[Michael Piziak]

What # ND filter is good for waterfalls. I know they come in 2, 4, 6, 8, 10 etc....

[tuco]

The time of day is a factor. With a rapidly moving waterfall you only need a few seconds. More if you really want a blur. So at dusk/dawn you could get by with less than the middle of a sunny day. The Hoya NDX400 ( approx 9 stop) has less color shift than the B&W 10 stop. So get either a 9 or 10 and you should be good-to-go.

[mattt]

I carry a ND8 and an ND400... 3 stops for slowing water to 1/30s shutter or longer. The ND400 is good for making 5s - bulb exposures for that streaking sky effect.

[jrpower10]

Here's a follow-on question. How do these types of filters compare to Lee filters, such as Lee's Big Stopper? The screw-in certainly have to be more convenient but I'm curious about whether image quality is better with one over hte other. Also, I assume you can use step-down rings for smaller filter threads rather than buying multiple filters, but this may interfere with some hoods.

[Michael Piziak]

What about these variable ND filters that go from ND2 to ND400
I assume that they are 2 polarizers built into one filter that you turn and it gets darker and darker

[narual]

What about these variable ND filters that go from ND2 to ND400
I assume that they are 2 polarizers built into one filter that you turn and it gets darker and darker

That's exactly what they are. They work pretty well, though sometimes you get uneven darkening when you get close to the darkest setting -- it ends up having a sort of rounded X shape that's a bit darker than the rest.

I think it's worth having one of those in your bag even if you want to get dedicated filters as well. It's a lot easier to throw that when you're moving from bright light to shadow and adjust that than it is to keep changing filters.

[c.a.m]

I just went through the process of choosing an ND filter, to be used mainly for taking pictures of flowing water and also to allow me to open up my aperture for shallow DOF in bright conditions.

I considered various options, including different sizes for my lenses, fixed-ND and variable-ND filters, and various brands. One of the main considerations for me was to be able to use the filter on my DA 15 Ltd, which drove me to choose an exact diameter (49 mm) rather than a larger size plus a step-up ring, which could induce a vignetting effect.

I chose a Kenko Pro1D ND8 filter (3 stops). It worked well during my first outing - taking pictures of fairly fast flowing spring run-off streams. I found that it worked well at speeds of about 1/4 to 1/2 second. Conditions were cloudy or partly cloudy, mid-day. I also used a CPL filter to control unwanted reflections from the surface of rocks; the CPL introduced an extra 1-1.5 stop darkening.

I opted for an ND-8 to allow flexibility in the future. If or when I find I need additional stops, I'll get a 6-stop filter, which will give me a 3-, 6-, and 9-stop kit.

I chose Kenko because it is good quality (comparable to Hoya) and available on the shelf locally.

- Craig

[MJSfoto1956]

variable ND filters work well with normal to telephoto lenses. The trouble is when you start using wide-angle lenses the disturbing "cross hatch" patter reveals itself rather early. So while you might be able to get 6-8 stops with a 70mm lens you will likely only get about 3-4 "useable" stops with a 24mm lens. This is from my experience with couple different models of variable ND filters, and they all basically have this problem, some more prevalent than others. Lately I've been moving more and more to packing three ND filters: 3-stop, 6-stop, and 9-stop (as well as a CPL of course). The 9-stop will require you to first focus without a filter, then attach the filter then finally take your shot. I find I can use AF with the 3-stop pretty reliably without needing to remove the filter. The 6-stop is hit-or-miss depending on the current amount of light.

YMMV

Michael

[narual]

Odd. The cheapo 77mm one I bought for my 10-20mm worked fine without showing the X pattern. The 49mm one I bought for a few older lenses showed it pretty badly regardless of which lens it was on. I haven't tried it on the 15mm yet, since I got that in late fall and haven't had a whole lot of sunny days when I was taking pictures since then.

I haven't seen it happen on the one I got for my f1.2 lens, but I've never turned it up very high with that.

[reeftool]

The 49mm ND400 from Hoya works fine on the DA15 although using a 9 stop ND filter for low DOF shots on a fast lens isn't easy. 9 stops is as dark as a welding helmet.