– Article by Deon
Technique: Back Button focusing: Nikon D7000 and Canon 7D
Basic focusing methods:
Most camera focusing systems depends on two basic issues. First, we have to determine how the focus system will react in relation to the shutter release button. Secondly, we have to determine where in the frame the camera will focus. For the sake of this article, we will mostly concentrate on the first issue. Although different camera models might call these different names, we get three basic ideas on how the focus system will react with the shutter release button.
The first idea is Single or One Shot focusing…
What this means is that when you press the shutter release button halfway, you get one focus for one shutter release. This also automatically activates focus lock. In other words, when you get focus, it will be locked, while you hold your shutter release halfway down. This gives you the opportunity to recompose and shoot. This is probably the most popular way of focusing and very effective when you shoot portraits, landscapes or anything that does not move fast.
The second idea is Continuous or AI Servo focusing…
In this mode, the camera will keep on focusing while the shutter release is pressed halfway. There is no focus lock involved and the camera will keep on focusing. The camera will also activate intelligent systems to track focusing of moving subjects. The focus system will not wait for the shutter to be released and the shutter release and focusing system works totally independent from each other.
The third idea is the Auto Servo or AI focus…
This one is easy. It is an auto selection of the first two ideas. In practical terms, it works like this. When your subject is standing still your camera will automatically choose single or one-shot focusing. As soon as your subject starts to move, your camera will detect this movement and will automatically switch over to continuous or AI servo focusing. This is usually also the default setting of your focus system on your camera. This is a system that I do not use a lot because it is my experience that you do not always know what system the camera has chosen and it becomes difficult to know instinctively what your reactions should be.
Is there an easier way?
I recently saw an interview with a National Geographic photographer who claimed that the only way to focus effectively, without switching between settings and programs is through “back-focusing”. He further claimed that this method is intuitive and once you get the hang of it, it is easy to use.
Whether you have moving or still standing subjects this is the way to go, without always having to make focus system decisions. This opens up the mind to concentrate on other equally important things like exposure and composition. I decided to investigate this and I am sold completely.
Use the Back Focusing Button!
There is another way of handling your focusing system. This method is called back focusing, and it is getting more and more popular with professionals, as they switch over to this practical way of working. It is intuitive and it combines the two main focusing systems into one action. It will take a while to get used to this, there is a learning curve, but as soon as you are used to it, you will never turn back to your old ways. The idea is remarkably simple and easy to use.
This is how it works:
You set your camera up in such a way, that your AE/AF lock button (Nikon), at the back of your camera and in the case of Canon, your AF-on button at the back of your camera, becomes your focus button.
Advantages of using the Back Focusing Buttons
- The focus will then be totally separated from your shutter release button.
- The shutter release button will now only be used as a shutter release. No focusing will be activated by this button anymore.
- You have to set your focus system up in the continuous servo or the AI servo mode.
- This will activate continuous focusing.
- Your AE/AF lock button (Nikon) or your AF-on button (Canon), will now act as a two-way focus button. If you press this button, your focusing system is activated and it will also activate your focus tracking systems to track moving subjects. You then shoot your moving subjects in the normal way. When you get focus and your subject is suddenly in a stationary position, you simply release this button and focus lock will be activated and you have the opportunity to recompose your shot and shoot, as with one shot focusing.
- You can also combine this workflow with multiple point selection (Canon) or 3D focusing(Nikon). This is fantastic!
- You use your relevant multi-controller to select a focusing point. This could be the middle point or any other. You place this point on the subject that you want to track, let’s say it’s a bird in flight. As soon as you press your focus button and hold it, your focusing system will kick in, using your selected point as a starting point. The system will now use all the other focus points to track the movement.
- If the bird ends up on a branch and is stationary, you simply let go of the focus button and focus lock will be activated and recomposing your shot will be easy. When the bird takes off again, all you do is to place the selected focus point on it and press the focus button and the relevant intelligent systems will activate in order to track the movement.
- When shooting portraits, you choose the focus point closest to the eye and place it on the eye. Press the focus button once to focus and then let go of the button and focus will lock in order to recompose.
- This one focus button now changes into a double duty function.
- Press in to activate focusing and all the relevant tracking systems on your camera.
- When your subject is stationary, you simply let go of the button and you have focus lock in order to recompose.
- When shooting portraits, you choose the focus point closest to the eye and press the focus button to focus and then let go of the button and focus will lock in order to recompose.
Setting up your Nikon D7000
- In the main menu go to function controls. This section is indicated with the pencil icon.
- Go to “Assign AE/AF-L button” and press OK.
- You then select “AF-ON” and press OK.
- The camera must also be set up so it will take a picture, even when focus has not been achieved. This is preferable in most situations because you may have focused and recomposed the shot. Go to your Custom Setting Menu and choose Autofocus. Select “AF-C priority selection” and set it to “release.” Then set AF-S priority selection to “release” as well.
- On the left-hand bottom side of your camera, next to the lens on the camera body, you have the auto focus selection switch. On top of this switch, there is a little button. You press and hold this down while you change your back selector dial at your thumb until you have activated the Continuous-servo mode.
- You then do the same and change the front selector dial at index finger until you have activated your 3D area mode.
- On the back of your camera, just under the multi selector, you change the little switch to L for lock. This will enable you to choose any one of your 39 focus points, as the starting point of your focus tracking.
- In the main menu go to function controls. This section is indicated with the pencil icon.
- Go to “Focus tracking with lock-on” and press OK.
- Here you can choose between short and long intervals before refocusing while tracking. Short intervals will give you a much more sensitive tracking but this will also be more susceptible to re-focusing, should anything else enter into the frame. If you choose a longer tracking interval, your tracking will be less sensitive but this will mean that it is also less sensitive to re-focusing, should anything else enter into the frame.
- You use short intervals when you track something all on its own. You use long intervals when you track something that is within a crowd.
Setting up your Canon 7D
- In the main menu go custom functions.
- Go to custom function 4:1.
- Select the shutter release button and select “Metering start”.
- Also, select the “AF-on button and select “Metering and Af start”.
- In the appropriate spot, either on the top panel or in the Q-menu, select “AI-Servo” mode.
- Press the focusing button at the back right-hand top of the camera and also press the M-Fn button next to the shutter release. If you keep on pressing these two buttons the camera will change the focus point selection modes. Choose Auto select. You can also use the Q-function for this.
- You can now use your multi-selector to choose a focus point. This will enable you to choose any one of your 19 focus points, as the starting point of your focus tracking.
- Go to Custom function 3:1. Here you can choose between short and long intervals before refocusing while tracking. Short intervals will give you a much more sensitive tracking but this will also be more susceptible to re-focusing, should anything else enter into the frame. If you choose a longer tracking interval, your tracking will be less sensitive but this will mean that it is also less sensitive to re-focusing, should anything else enter into the frame.