04. Camera focus

Understanding focus is key to getting a good photograph as it’s critical that you get a part of your image in focus. This may sound simple — the camera does it all for you, doesn’t it? That’s often the case with modern DSLR cameras (when using film cameras often the only option was to focus manually), but in order to get the best image it’s still important to understand how focus works.

When taking a photo, light is directed through the lens before reaching the recording medium. The lens, regardless of whether it’s built into your camera or interchangeable, is made up of elements and these elements together are what focus the light. This can be done automatically, or you can focus the lens manually.

camera focus
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Manual focus vs autofocus

Whether you’re just starting out or already have some level of experience, chances are the terms manual focus and autofocus will be familiar. Lenses nowadays often feature both (when photography was still relatively new, this wasn’t the case) and you can set this on your lens (MF or AF).

Camera focus
© Karl Taylor Education

Manual focus is when the photographer manually sets the focus by adjusting the focus ring of the camera. Less commonly used than autofocus, manual focus is still particularly useful when the camera has difficulty focusing or when taking a series of images where you don’t want the focus to change.

Autofocus refers to the mechanism that automatically moves the elements within the lens in order to achieve the best focus. This is done through a series of autofocus points that are visible through the viewfinder — the camera (or photographer) selects a particular focus point and this is used to achieve focus.

camera viewfinder
camera viewfinder
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Above are two examples of what you can expect to see through your viewfinder. This not only shows how different cameras have different focus layouts, but how they also have a different amount of focus points, which you can use to select your exact focus position (it doesn't always have to be in the centre).

When it comes to your camera automatically selecting a focus point, this is done one of two ways: Phase detection or contrast detection.

Phase detection: This is the system most commonly found in DSLR cameras. The advantages of this system is that it is very fast and therefore great for tracking moving objects. Although the system doesn’t always get it right, this technology continues to improve.

Contrast detection: This system is commonly used in mirrorless cameras, point-and-shoot cameras, DSLRs in live view mode and smartphone cameras and is much simpler than phase detection. Although it is slower, it is much more accurate, which makes it far better suited to genres like product or landscape photography.

Depending on the model and make of the camera, different cameras have different focus systems, and different focus points. Depending on the focus mode you choose, you or the camera can choose the best point of focus. Some modern day cameras also feature eye detection, which can be very useful as this is often the best place to focus.

Focus modes

When using autofocus, there are a number of different modes to choose from, each of which are better suited to particular scenarios.

Single shot/Single-servo focus mode: Only one focus point is used to determine focus and this does not change until you re-focus. This is shown as ‘One-Shot’ on Canon / ‘AF-S’ on Nikon.

Single point focus example

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Continuous focusing/Continuous-servo: Once a focus point is set, the camera continuously tries to monitor the distance of the subject from the camera and readjust as necessary for as long as the focus button is held down. This is shown as ‘Al servo’ on Canon / ‘AF-C’ on Nikon.

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© Karl Taylor

Automatic autofocus mode: This is a cross between single shot and continuous focusing. The camera focuses on a single subject and only refocuses when the subject moves. Until that point, the mode behaves more like single shot than continuous focus.

Camera Sensors / Medium

Where to focus when taking a photo

Now that you understand how focus works and the different focus modes, the next thing you’re probably asking is “Where should I focus in an image?”.

This is a common question, especially for new photographers. Where you focus in an image depends on a few things: what you’re photographing and what result you want to achieve. From the example shown in the video, you’ll have seen how different focus points can have a big impact on an image.

Indoor natural light portrait photography example

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When selecting your focus, it’s important to think about two specific things: your subject and depth of field. What do you want to be in focus, and how much of the subject do you want to be sharp?

Depth of field (which is controlled by adjusting the aperture) will increase or decrease the sharpness either side of your focus point. We’ll look at this in more detail in the next chapter.

All content © Copyright Karl Taylor Education.

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Comments

  1. Question about focusing: I have shot dozens of basketball games for the Dutch national basketball association. This yielded around 30,000 shots over a few years, of which maybe 30% are in focus. After I stopped shooting games at the end of the 2018 season, I have switched to portrait subjects where I can direct the model. In the 15,000 or so images or so I’ve taken in that context, 30% in focus might be about what I’m getting.

    When shooting basketball, I started with a DSLR (Nikon D800), then switched to a mirrorless (Sony A7R), then to a medium format (Phase One DF+ with IQ250 back, later upgraded to an XF with an IQ3-100 back). With all of these cameras, focus has been an issue, though less with the Nikon than the Sony, and less with the Sony than the Phase Ones. The reason I switched cameras is that although focus became more and more difficult, image quality went up. Since I was able to capture so many images, I felt that I could afford to lose a few if the end result was a few excellent, as opposed to good, shots.

