickly. Also, there are situations where it is best to focus manually.
manual focus
I find it very appropriate and most effective in the following situations:
Macro Photography: As it is about photographing very small details and with great precision, we cannot risk with an automatic focus. The best thing is to focus ourselves on the object we want to photograph with pinpoint precision.
Lack or shortage of light: Some SLR cameras go crazy trying to focus in the dark. If there is not enough light, autofocus becomes a waste of time. When you do not have much light it is best to focus yourself.
Pictures: For successful portrait photography it is recommended to always focus on the model’s eyes. This can only be achieved by manual focus.
Photo through glass: When there is a glass in between, the camera lens can be confused and focus on the glass instead of the outside. This is more likely to happen if the glass has any type of dirt, dust, or droplets on it. For these types of situations, always focus manually.
Multiple subjects and a single protagonist: If you have tried to photograph a friend on a busy street, you may have noticed that the autofocus does not know who to focus on (logically, since our camera does not know our friend :-P). The same happens if we have several neighboring objects and we are only interested in focusing on one in particular. Manual focus please.
auto focus
I personally use autofocus whenever I find myself in any of these situations:
- Great hurry: If I’m in a hurry and want to take the picture quickly, I prefer autofocus.
- When I don’t see what I photograph: For example a posture where I have to hold the camera very high to the point where I can’t see the screen.
- Self-portraits: In my self-portraits I don’t see myself and therefore I leave the task of autofocusing to my beloved SLR.
- Moving scenes: 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 is some exception.
All about autofocus
In the automatic focus, the camera intervenes and takes control of the objective lenses, moving them in such a way that the thing is well focused, or at least that is what the poor camera tries to do. But how does she do it?
There are a series of methods, technologies, ways with which today’s reflex cameras can try to guess where what we want to photograph is and therefore focus on it: one of the most widespread methods is that of contrast comparison, the camera focuses based on the color contrast between different objects.
There are also other methods such as infrared, which simply consists of emitting infrared light and studying the light reflected by the object in order to focus it.
Ultrasound is another method that some cameras such as Polaroids use and that allows you to focus without resorting to the objective or lens.
In your case, the safest thing is that your camera relies on the contrast of the objects to focus.
How to switch between autofocus and manual focus?
Obvious question but among my readers there are always some stragglers 😉 You can switch between autofocus mode and manual focus mode usually on the side of the lens, there is usually a button that indicates (A/M) or AF and MF. Moving it towards M (or MF) we will be in manual mode and we can start moving the focus wheel and thus focus to our liking. What are we tired of? We put it back in the A (or AF) and that’s it.
Note: Some lenses use M for manual mode and A/M for a hybrid mode that allows auto as well as manual.
Is all for today. With this you should already have a complete vision on the subject of focus in SLR cameras. I have tried to make the article as easy and instructive as possible, avoiding as much as possible all those technicalities and jargon that are usually scary. I would have liked to go into more technical details but I’ll reserve that for another time. By now you should know how to take good approaches.
Can I ask you a favor? Only if you liked today’s article or found it interesting, please help me spread it, recommend it. That is all.
That said, practice.