How to trigger the shutter isn’t a big topic, but it still needs covering. Obviously, you generally trigger the shutter by pressing down on it fully, and the camera will take one picture. However, most cameras will have different release modes, including the ability to fire off lots of shots in succession, sometimes called “continuous – high or low”, or shown by an icon of lots of pics stacked on top of each other. The speed this can go at is measured in frames per second, and this mode means your camera will keep taking pictures as long as you keep your finger pressed down on the shutter, or until your buffer fills up.
Buffer? What on earth? Well, back in the day when we shot film, you might have a camera that could shoot at 6 frames per second, and that meant a 36 exposure roll of film would be exhausted in 6 seconds, and you’d have to reload. Nowadays, there’s a chance you’ll fill your memory card up, but they’re often so big that it won’t happen for some time. The bottleneck will usually be the buffer in your camera.
If you think about it for a minute, you’ve got a sensor that has however many megapixels, and all their information needs to be gathered, and then written on to the memory card. All of this requires processing power, as well as some sort of temporary memory. This little system is basically your cameras buffer. As a rule, the bigger and better your camera is, the bigger this buffer gets, and the more you can shoot before you camera says “wait a minute, I need to do some thinking.”
Fast, powerful buffers tend to be found in high end expensive cameras, but performance is improving across the board. Their overall performance is affected by how many megapixels you’re shooting with, as well as how fast your cards can write information down. At one end of the scale you’ll have a high end camera with a big buffer, a sensor with something like 16MP, and a fast card, which will effectively just keep shooting very fast for a very long time. At the other, a cheaper camera with a higher megapixel count, and a slow card – a system like this will probably stop shooting continuously after about 20 frames or so, and probably won’t shoot very fast in the first place – something like 3-5 frames per second as opposed to the 10+ frames you might get with a high-end camera.
Some cameras have some form of interaction between the Autofocus system and the frame rate, you’ll need to check your own camera’s manual to find out if this is the case. One thing that should be obvious, having just talked at length about focusing, is that if you’re firing off at 10 fps trying to catch some action, you’ll almost certainly want to be using some sort of continuous focusing mode so that your focus can keep up. This is another place where “back button” focus can be very handy – you’re better able to select when (and where) to focus and when to shoot if the two operations are separate.
Reducing vibrations, and getting sharper photos
Speaking of focusing and frame rates, whilst 10fps is really cool, stop for a minute and think about what’s happening when you fire the shutter that fast. Every time the shutter fires, besides the sensor recording the image, the mirror goes up, and then comes down again. You generally won’t sense this yourself unless you’re very delicate, but the camera will know about it! Think back to what we know about camera shake (and if you need some revision, go back and read up on shutter speed) and you’ll realise that any vibration in the camera is going to contribute to camera shake. You tend not to notice this when shooting at fast frame rates, because such frame rates are often associated with action photography, and as such you’re often shooting with a very fast shutter speed, which of course minimises the effect of camera shake.
If you want the most shake-free, sharp photos, first off place your camera on a tripod, or other support, and use some sort of remote release – the action of pressing down on the shutter can cause more vibration than you might think, and then, if your camera has this option, choose “mirror up” mode. What this does is break the process of taking a picture down into 2 stages. With your first press, you bring the mirror up and with the second open the shutter. This allows you to pause between the 2 so that the vibration caused by the mirror slamming up into the prism fades away. This is ideal for subjects like landscape and still life where time isn’t quite as critical as sports or portraits – the delay it creates in shooting can be quite an impediment if you’re trying to catch a moment.
The Self Timer
Last, but not least, I ought to mention the self-timer. You’ve all probably experienced these at one time or other, usually during a family photo whilst your Dad or Uncle struggles to get the camera in place, then run back to join the family just too late for the shutter to go off. They can be used for this purpose, of course, but they can also be used as a poor man’s “mirror up” mode if your camera doesn’t come with one. As long as what you’re shooting isn’t too time critical, you can minimize any vibrations that might come from you simply pressing the shutter by using the self timer – any movement you’ve added should have faded by the time the 10 second timer winds down, assuming you’re on a tripod or similar of course.
Finally, a self-timer can actually be used as a poor man’s remote trigger. Very early in my career (I’ll give you a clue roughly when – we were shooting a feature that was to tie in with the first Jurassic Park film) the guy who was my mentor showed me a superb trick. He wanted to get a shot from a very high angle above this enormous model dinosaur, but lacked a step ladder or similar. We were able to climb fairly high alongside it, and then he attached his camera to a monopod, put a wide angle on the front, pre-focused on where he thought the dinosaur would be, hit the self-timer, and then hoisted the whole thing above his head, gaining him another 5ft of height, and the shutter fired once the timer had counted down. Genius.