One question I get a lot is how to get your subject sharp and perfectly in focus, even when they are moving. This can be tricky, especially if your subject is a child - the movements tend to be more erratic and therefore harder to pin down! (Not to mention the fact that they don't take any instruction, grrr)
However, if you follow some simple tips, you should increase the number of "keepers" you get - so without further ado, here's my tips for taking sharp photos of moving subjects..
1) Make Sure Your Shutter Speed is high enough
First of all check your shutter speed. With moving subjects you need an absolute bare minimum of 1/125 but you will want to go even faster than that depending on how quick the movement is, so this could be 1/500 or even 1/1000. Always make sure that your shutter speed is high enough - if in doubt, go higher.
2) Use a Smaller Aperture
It's definitely better to use a higher F stop (smaller aperture) as you will find it much easier to nail focus on your subject. That wider depth of field means you don't have to be quite so precise with your focus - it gives you that bit of wiggle room which is essential for capturing movement. I appreciate that it can get tricky as you have a smaller aperture, and a high shutter speed which are both letting less light into the camera. so you will probably need to boost your ISO higher than usual. (This is why it is also easier to capture any fast moving action shots when there is plenty of light around!)
3) Use Al Servo / Continuous
For moving subjects, Al Servo / Continous is the best mode, as this mode constantly refocuses whilst tracking your subject. Al Servo works by trying to anticipate movement and works brilliantly for subjects following a line - for example a bird in flight or a runner as they move forward. It finds it a bit harder with subjects that move erratically, but it still will constantly try to find focus, so you should find that your chances of getting a sharp subject greatly increases!
To use, select AF mode, then choose Al Servo (Or AFC for Nikon) and half depress the shutter to start the autofocus, and keep your finger half depressed until you are ready to take the shot, when you would depress the shutter fully.
4) Try Back Button Focus
Some people love back button focus, others hate it, but it might be something that you find useful, particularly when dealing with moving subjects. Back Button Focus is simply assigning another button on your camera to lock focus, rather than having to half depress the shutter - this way you can keep your finger on the focus button, whilst simply using your shutter to fire off shots. You can read more about it, and how to set it up on your camera on this post on back button focus.
5) Follow the Subject with the Viewfinder
If your subject is moving across your frame (as opposed to moving toward you) you should also aim to follow your subject with your viewfinder - the subject's speed across the frame causes motion blur, and you can minimise that simply by "panning" along with your subject.
6) Watch your motion.
If you are swinging the camera about erratically whilst chasing your fast-moving child, you are adding your motion to the mix which is not a good combination!. Try to keep your movements smooth and fluid (easier said than done!) whilst following the subject. Lock your elbows in at your side to further steady the camera.
7) Upgrade from the kit lens
- The quality and type of lens you are using also makes a difference. Some lenses are simply faster to focus than others. The 50mm F1.8, whilst I love it and it is absolutely a brilliant lens for the price, it does not focus terribly quickly, so it's not ideal for fast moving subjects. If you take a lot of fast action photography, you might want to upgrade your lens. Please note that's not to say that you can't get a sharp photo with a kit lens or a 50mm F1.8 though - you absolutely can - just that you will find it easier with a slightly better lens. (You can also read my tips for using the Canon 50mm F1.8 here!)
The good news is with a digital camera this is pretty much free! Practice with the modes, and with following your subject, and even give back button focus a try! Please note that you will never get ALL your shots of moving subjects tack sharp - probably not even close, but these tips should up the "hit" rate!
If your subject is stationary, then you need to focus a little differently - here are my tips for getting sharp photos with still subjects.