Which neutral density filter to get?

[Muskydave22]

I am wondering which filter to get in order to take some photos durings the day of waterfalls and rivers in motion. Any advice will be appreciated.

Dave

[Quad]

Probably something like

http://www.bhphotovideo.com/c/product/8116-REG/B_W_65066720_67_mm_110_Neutral.html

or

http://www.bhphotovideo.com/c/product/155264-REG/Hoya_018106_67_mm_Neutral_Density.html

in the appropriate size. Assuming you want the silky water effect.

[Dave 1942]

Muskydave:

I use two stop and three stop nutural Density filters. It depends on how much I want to slow my shutter speed down. I also use the same filters in Split ND Filters, both hard and soft stop.

Dave

[argyle]

I am wondering which filter to get in order to take some photos durings the day of waterfalls and rivers in motion. Any advice will be appreciated.

Dave

The strength of the ND is dependent upon the available light at the time, as well as exposure requirements. Basically, for waterfalls, you'd want to get down to about a 1/2-second shutter speed, maybe even 1-second. Too slow, and the water starts to look too much like cotton candy...too many shots like this just look awful, TBH. Then again, it all depends on what you're after.

Typically, choose a small aperture, lower your ISO to 100, compose the shot and take an exposure reading. Determine the amount of stops needed to get down to the 1/2 to 1 second shutter speed...that's the ND filter that you'd need. For example, if you're in a bright environment, set to ISO 100, and your scene meters 1/1000 at f/16, you'd need an 8-stop ND just to get down to a 1/2-second shutter speed. If you happen to be in an area with tree cover or filtered sunlight, you'd be in a somewhat darker environment and need a lower strength ND.

Remember too that a decent polarizer will help you to control/manage reflections, and that it will also serve as a 1 to 2-stop ND filter. For this example, you can stack a 6-stop ND on top of a CPL to get the 8 stops total that you'd need, but you may have to be mindful of vignetting.

You'll most likely need more than a single ND filter. I'd go with a 4-stop and 6-stop...coupled with a decent polarizer, you'd end up with a pretty good range of coverage. There's also a variable ND filter made by Singh-Ray...lets you dial in anywhere from 2-8 stops of reduction. Unfortunately, its only available in 77mm filter size and cannot be used in tandem with a CPL. S-R also has a new version available that has a CPL built into the unit (Vari ND Duo)...either way, both are very expensive (just under $400).

[neilwood32]

Agree with Argyle - thats pretty much the set up i have.

Either of the filters can be used on their own or added together to make a 10 stop and when you add a polariser on top, you have 12 stops - more than enough for almost any circumstances.