Hi Stuart…
Waterfalls are popular subjects for many photographers but as you are discovering for yourself, timing is everything; if you show up after a week of rain then chances are they will look spectacular, but show up during a dry spell and most waterfalls will be a disappointment.
Given that you are new to photographing waterfalls I would suggest that this is not a bad attempt. I notice that you used two Neutral Density filters stacked on top of each other (an ND4 and an ND8) to get the exposure time down to 18 seconds. It may have been better to just use the ND8 filter. Ideally you want to limit the number of filters that you have in front of the lens because these can ultimately degrade the image with softening and internal reflections on the glass surfaces. Aside from that, I am uncertain you would notice too much difference between an 18 second exposure and a 5 second exposure in this situation.
What concerns me about this image is the very tight cropping. Tthere are times when tight cropping can be a good thing, but it is usually when you are looking to explore patterns or details within a subject. With this image you could have cropped in really tight (like removing another 80 percent of the image) just for the sake of capturing the veiling in the water near the top of the falls. There are times though, when you are better off allowing some breathing space around an image.
From your message I know you cropped this image tight to remove an area of dark shadowing on the left of the image but the fact is, that shadowing might have provided more real estate for the image to breath in. It might have also provided some good visual balance to this photograph; balance is an aesthetic tool that can work in a variety of ways, but in this instance it would have given the viewers eye an opportunity to move away from the bright water, indulge in the greenery for a moment and enjoy some darker shades before going back to the bright light again.
Now, there is one thing that you can do to improve this image as it stands at the moment. If you look at the original image you cannot help but feel like the top of the picture is level but that the bottom of the image is tilting off to the left. Open the image in Photoshop (or you can also do this in Adobe Camera RAW) and then go to the Lens Correction Tool. In this filter option you will find the Auto Correction control (used for automatically correcting known distortions in lenses), and the Custom setting (used for correcting geometric errors). In the Custom panel, go down to the Transform box and move the Horizontal Perspective to +10 and then shift the Angle by +0.50 degrees. Click OK, then crop the image to remove the empty sections of the image. The bottom of the image is now level.
Cheers, Anthony
Forest Cascade - Image Doctor's edited version
