Which Neutral Density Filter?

[Sam]

I know this is a very subjective question, however I am hoping for any advice you have to throw my way.

I am going to purchase a ND filter but I am not sure if I should get the 2x, 4x, or 8x. Is one of them a more "general purpose" ND filter? My main motivation is all of the nice looking waterfall pictures I have been coming across but there have been more than a few times I would have liked to have one of these in my bag for other situations. If you have any experience with these please let me know what I would get the most mileage out of. I have decided the brand so it is just a matter of the level.

Thanks in advance for any help.

[iwatkins]

Well, if I had to get only one, I would go for a 4x. Sure, it might make it so dark that you need to expose a shot longer than you would like but it would be worse if you got a 2x and that wasn't enough. :)

Cheers

Ian

[DocFrankenstein]

Never used one yet, but for falls I'd use 8x

[ohenry]

If you only have one in your bag, invariably it will be the wrong one. There is not a good answer here because each lighting situation will call for a different need. The Singh-Ray variable ND filter is a very good answer, but comes at a cost of $340 (albeit it's an awesome filter!). A cheaper solution might be to consider Hi Tech or Lee graduated ND filters and a Cokin filter holder. By sliding them down so that more of the ND portion comes into play, you achieve the same effect. The advantage being that you can use several together to vary the light as needed.

[PacAce]

I know this is a very subjective question, however I am hoping for any advice you have to throw my way.

I am going to purchase a ND filter but I am not sure if I should get the 2x, 4x, or 8x. Is one of them a more "general purpose" ND filter? My main motivation is all of the nice looking waterfall pictures I have been coming across but there have been more than a few times I would have liked to have one of these in my bag for other situations. If you have any experience with these please let me know what I would get the most mileage out of. I have decided the brand so it is just a matter of the level.

Thanks in advance for any help.
As others have stated, there is no one good answer to your question. What ND filter you need depends on what you want to use it for. Then you have to do a little bit of calculating to come up with the ND that will suit your need.

For example, let's say that you want to shoot a waterfall picture. It's a sunny day and the waterfall landscape is fully illuminated by the sun. Using the Sunny-16 rule, at ISO 100, you would need a shutter speed of 1/125 at f/16. But you want to capture the flow of the water by keeping the shutter open for a longer length of time, say, 1/15 of a second. That's 3 stops from 1/125 of a second so you'll need an 8X ND filter to achieve that. Or, you can use the 4X ND filter if you close down the aperture to f/22. (I hope I got the math right but I'm sure someone will chime in if I didn't :) )

As you can see, selecting an ND filter is not an arbitrary choice if you want to use it for a specific application to achieve a specific result.

[robertwgross]

I do not normally carry any neutral density filter or graduated neutral density filter around with me. So, if I suddenly come upon the waterfall, I will put on my circular polarizer, then crank the ISO down as low as it will go, and then have the camera on a tripod.

That generally slows the water into silk for me.

---Bob Gross---

[PacAce]

I do not normally carry any neutral density filter or graduated neutral density filter around with me. So, if I suddenly come upon the waterfall, I will put on my circular polarizer, then crank the ISO down as low as it will go, and then have the camera on a tripod.

That generally slows the water into silk for me.

---Bob Gross---
Bob has a very good idea there. As a matter of fact, if you have two polarizers, you can attach them in tandem and you have yourself a variable density filter just by turning one of the filters while keeping the other fixed.

[robertwgross]

Bob has a very good idea there.

Been there. Done that. Read the book. Saw the video.

---Bob Gross---