Focus Modes on Your DSLR
Focussing is critical, learn which focus mode to use
Focus Modes - Do you generally shoot in One Shot or Servo Mode? Are you one of the few that uses, or even knows the benefits of AI Focus (the other mode that no one uses)? Many digital cameras, particularly DSLR's, give you the choice of either AI Servo or One Shot focussing.
Again, what you choose normally depends on your own style and what you are photographing at the time. I personally switch between the two but on most occasions use one shot focussing.
One Shot
This is exactly what it says, focussing. The camera will focus correctly for one shot and then you would need to release the shutter button. Then press again for a new focus point on your subject. This is a great way to lock in focus for your subject. Bear in mind that should the subject move, you will lose focus and need to release and press again to obtain focus.
This is particularly important to remember if you are using wide apertures and shallow depth of field. It is very easy to lose focus even if the subject only moves a couple of inches.
I use one shot focussing as my main focus mode. Coupling this with just using the central point in the viewfinder and the audio (beep) switched on for extra confirmation that focus is locked. I find this gives me complete control over focussing at all times.
AI Servo
This is a bit more interesting and great technology for sports or wildlife photography as the camera and lens will constantly work together and focus on and adjust for any moving subject within the frame.
E.g. Let's say you are on safari and a leopard is running towards you at great speed. If you are silly enough to stay and photograph this monumental (or just mental) occasion, then beware. If you have your focus mode set to One Shot, you wouldn't be able to make good use of your continuous mode. Whether it is 5, 8 or 10 frames per second, you would need to be repeatedly pressing and releasing the shutter button to refocus each shot.
If you didn't, the big cat would become more and more out of focus as it approached with the original point of focus nicely sharp all the way!
If you had the camera set to AI Servo on the other hand, you could just keep your finger pressed firmly on the shutter. You could do this knowing that the AI Servo tracking focus is taking care of everything. Right up to the point of your untimely death!
Intelligent Sensors
Most modern DSLR's also have sensors amongst the focus points that determine which part of the image is moving. This means you can set the focus points to ALL and be quite certain that the camera will track your subject.
So for sports and wildlife photography, the best set up may well be to use all focus points with AI Servo focussing if your camera allows it. But again, it still takes a lot of practice to get it right so don't always rely on the camera to get it right. It still needs a lot of user input.
Manual
Of course, there are times when you will either want to, or need to come out of the auto focus modes and switch to manual focussing. One of these times is when shooting macro photography.
With macro, the room for error is so small due to limited depth of field so even the minutest of movements can cause a blurred image. If using autofocus with macro lenses, you are asking for trouble as the lens hunts for focus and doesn't know exactly what YOU want to be in focus.
Using manual focus and a tripod will not guarantee focus to be spot on but it will give you the best chance.
Again, practice is key with critical focussing. You may also want to use manual focus when the subject and your camera are static.
This will guarantee correct and consistently accurate focus for each shot, which is particularly useful for night landscape photography when it is difficult for autofocus to lock in place.
A tripod will help
Using manual focus and a tripod will not guarantee focus to be spot on but it will give you the best chance. Again, practice is key with critical focussing.
The following video was made in June 2021 with the Panasonic S1H and ageing Sigma 105mm f2.8 lens. Camera was on a tripod with manual focus and a slightly windy piece of wheat.
Click to play
You may also want to use manual focus when the subject and your camera are static. This will guarantee correct and consistently accurate focus for each shot, which is particularly useful for night landscape photography when it is difficult for autofocus to lock in place.
We cover all this in greater detail over at ATP Members. We have videos to illustrate this in more detail with many sample images and techniques.