ND Filters

Looking for some recommendations on ND filters. The primary use will be to take longer exposures of rivers, streams, etc in bright lighting. My primary question would be how much reduction should I get? Or am I best off with a variable ND filter?

Sambisu

I'd recommend looking at the exif data of shots similar to what you want and then count how many "stops" you are away from blurring moving water (typically 1/4 to 3 seconds) or smoothing water (15 secs to a minute plus).

My experience is that you need ~2 stop ND to blur moving water in the shade, ~4 stops on cloudy days, and 6-10 stops in direct sun. To smooth water you are typically looking at 10 stops.

I've been tempted by the variable ND filters but use and really enjoy my 6 and 10 stop screw-in filters from B+W. I use my CPL for 1.7 stop ND. If I were to get a variable ND I would likely try the Singh ray vari-n-duo.

I probably use my 6-stop filter the most, but I had to pick just one, I'd probably get the 10 stop ND.

Good luck.

I prefer regular ND filters rather than variable and use both the screw in type and the 4x6 Lee type filters. There are those on the site that use variable that will recommend some to you. The variable might be the cheapest way if you are just playing and experimenting and don't want to spend 100's or 1000's of dollars on filters.

I use B+W filters and have several different stops up to a 10 stop filter. There is no right answer for which one is the right amount of stops as it varies by how much light you are trying to shut out. You start out by shooting at smaller apertures like F/11-- f/16 etc to get the longer shutter speeds. You shoot at ISO 100 to get a longer shutter speed. Then you add the ND if you need slower still, which on a bright day you may still end up with 10 stops.

If I do not have one that has enough stops I stack them, use a CPL with them etc....

If you go with a system like Lee's you can stack several with no problem.
If you go with screw on filters and stack then you have to take vignetting in to account. A suggestion to avoid this is to use a step up ring and get your screw in filters a size or two larger than you need.

Circular I own a 3,6 and 10 stop filter and they have served me well. I paid about $325 for them several years ago. You could buy a variable filter for less than half that.

this might help

http://www.naturephotographers.net/a.../dw1108-1.html

I have 3-stop and 10-stop solid ND filters from B+W, and those meet my needs. I can stack a CPL on the 3-stop for ~1.75 more stops.

As mentioned above, there are both screw-in types and regtangular filters. For solid NDs, I prefer screw-in. The reason to go with the rectangular filter holder setup is for graduated NDs, where a round filter is not ideal (no choice for where you put the dividing line).

It has already been said that the CPL will drop your light an extra 1.5-3 stops, but I wanted to emphasis that you should assume you will be using a CPL with moving water. The CPL takes care of the annoying glare you get on wet rocks which IMO wrecks any waterfall or moving water pictures (and it throws your metering off a bit). On top of the CPL, I use a 3 or 4 stop ND. That works the majority of the time unless you have direct sun light reflecting off white water. However, if you have direct sun light reflecting off white water, it is going to be tough to get a good exposure of the surrounding shadowed areas if you tame the white water enough to blur. For me there seems to always be shadows around rivers and waterfalls because the tend to be in wooded areas. Shaded areas and overcast days will be your best friend... direct sun light is really tough for the camera to handle unless you can get everything in the shot lite up the same (no shadows).

I have a B&W CPL and a cheap ND. The cheap ND can be annoying because of flare problems. Don't go cheap if you can help it.

Was just thinking of making a similar thread to this as I plan on buying a CPL and an ND filter once I get my 100-400, they'll both work on my 11-16 as well. Glad I stumbled across this, great info guys! Thanks!