Digital cameras all have a common option, the focus mode, if you are used to just take pictures without any manual intervention, than you might be interested in reading more about it. I want to talk about focus and why is important to know how your camera do it, and what are the options you can choose to make your photo style a little more unique and diversified.
I am not going deep explaining what focus mean, but just to make it clear and simple, the focus make the subject looks sharp, when you see a blurred subject it means the camera didn’t find the point of focus where the light passing through the lens didn’t touch the sensor at the same point but instead it spread on several parts of it. I found a good article talking about focus if you are interested to know more about it.
Before talking about focus modes, there is another important option you should know about that is focus points or focus area. A camera has fixed points or areas where it will try to focus on. On default settings the camera always try to focus on a wide area of the frame, the nearest subject get the focus. You can also change the area size or move it around the frame. On some cameras you can choose points of focus, disable them, and just leave the point where you have your main subject, that you want to focus on. This is helpful when you want to decide what to focus and not leave the decision to your camera, but not every camera has a fast access button that you can use to change this option.
A camera nowadays has three focus mode, Automatic AF, One Shot AF and Continuous AF, where AF stand for Automatic Focus.
The default option, in most cameras, is Automatic AF, or also called AI SERVO, when you half press the shot button, you will see the camera trying to focus on the near subject and if you move or the subject move, the camera will keep changing the focus point to always keep the nearest subject on focus. Now this mode is really good for subject that keep moving, but really how many times I need to shot moving subject? Not many at least for me. The problem with this mode is that you can’t compose your shot, if I want to focus my subject that is behind some other objects, I can’t use this mode, the camera will try to focus on the foreground object instead of focusing on my subject behind it. Another composition that might not work is when you want your subject on one side of the frame, in order to achieve this composition, you need to change the point of focus, but this slow down the process a little bit and depending on the camera it might not be that easy to change, you can also achieve this composition using the tracking mode but I will not talk about it since for me is just too cumbersome.
Composition, this is when you want to use the One-Shot mode or Single-Shot depending on the camera. When you half press the shot button the camera will try to focus on the nearest subject inside the focus area or under focus points and after achieved it will stop trying. Now with the shot button still half pressed you can recompose the shot, you can move the subject wherever you want and the focus point will remain on your subject, you can move your subject behind some object to make your composition more interesting and you will have a beautiful blurred foreground with your subject perfectly on focus, how cool is that?
This is one of those characteristics you can not find on a phone (I think) and give you so much options that even just this functionality alone make buying a camera worth the price.
Also called just AI FOCUS, this is the same mode as Automatic AF, the difference is that Automatic AF will start as One-Shot mode but as the subject move it will switch to Continuous AF. If you choose Continuous AF, the camera keep focusing on the nearest subject moving or not. Another major disadvantage of using this mode is the energy consumption, keep focusing has a big impact on the battery life.
So what I use?
I use One-Shot mode most of the time with one point of focus and if there is no point selector I choose the center area as small as possible. Like this I put the subject at the center, I do the focus, and I recompose the frame as I like. I recommend to use continuous AF if you want to take photos of your kids playing or other subjects moving.