The Act of Pressing the Button
If there's one key element involved in being a photographer it would have to be the act of pressing the shutter release button. Without that, there would be no image. For such a small button, there's a lot to think about.
One aspect of that button is when to press it. Photographers try to look for that "decisive moment" at the peak of the action, the moment when everything comes together to create the best image possible. Of course there are many such moments. But depending on the subject, there are far more that wouldn't qualify as decisive. Whether it's the wild animal looking the wrong way or the wild flower blowing in a gentle breeze, timing matters.
But even knowing that, it's not easy to get the timing right. The coast is clear, so you press the button. But in the split second it takes you to do so, a gust of wind comes up, or the subject turns its head. Curses, foiled again, you mutter under your breath. And so you fire off another one, and another. If at first you don't succeed, as the saying goes.
Sometimes, you don't even know if you got it or not. At the very moment you press the shutter release, the mirror in a DSLR flips up out of the way, blocking the viewfinder completely. At the moment it matters most, the viewfinder image goes black, and you find yourself blind precisely when the shutter fires. Thank heaven for digital photography. Some may denigrate the act of checking every image on the camera back LCD as being the mark of an amateur, but professionals do it too. How else are you going to know precisely what happens when the shutter fires? You may not really need to check every shot, but when in doubt, I certainly don't hesitate to look. Indeed, the true mark of an amateur is someone who thinks they shouldn't check, or someone who isn't even thinking about the decisive moment in the first place.
When all else fails, it's perfectly valid to fall back on the laws of probability. Take enough shots and they can't all be blurred, can they? Wildlife photographers value camera bodies that can fire machine gun bursts of shots in rapid succession to increase their odds of capturing the decisive moment as their subject moves. Landscape photographers have been known to do likewise as their subject moves. When it comes down to it, it doesn't really matter if your subject is a mountain goat or an avalanche lily.
Another aspect of this all-important button worth looking at is how you press that button. After carefully mounting your camera on a stable tripod, it seems rather foolish to nudge things by pushing on the setup with your finger. It's an interesting conundrum. You want everything to be rock solid and then you go pushing your setup around, even if ever so gently on the shutter release, at the precise moment when it matters most. Doesn't that seem a tad bit contradictory?
In some cases, it is, but in others, it doesn't really matter. If the shutter speed is fast enough, it will freeze motion regardless of where that motion came from. With the shutter open for a brief enough interval, a flowing waterfall can be frozen in mid-fall. And at a fast enough speed you can press the shutter release most any way you want and any induced motion will be equally frozen in time. You could even hand hold your camera while you press the button, if you like living on the edge. There's an old rule of thumb that you can safely hand hold at shutter speeds up to one over the focal length. So with a standard 50mm lens you could/should be able to hand hold up to 1/50 second. Exactly how the "crop factor" of shooting with smaller than "full frame" sensors alters this equation is a matter of dispute, but it's best to err on the side of being more conservative than necessary to be safe.
And if the shutter is open long enough, any small degree of oscillation caused by pressing the shutter release will die down quickly enough, contributing only negligibly to the overall exposure. As an example, if it will take thirty seconds for the exposure and you cause a brief jitter that lasts less than one second, you'll never see any effect in the final image. No image at all will show in that time which is why you set the exposure for far longer. Exactly where the limits are depends primarily on how critical you want to be when viewing your images.
Of course the obvious answer to avoid the whole issue of induced camera shake is to use a remote release. Many cameras use electronic cable releases while others utilize infrared or even radio frequency remotes. Regardless of what your camera lets you use, they all will provide the same benefit. Pressing the button on your remote means you won't need to press the button on your camera. Cabled remotes can be a nuisance since they give your camera a "tail" to drag around unless constantly attach and detach them. Cordless remotes can fail when their batteries give out at the worst possible moment. But both these problems pale in comparison to the frustration of blurred images caused by physically pressing the camera shutter release button.
Some photographers instead use the strategy of using the camera self-timer to delay firing the shutter until any motion induced has had a chance to die down. That can work for cooperative subjects that stay still between the time you they press the shutter release button and when the shutter actually fires. But it can introduce a whole new form of frustration if the wind blows or the wild animal is indeed being wild. I have resorted to this technique, but only if my remote release fails for some reason. Trying to press the button at the best possible time is hard enough without needing to predict in advance just when that time will be.
Hopefully all this will give you something to think about that can improve your photography. With all the effort each of us spend on getting ready to press the shutter release and on processing the images that result from doing so, I thought it about time we spent some time considering the actual act of pressing that button.