Just like with shooting motion blur and panning, the purpose of stop-action photography is to denote movement of some kind. Where the former will allow you to get a feel of the fast speed at which a subject is moving, the latter will act like seeing in slow motion.
You can see all the detail that is otherwise lost by the human eye, or brain, that can’t really process more than a blur at anything that requires a shutter speed of 1/60 or faster to be captured as a freeze frame. Even at 1/30 there won’t be a noticeable difference. This is why film really only needs to be shot somewhere between 24 and 30 frames per second — with the exception of shooting for slow-motion. For several theoretical reasons I won’t get into right now, it is what will appear most natural to the eye. It’s also the reason watching something shot at 60 fps can be a bit nauseating.
Notice that when you wave your hand in front you, motion blur appears as a trailing or ghosting effect as you try to keep up with the movement. You would likely need something faster than 1/60 to capture your waving hand while avoiding motion blur.
The same goes for any moving subject, and you will have to determine through trial and error what shutter speed you will need for anything you are shooting. You can likely freeze-frame a dog running or jumping with just 1/250, but to capture a hummingbird in flight you might need to go up as far as your camera will allow — even then, between 1/2000 and 1/8000 you might not get a fully frozen frame. The same goes for a fly. The one below was shot at 1/4000. There is still motion blur on the wings.
Then there are the other factors that complicate getting the correct exposure. With a faster shutter speed, less light will be allowed in and you will need either a larger aperture or a higher ISO to get the shot. The larger aperture will cause a shallower depth of field which makes it harder to focus on the subject. A higher ISO will cause extra noise that will degrade image quality.
Thus, the key to good stop-action shots is having enough light. Longer days in the summer months mean more and brighter natural light to work with, but a studio setting with strobes will work just fine. You will want to use the fastest possible shutter speed you can get away with considering your light source.
This chimp was swinging around pretty fast on those bars at Gladys Porter Zoo. This was shot at 1/4000. (BTW: Shutter speed numbers are just fractions of a second, so that means 1/4000 is just one-four thousandth of a second, or one part of a second divided by 4,000 times. yeah, maths.)
The next important thing to remember is to pick a subject in which you are clearly freezing action, such as, something running or caught midair. A car moving along a road taken at a very fast shutter speed might just look like it’s parked. In that case you might be better off panning or allowing motion blur for that shot.
The cars appear to be parked in the middle of the streets. Not a good way to depict motion. Below the motion blur gives you a feel that the ambulance is in a rush to get somewhere. It’s all about context.
Focus & Focal Plane
Manual focus will be best to use in some cases, but auto focus might work if your lens is fast enough and your subject isn’t moving toward or away from you. For example, a subject running in a line parallel to you will continue to be on the same focal plane (the area in focus) as it passes by, but a subject running to you or from you will keep needing focus adjustment as it gets closer or farther.
With manual focus, anticipation of where the subject will be at the time the shutter goes off is a matter of trial and error. First set your focus, then take the shot when the subject enters the focal plane.
You don’t necessarily need to use burst mode to get the right shot. It might be better to time it yourself. Burst shots might actually make you miss some of the action because the camera might need a few seconds to recover for saving the images before allowing you to take more. You will also just fill up your card with a lot of bad duplicate photos you won’t want to keep. Essentially, you lose control of what you are shooting by letting the camera do the work. Considering you can’t always have access to the most high-end camera body able to shoot fast enough to capture absolutely everything, it’s best to just get the hang of doing it manually. Some cameras can only do a 3 photo burst and take a long time to recover. Meanwhile, you already missed all the action.
In the Studio
Using strobes can be a useful asset for staged shots, such as this below, but timing is still essential.
To shoot something like the photos above, without the help of an assistant or even a remote shutter, you have to shoot in a completely dark room with a long shutter speed like 5 or 10 seconds or however long you need to coordinate the action and setting off of the flash.
In that case, I set up my camera on a tripod and focused on the area where the brush would be dropped. Then I used a Canon 580EXII flash that I set off manually by pressing the pilot light — which is also a button — as i dropped the brush into the water while the camera was doing a 5 second exposure.
There is also a high speed sync setting on an external flash that you will need to know how to use to get shots faster than 1/250.
Usually, when the flash is not directly connected to the camera’s hot shoe either directly, with a cable, or with a wireless trigger kit the high speed sync won’t work and you are stuck with that max shutter speed or with your flash on your camera’s hot shoe where it may not be in an ideal position for lighting your subject the way you want.
If you do manage to set it up, you can get shutter speeds as fast as your camera will allow.
Another thing you can use your flash for is fill light when shooting in natural light. It can give you the extra boost of light you need to get faster shutter speeds if you are shooting as the sun is rising or setting.
Overall, shooting fast-moving things can be pretty challenging, but when you do capture the perfect shot it will be more impressive. Just remember WHEN you should choose to use a fast shutter speed and when to choose a slow shutter speed to depict motion.