When photographing water in motion, choosing the right shutter speed can be tricky and depends upon the effect that is desired. There are 3 "types" of pictures that can be taken of water in motion:
This picture is taken with a shutter speed of 1/60 sec, and is not fast enough to freeze the motion of the water. This picture looks about how the river is looking i real life.
A faster shutter speed is needed to freeze the motion when photographing this close, bur might have been fast enough if the river was just a smaller part of the picture.
This picture is taken with a shutter speed of 1/8 sec. This is usually a good speed to get a natural look of waterfalls, but is a bit to long to look natural in this case.
This picture is taken with a shutter speed of 0.4 sec. It's even more ghost like than the previous image.
Any longer exposure time than this would probably not have changed significantly the appearance of the image.
Shutter speed is important when photographing water in motion, and will play a big role in how the picture will turn out.
Here the effect of using a polarizer when photographing water can be seen. The reduction in reflection and the ability to see through the the surface can be clearly seen. The first image is taken with the polarizer in a an angel that gives minimal effect, and the picture is more or less as seen with the naked eye.
In the second picture the polarizer used with maximal effect, and one can see through the surface.
Which image is the best? I guess that depends on taste and preferences, and the motive of course.
Processing of the images in the workflow in the computer can have big impact on the final image. Sometimes you come home with an image that does not look like you had visualized the image.
The image abowe is the my finished version of this picturev that I'm most satiesfied with, but I had to tweek saturatio, contrast and curves among other tings to get what i wanted.
This is the image as it came fram the camera with only strait raw conversion without any adjustment of the image. As you can se it's rather dull.
This is a black and white version of the picture. Somtimes a image will be best in b/w, but other times the color version is better.
Mirror vibration is usually most notable at 1/8th or 1/15th second, depending on the camera body. The negative effects of mirror slap is less noticeable as you go higher or lower, being essentially gone after 1/30th on the top end and gone by 1/4 or 1/2 sec at the low end.
So as a rule of thumb, avoid 1/8th and 1/15th like the plague unless you use MLU.
With a digital workflow many special effects filter can be recreated in PS instead of using filters during capture, but there are still some filters that can't be added i PS and that must be used during capture.
The effect of using a polarizer is one thing that can't be easily simulated i post production in PS. The polarizer removes reflections, and saturates colors.
IR-filters cut visible light and lets through only IR light. The effect can be mimicked, but that is not a substitution for the real thing.
A neutral density filter is called "neutral" because it doesn't affect the colours in your photo. Its purpose is to reduce the amount of light reaching your camera's sensor. This is usually used to get longer exposure times. NDs come in different standard strengths as well– 1 stop, 2 stop, all the way up to 10 stops (and beyond.)
Graduated ND filters are generally used to darken a background that’s significantly lighter than the foreground. Common examples are sunrises and sunsets with bright skies and foregrounds in shade or mountain scenes where a snow-covered mountain is much brighter than the foreground.