The title of this blog post begs an answer, what is the most important button on your camera? The answer is easy, the shutter button! The question is, do you treat it that way?
Most modern digital cameras have at least a dozen buttons, and that is wonderful right? Sure it is, but at the end of the photo making process, once you've figured out all the technical aspects of taking a photo, the only button that matters is the shutter. How do you use this key button on your camera? Do you mash away, getting as many shots off as quickly you can? Do you gently press it to reduce camera shake in low light? The answer to those questions will show up in your photos. If you crash your finger down on the shutter, especially at slower shutter speeds (1/50s or longer) you might notice that many of the images captured have some blur. At higher shutter speeds (1/125s or shorter) that might not be as much of an issue, unless you are using super telephoto lenses (the higher the magnification of the lens the more noticeable camera shake will be).
Learning to press your shutter button in a way that reduces camera shake can greatly improve your ability to capture still subjects in low light situations. Yes this is true even if you are using image stabilized (IS, OS, VR etc) lenses or have a camera with built in image stabilization. Are you used to just resting your finger right over the shutter and pressing straight down when you are ready to shoot? If you are, watch closely and you'll notice that your camera will shift slightly as you press down. That is the primary way camera shake/blur is introduced into your images. On Nikon (and some other) DSLRs there is a small lip on the front edge of the shutter button, which can help with this process. Here is a tip that might help with that; rest your trigger finger (as I like to call it) on the lip in front of the shutter and when you are ready to capture the image, slide it down onto the shutter. * Doing this will greatly reduce or if done carefully, eliminate the shift that can take place if you simply push down.
* Canon DSLRs tend to have the shutter button sloped at a greater angle, and don't have this lip on the shutter. The greater slope allows the user to rest their finger in front of the shutter, creating a similar effect to that of the lip. If you rest your finger in front of the button, simply slide your finger back towards the shutter softly to depress it.