One of the things I've been developing over the last 6 or more months is a more creative approach to the use of shutter speed. Rather than a 'short' or 'long' binary switch, I like to consider shutter speed as an analog dial allowing us to dial up or down the degree of detail in the water to taste and to suit a particular shot. I particularly love the streaking that gives the water a sense of personality when using a mid-length shutter speed of 1 second plus or minus 2/3 second.
Though it suits some shots, I think full detail in the water often provides a confusing and distracting element in a frame. Conversely a very long shutter speed pushing the water exposure towards white for the 'silky water effect' removes any sense of character in the water, it just becomes white blobs in the frame. In between the two though there's the possibility of retaining some of that detail, that real sense of flow and undulation.
I often wonder why, when presented with raging torrents and stormy seas, we want to tame them into placid milky foam. In these elemental environments it is precisely the raw power and personality of the water that I want to capture. If it's a raging torrent, let it be so!
I thought I'd share an image from Glen Sligachan to show you what I mean.
Here's the first shot, looking towards Marsco down Glen Sligachan and the raging torrent that is Allt Dearg Mor (the one the footbridge crosses). Not a unique shot, indeed quite popular though most tend to shoot towards Sgurr nan Gillean and the Cuillin Ridge rather than Marsco, which I think is a particularly photogenic mountain. Still, I find it impossible to drive past Sligachan without stopping such is its beauty.
Already aware that I prefer to avoid very long shutter speeds these days, this shot was made at 1.6" at f/16 and ISO100. I had a polariser and a 3-stop neutral density filter on, the combination of which will block out between 4 and 5 stops of light. It's quite a nice shot I think, but when I look at the water it feels too placid. In particular, the white of the plunge pool holds very little detail and as a result interest. It's quite a large expanse of an image to be close to white and unsettles me.
Note that with other more gentle cascades you may find that 1.6" would retain reasonable detail in the plunge pool. Conversely with a large crashing waterfall, even 0.5" may record too much foamy movement in the plunge pool to keep any detail. The point here is that each time you encounter water you need to use some judgement and spend some time getting to know it to choose the perfect shutter speed. Each shot has a perfect shutter speed, but it's not fixed it's something you have to discover.
For the next image I've pulled out the 3-stop ND filter and I'm now using a 1/5th shutter speed. Note that in so doing I've nudged my polariser and there's a lot more glare on the rocks - oops! This is the main reason I often use a polariser around waterfalls.
Looking at the water itself there's a lot more detail in there and so to me sense of motion through the frame. Let's inspect more closely side-by-side.
The overall feel of the water in the shorter exposure is much more like what I would associate with a turbulent pool and a raging river. Observe that the exposure is still long enough that the detail has been 'smeared', so we don't have the full detail but rather the implication of detail.
Unfortunately the shorter exposure was just a tad under exposed, and the glare on the rocks from that nudge on the polariser means I'm not fully happy with this frame as is. Instead I take both exposures into Photoshop as separate layers (in Lightroom, select both, right click, "Edit In", "Open as Layers In Photoshop") and I use a layer mask to 'paint in' the more detailed water. You may also note that I've dialed down the opacity of the layer with the water exposure to 53% to reduce the extent of the detail in the final frame. Actually having a separate exposure like this allows me to dial the detail up and down as suits my taste back in the studio.
There's a few more tweaks I've made elsewhere in the image to result in the final image below. Some may prefer the original, smoother version but I much prefer this more turbulent rendition of Allt Dearg Mor and Glen Sligachan; for me it better suits its wild feeling location.
