Why Graduated Neutral Density Filters are important

I can't recall how many times I shot a scene two or three times at different exposures because the dynamic range was too wide. When you shoot a scene multiple times at different exposure (exposure bracketing), you ideally need a tripod but you don't always have one so you end up with a blurred picture or no picture at all.  This is when graduated ND filters come handy. Why? Because they help you squeeze the dynamic range within the boundaries of your histogram. It, of course, depends of the scene and the light but let's says you are shooting a typical landscape scene. With high-performance sensors that we now have, it is possible to capture a wide dynamic range provided that most of the range fits within the range of the sensor. When you have all or almost all of the dynamic range contained within your histogram or your sensor limits, it becomes realistic to take one picture instead of two or three. Here is a graphical explanation of what I mean.   

Here is a histogram showing a very wide dynamic range. Actually, the blacks and the whites are clipped, which is usually not good. If a scene shows this kind of histogram, I would be tempted to use my tripod and shoot three shots at different exposures, but what if I don't have a tripod?

I always have my graduated ND filters in my bag, so I'll use them! In this case, I might use a 2 (0.6) or maybe a 3 (0.9) stop graduated ND filter because my goal is to not only bring the whites back in the safe zone but to also have room to bring the blacks back in so to have more details in the shadows. The graduated ND filter will bring the highlights towards the centre of the histogram and prevent them from clipping:

In the example below, you can see that thanks to my graduated ND filter, the highlights are now in the safe zone thus leaving me with a bit of headroom to maneuver (notice the space at the right-hand side of the histogram). I will that headroom to push the blacks in (which means I have to leave my shutter opened a little longer), thus recovering details in the shadows.   

This is a very rough explanation of how you can use a graduated ND filter but this will not work in all situations. It is a case-by-case scenario. You may sometimes have to lower the shutter speed quite a bit, sometimes to the extent that it will cause your picture to be blurred. It is a trial and error process. Fortunately, I'm a happy Fuji XT-1 shooter with a 5-axis stabilized lenses which enable me to shoot handheld at very slow shutter speeds. Having a 5-axis stabilized camera body or lens is a blessing since it dramatically increases your chances to shoot more better pictures without a tripod.