yesterday I went outside my town, and tried to picture waterfall. On my Nikon d5100 (18-55) settings was:
ISO=100, Aperture=f/25, Focal length=18mm
I wanted smooth water on my picture, but when I set shutter speed 6 seconds I get too exposed? Maximum value of shutter speed was 1/5 of second, to get well exposed picture. I didn't get what I want, because water was not so smooth as I expected. Obviously I have a problem. For example, if you look this picture, exposure time is 30 sec, and picture is not too exposed. How he did this?