Question? Focus Modes/ Focus Points

I recently received an email asking me which focus modes and focus points I use. I started to answer the email and decided I would share it on my blog instead. It is important to remember that I shoot primarily with Canon gear and I use the shutter button to focus. This information may be pretty basic for some of you but remember we all have to start somewhere and since I teach a lot of folks that are just moving into bird photography, all of this may be helpful to them.

Focus points:

Autofocus points aka AF points are what the camera uses to focus on a subject. When you are set on automatic AF selection, you’ll know where the camera is focusing by which AF points light up when your shutter button is pressed halfway down. When you select all of your focus points you are asking the camera to decide where to focus. I prefer to use Single-point AF as this is where you work with only one AF point, and that point can be moved manually anywhere within the AF array of available focus points. This gives the photographer complete control over what the focus point area should be.

So why not decide for yourself all the time?

Well, there are times when the camera can do a great job in making a focusing decision for you. If you have a solid colored background like a clear blue sky and you have a bird fly into that background; the job of the camera is easy and you will most likely get your shot. However, if the background is busy or there is low contrast than it has been my experience that the camera cannot pick up the subject from the background as easily and that is where single point focus comes in handy as you are able to decide quickly and force the camera to focus where you want it. Recently, I have been experimenting with Expand AF and Surround AF but I never use Zone AF or Auto Selection AF.

Below is a video tutorial by Rudy Winston from Canon that goes over each of the AF Area Options for those of you that may want to go through them all:

Ok, now onto Focus Modes…

Auto focus works in one of two ways with Canon, either in “One-Shot” mode or “AI Servo” (AI stands for Artificial Intelligence). There is a third focus mode called “AI Focus” which is basically where you let the camera decide which of these two it should use. For example if you are shooting a still subject and it starts to move the camera should switch automatically to “AI Servo”. However, I have been told by some experts that “AI Focus” is not reliable and was initially designed for beginners. I have also heard some pros refer to it as the focus mode that you use when you don’t care if you acquire focus–LOL. I never use it.

The difference between these two modes is this:

“One Shot” is best suited for still subjects because once you have acquired focus on a subject, provided you keep your shutter button pressed half way down, the focus won’t shift. This allows you to re-frame your subject. However if your subject is walking towards (when the focusing distance changes) you will have trouble keeping focus on your subject.

“AI Servo” is better suited for moving subjects when the focusing distance keeps changing, like birds in flight. So while you hold down the shutter button halfway (*if you are not using Rear Focus), the subject will be focused continuously—that is, until you move the focus point off the subject, then the focus will try to adjust.

* I don’t like using Rear Focus, especially for flight photography. In my opinion it makes you work twice as hard.

Photo of me, courtesy of Jim Fennessy.

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6 Responses

  1. Jim Fennessy says:

    Thanks for the photo credit. But I was trying to shoot the glacier and mountain behind you there in Alaska, and my camera accidentally focused on you only because my focus was set to automatic:) If my focus had been set to single point that glacier would be sharp:)

    Seriously, your flight photography in single point is amazingly good. You are way better than the camera could ever be at keeping that point on the bird’s head as it flies erratically through the air and through trees and contrasting backgrounds. I go back and forth between single point and group (the small diamond in Nikon) because even though my group autofocus sometimes locks on the bird’s tail (leaving my bird’s eye blurry), I still may lose less open sky flight shots then I would if my single point went off the bird entirely and focused out to infinity (which takes longer to recover from). As my flight tracking improves, I will do more and more single point shooting.

    Hi Jim, your photography has improved so much. It is due to your dedication and passion. No need to do what works for me, keep practicing what is working for you 🙂
    denise

  2. Very helpful pointers Denise. For “portrait” shots (i.e., non-flight) I will sometimes switch from AI Servo to single shot mode and select Canon’s “Spot AF” (single AF point that’s a square within a square) to achieve fine focusing depending on subject lighting/contrast (e.g., on the bird’s eye). I am curious to know whether you use Canon’s Case 5 or 6 (or perhaps a custom selection of values for AF tracking, AF point switching, etc) when shooting in AI Servo mode (I typically use Case 5). As I’m sure you know, Rudy has many excellent tutorials on a variety of topics that your Canon followers can search for at: http://learn.usa.canon.com/

    Hi Stephen, I find myself using Spot AF for flowers, especially when I want to focus on an edge. I don’t shoot portraits but if I did I would probably use it all the time!
    Since I shoot with single point focus most of the time and I am doing the tracking manually; I don’t use any of the case settings as I consider them to be more like presets. However, I have lately been using expand and surround a bit more so on “my menu” I put the tracking sensitivity, accel/decel and AF point switching so that I can change them easily for a given situation if I feel that I need to.
    denise

  3. Being a Nikon shooter, this helps somewhat. I like back button focus. However, I notice the AF diamonds switch from eye to shoulder or body or tail. I’m wondering if my cheek is moving the toogle buttons on the Nikon D5 and/or D810. Does canon have dynamic focus? With Nikon, you can choose between d51, d11 or d9 focus points.

    Hi Kandace, Depending on how you have set up your autofocus and if you have selected all of your points or even a few of them, your camera is moving them as it decides where to focus. Try setting your AF point to one and moving it around manually, then put your cheek up to the camera–is it moving it? Probably not, I am sure that your focus points are moving on their own trying to acquire focus. The focus selection can be made by the photographer or left up to the camera.
    Yes, Canon users have several options to choose from just as Nikon does.
    denise

  4. Krishna Prasad says:

    Thanks for the great Information.

    I am always pleasantly surprised when you say that, you always use single point focus for photographing Birds , Birds in Flight.

    I never managed to do the same.

    Hi Krishna,
    I found that it took loads and loads of practice to be able to shoot with center point focus only but once I got the hang of it my flight photography improved. See you in Bosque!
    thanks, denise

  5. Tim Clifton says:

    Thank you for your comments on your focus point selection. It is very much appreciated.

    I have been practicing photographing ducks taking off from a pond. You can usually get a bit of warning by the bobbing head and then an explosion of motion, and fast acceleration out of the water.

    It is very difficult for me to keep the single point or expanded on their head or breast. If you are far enough in front of a duck and it takes off towards you, it is much easier. A close duck on its front quarter can be maddening to catch with single or expanded AF points.

    Any suggestions?

    Hi Tim, I can’t agree with you more! A bird at close range taking off towards you is one of the hardest shots to get. I use single point and pre-focus at the distance that the bird is, with rapid fire in AI Servo mode. I do not use Live View for action shots. If you are having any success with any of the focus point selections than stick to it and try to work on improving. I can’t give you too much more advise than to stick with it and know that everyone struggles with that shot 🙂
    denise

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