    The issues:

    DSLR: Continuous Focus (CF) mode was never fast enough to track the motion of a player moving directly toward the camera. For that reason, I usually shot manually. I’d pick a spot on the ground, focus on it, and then shot when players were about to pass through the plane of focus. If the players were at the far end of the court and I had a longer lens, I used CF mode, but it often tracked the wrong player or object, thus making it a bad solution. Ultimately, MF was usually best.

    MF: The Phase One camera autofocus is unreliable in low light, even with a modeling light shining on the subject (depending on ambient light). For that reason, I usually use AF to get close to the right focus setting, then adjust manually while looking at the live view on an iPad or laptop. The problem is that the focus is only good for that moment. As soon as the model slightly moves, the eyes go out of focus, or even a larger part of her body. In low light situations, this is hard to see and it is a pain in the neck to continually refocus in live view, a practice that is likely tiresome to the model. Lately, I’ve been shooting in total blackness, with colored continuous lighting to light a backdrop behind the model. The continuous light is shielded so it doesn’t hit the model, and the model is lit by a flash in front of her. I like the effect I get with this, but focus is a nightmare because as soon as shooting begins, the model is moving in and out of focus and I can’t see it happen with the low ambient light in the background. This forces me to frequently refocus.

    In the end, I get what I want but it is very time consuming. After looking at one of your videos, I got the idea that part of the problem is that I have been shooting at f/11 rather than f/16 or higher, yet it seems to me that f/11 should be good enough for a shooting distance of three to nine feet.

    What am I missing here?

    1. Hi, obviously f16 or even f22 will help but at the expense of a loss of light which can be compensated for with hight ISO or slower shutter speed. However f11 should be adequate only depending on the lens used, remember that depth of field is always linked to magnification. So therefore if you are using a more powerful telephoto lens or shooting macro or shooting something very close, then those are all instances of increased magnification and will result in less DOF, which is why when we decrease magnification as we do with wide angle lenses then the DOF always looks greater.

  2. Hi Karl,
    Despite using an aperture of between 4 & 5 on my canon mark 4, i cant seem to get sharp focus on the eyes and faces of the people. I want maximum bokeh as well, as its a family shoot.

    1. Hi Jaisal, what lens are you using? For example with an 85mm lens I can get the eyes sharp on a single subject at f1.8 and easily at f4. I’d run a check on your lens with your camera on a tripod and your subect fixed, like a pencil or something thin, to check the lens focusing. Do this in AF and MF.

  3. Hi Karl,

    How do you manage to focus someone by using an analog camera knowing that the focus is always at the center of the viewer?

    1. It was never easy but generally you’d point the camera at them and focus and then recompose and then hope that depth of field covered it. Alternatively if you’ve got good eyesight you just view the image to the left or right and make your best guess.

      1. Thank you s much for the answer, I like very much the way you explain technical issues. It is really interesting.

  4. Hi Karl,

    This is an excellent video!

    I wanted to ask, I have great difficulties photographing clear transparent quartz crystal clusters. The issue I have is that the quartz crystal has many clear long crystals branching out at different overlapping angles, and it’s difficult to capture the definition of the clear crystals the overlap each other in the main body of the crystal. Any suggestions would be greatest appreciated.

    Many thanks and best wishes
    George

  5. Hi Karl,

    Which is the best method to get the auto focus micro adjustment? I listen talk about the software that calibrate automatically, is this software a good option?

    Thank you very much

    1. Hi Justiniano, I know you can custom calibrate your autofocus/lenses on some of the Canons and maybe other 35mm cameras but I believe this is done manually in the camera menu, i’m not familiar with any other software for this purpose?

  6. Hi. Question. I use Sony A290, A390 & an A58 and on focusing on AF area I have 3 choices, Wide, Spot and Local. Which is best for what subject and metering modes, I get stuck on what I need to set it at too…can you help me get better understanding of this?

    1. Hi Steve, don’t get hung up on the focus mode or the metering mode. As you progress through this course you will come to learn why. Most of the time I focus manually anyway but if in autofocus usually the wide or multiple focus points works well. Forget about the metering mode as it’s not important as you are going to learn to use just as a guide while you make the decisions manually, leave metering on wide/matrix or centre weighted for the time being.

  7. Hi..
    what the no. That sometimes arise beside the green dot .?!
    And I’m really enjoying this course ..
    big thxxx..

    1. Hi Duaa, the numbers on the left of the green focus confirmation dot are the aperture setting and the shutter speed. These items are covered in the previous chapter and later chapters of this course. Cheers Karl.

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