My wife and I went to the base of Tews Falls along the Niagara escarpment - a process which involves wading through a shallow river. To get this shot my tripod and I were up to our knees in water. My first time using ND filters - don't know if I overdid it. Just because you can get 20s exposures during the day doesn't necessarily mean you have to. This one was 3.2s @ f16. C and C appreciated - only posted here a couple of times. I may try a B+W conversion on this as well.
Interesting comp, effective with how the light falls on the image. I agree with Mike, I think you could lighten up the back a little - but make sure to keep the contrast nice in the water there (don't want it getting gray). I too think it's a little cottony - too long a SS. Personally, I like retaining some texture in the water, that usually works best between 1/13th-0.3sec exposures, depending on the water flow.
Pretty cool stuff. I like long shutter speeds on water, so it looks great to me... What I do agree with some of the others on is the back of the shot being too dark. Did you bracket? I do like how you were capturing a spotlight of sunlight on that pour off area. Sometimes it's also a matter of timing as to how the light spreads across an area. It does look pretty good though.
On the 2nd one, it looks nice too, what an interesting looking waterfall. You maintained the highlights in the sky really well, and balanced the exposure just right. Only part of the composition I don't like, is that little bit of white water at the lower left corner, it really draws the eye to that area instead of letting the eye enjoy the falls, so I would clone or crop that bit out.
Good job on playing with the ND filters, as you said just because you can take a 20 sec exposure doesn't mean you have to. For my silky water, I have found an exposure in the range of about a second works best. But to each their own on that..
What I do agree with some of the others on is the back of the shot being too dark. Did you bracket? I do like how you were capturing a spotlight of sunlight on that pour off area. Sometimes it's also a matter of timing as to how the light spreads across an area. It does look pretty good though.