Great shots, especially for a first time! I'm only an amateur but I photograph waterfalls a lot (favorite subject); here's my general advice for waterfall photography:
-WIND is a huge problem for long-exposure waterfall photography; you may not notice it until it's too late... keep an eye on moving branches, grass, plants etc. that will blur in the image; you can usually wait for a calm moment in between breezes to take your shot
-Try out a circular polarizer (by itself or stacked with ND filter)
-Experiment with different lighting situations, not just shady or cloudy; try diffused sunlight (thin clouds), golden hour, etc.
-Keep an eye on the white balance, it is particularly tricky for waterfalls; most waterfalls are realistically white in color but others may be slightly blue, turquoise, etc. If you want your pictures to match the scene as accurately as possible (and be believable), take note of the color of the particular falls as you're photographing it and shoot RAW
-Change perspectives, especially higher/lower with your tripod, to see what you can get... it's tempting to always want to shoot down low, but for many waterfalls pushing the tripod up to 6-7 feet tall can show off certain waterfall patterns
-If you're going down low, you may need that f-stop pumped up high (sometimes I go up to f/18 or even f/22)
-Always experiment with different shutter speeds if it's your first time at a particular waterfall; you'll be surprised how some falls look better with fast shutter while others look better with slow (or ultra slow) shutter
-Always take multiple shots of each perspective and/or check shot on viewfinder; things like to go wrong w/long exposure (bug flying by, wind, etc.)
-Exposure is tricky -- overexpose and your water will lose detail; underexpose too much and noise will increase; don't rely too much on meter, use your best judgment and perhaps bracket a little just in case
-If you have the lenses, experiment with different focal lengths (back up and use longer focal length instead of just wide angle)
My advice based on many years of photographing lots of things -
If you can afford it, I would get a 1 stop, 2 stop and a 3 stop ND filter to start. I find that I make most use of the 2 stop and the 3 stop, but the 1 stop is handy to have to give you a 4 (3+1) stop if you need it and, of course as a 1 stop filter. Again, don't just buy the cheapest ones you can find as they are usually not good glass and some of them will give your images a color cast.
I have Hoya HMC filters and have never had a problem with the results that any of them give me. Shop around as you will find prices will vary and check out websites like
B&H and 2Filters. If you have a strict budget, then buy a 3 stop first, then a 2 stop, then a 1 stop. The other decision you have to make is whether you go for "screw -on" or some form of square filters. I have both (I bought the square ones to get graduated ND filters), but I find I use the screw-ons a lot more as the square ones require a holder and an adapter for each lens size and are more expensive. For the circular screw-ons, I bought filters to fit my largest lens, an 82mm wide angle and then bought a step-down ring (or step-up as some folks call them) for my 77mm lenses. This ring screws onto the 77mm lenses and then the 82 mm filter screws into the ring, allowing the 82 mm filter to be used on the smaller "lens". This way, I have most of my lenses covered with 3 ND filters and I do not have to buy a filter for each lens whose objective diameter is different.
Hope this helps, but ultimately what you decide to do should be whatever is best for you.
WesternGuy
WesternGuy,
I have a question for you since you have many years of experience of photographing silky water shots. As you can see from my photos, they have blue hues, the longer the shots last, the severe the hues are. How do you correct them in the post? Thanks!
Could be a result of the filter you're using, lighting, white balance, or other factors. Easy way to fix this in post:
-Shoot RAW and adjust white balance (warmer); sometimes putting the eye-dropper over the water works, but only sometimes
-Reduce the saturation of blue (and possibly aqua) tones in the water