Understanding the Focus Points
Many people use all focus points on their DSLR, learn to break the mold!
Most modern SLR cameras have an array of focus points ranging anywhere from 5 to 75 and more. these are within the viewfinder. You can normally select either one specific point or all points at once for auto-focusing. Having 45 focussing points can be advantageous and impressive. However, it can also have its downsides. So how and when do you use how many points?
Everyone has their personal preferences when selecting focus points on a Digital SLR. I personally, normally only use the centre point for most of my photography.
It takes skill and practice to do this effectively especially when you take into account other factors such as composition.
Single, Centre Auto Focus Point
I generally use this single, central point for most of my photography work because I like to be in control. By using this effectively, most of my images are sharp at the point I want. Not the camera's choice!
If the subject that I am photographing, or the point I want in focus is off-center, I aim the focus point directly where I want to be sharp. I do this:
If the lighting situation means that by doing this I lock in the wrong exposure, I will first of all take a separate "exposure lock". Locking in using the * button (on most digital SLR's), and then do the above. That way I am more than confident that the image will be sharp and correctly exposed every time.
That is as long as I shoot before the timer on the exposure lock lapses. Of course, I take a few just to be sure!
Shallow Depth of Field
Let's say you want a dramatic, close up shot of a persons face and want to use very shallow depth of field for effect. You also want to keep just the closest eye tack sharp leaving the rest blurred. By using normal auto focus methods with all focus points, the camera would more than likely focus anywhere other than the closest eye. This would make the shot that more difficult to get.
Using my method above and locking the focus on the eye and re-composing, I can ensure the shot looks great with the exact point I want in focus.
This works well for most types of photography including:
...but doesn't work too well for sports and nature photography. For that you are better off using all focus points (below).
Specific, Single, Off-Center Auto Focus Point
If your camera has this function, then you are able to select just one of any of the focus points as reference. This only really works if you are taking many shots of the same subject in the same location within the frame and you don’t want to keep moving the camera as in the example above.
For example, you are doing a commercial or stock shoot of some bottles or glasses of wine all in a row. You want them fading into the distance using shallow depth of field. Getting just the first glass, on the left of the frame in focus whilst the remaining bottles fade and blur into the background is key.
You would put the camera on a tripod and compose the shot just how you want it. Then you would select the focus point that lands on the nearest glass. This is to make sure that every shot you take of this set up has the first glass on the left well in focus.
There are many other circumstances where this would come in handy, using any of the focus points, but hopefully this example has covered the basics.
All Focus Points
As we touched on briefly before, there are only a few situations where I personally would use all points. Being mainly sports or nature photography with subjects that move independently and erratically.
These would be particularly useful for fast moving objects where it is virtually impossible to keep them over any single point. By selecting all points, the smart chip in the camera decides which point the moving subject is closest to and switches back and forth instantly to keep the subject well in focus.
This works particularly well in unison with AI Servo mode which we shall cover in a bit. Panning (above) with and keeping the subject as still in the frame as possible also helps the camera keep track. If you were to use all points with, say, portrait photography as discussed above, the camera may well select the wrong point of focus entirely leaving the all important eyes blurred.
This is where many "newbies" go wrong with their new Digital SLR's. Through no fault of their own, they would be right in assuming this. By putting a new camera on fully automatic mode including the focussing, this expensive piece of equipment should know exactly what to do.
Not Necessarily So...
Unfortunately this isn't the case. As I said at the start of this chapter:
"No matter how far technology progresses, there will always be a huge element of skill, practice and knowledge required in all aspects of photography".
Tip: When using an SLR to photograph constantly moving objects such as horses at a show jumping event, think about this.
The first shot you probably took of the horse was in the distance as it entered the arena. The last shot could be as it went past you at close proximity.
Now you go to shoot the next horse entering in the distance as he jumps a fence. However, your lens was already focussed at the closer end of its range from the previous shot meaning you miss the next shot. This is because your lens takes time to refocus for the further distance (even half a second is a long time when shooting sports).
So, once the first horse has passed, pre-focus on the general area you wish to shoot next, before the next horse even comes into view. That way your lens will only have to make a speedy and small adjustment. It won't have to "search" for the correct focus, hopefully meaning you get the shot sharp!
This tip applies for all photography with fast moving subjects. Think in advance about where your next shot will be. Set up the focus early giving your camera and lens less to do other than get it right first time.