Neutral Density Filters

[JAS_Photo]

There probably is already a thread but I don't think we have had a good discussion on and when to use them and how much/many to use. Can a COPL be used instead in some cases? Can you use ND's at twilight? I know that Darwin Wigget uses them to intensify colors in his scenics. Discuss.

[Bambi]

ooh, let get my popcorn and sit back and watch! (and learn of course)

[kat]

I have one ND filter (4). I use it during mid day sun for certain shots that need more than what a polorizer filter can do. Great for slow shutter speeds. I don't use it too often though. Maybe this will give me more reason too.

I think if anything I would use a gradual ND filter more, can't wait to get one!

[Mad Aussie]

I've never gotten around to getting any ND filters yet but they are next on my list. I'd like both ND and GND (Graduated) filters.
Certainly the CP filter will help when a ND isn't available but I wouldn't say it's a great substitute. It just isn't the same thing.

When to use them is fairly simple ... when you have the need/desire to use a slower shutter speed but can't attain it with the settings you need due to the scene being too bright.

How many to use really again is similar to my answer above, but by stacking a couple of them (tends to produce vignetting on wide angle lens) you can vary the amount of leeway you want.

No problem using ND's at Twilight or even after dark if you want. In fact ... that's some of what I want to do with them.

[JAS_Photo]

The next big decision is which type to get once you have determined that is what you need. If you use the type with the holder vignetting should not be a problem I would think.

[Mad Aussie]

I did look at the Cokin system when I got my camera's but it's a bit bulky ... certainly easier to use though. Not sure on the vignetting but I'd think it still would on a wide angle lens. Perhaps not if the filter is wide enough itself.

[zenon5940]

... I know that Darwin Wigget uses them to intensify colors in his scenics. Discuss.

This is where I would really like to know how these filters would help.

Good idea Raiven for this new subject.

[Mad Aussie]

This is where I would really like to know how these filters would help.

Me too as I thought 'Neutral Density' was describing that they don't change colours in any way.
The only thing I can think of is that in the brighter areas they allow a better exposure so it results in better colours there.

[kat]

I'm going through photos now to see if I can get an image up that ND was used. If you would like I can get examples of used/not used... but I only have the one ND. So it will be with just that. I can also throw in the CPOL and see what the difference is with that?

[tirediron]

ND/G-ND filters are, IMO, essential elements in the toolbox of any outdoor photographer. If you don't have any, I would recommend starting with G-NDs vice regular NDs as I feel they have more application. The Cokin 'P' series is the best way to go in terms of compromising cost vs. quality. Certainly if you can afford to pay $150+ per gel, you can look at Lee or Singh-Ray, but I find that the cost saving (A typical Cokin P 1 stop G-ND runs <$40) is well worth having to take a little extra care.

As far as enhancing colours, yes, no, kind-of, sort-of... An ND/G-ND should cause absolutely NO colour shift of any kind, however they do give the affect of enhanced colour saturation by virtue of the fact that they reduce light transmission over part of the image circle. For instance: You're photographing a shoreline at sunset. The shore itself is somewhat dark, but the sun is causing blowing out the cloud detail in the sky. An appropriate amount of ND (In the form of G-NDs) will allow you to expose properly for both the shore and the sky by reducing by say two stops (for example) the amount of light that is allowed through the filtered part of the gel.

Regular NDs are most often used to achieve very low shutter speeds, for instance to get that soft, flowing water effect or when large apertures are needed in bright conditons. You can definitely achieve some reduction in light transmission (as well as a boost in saturation) by using a CPOL, but it's normally limited to 1 - 1 1/3 stops at most. -
This image (IIRC) used two full stops of ND to achieve a the 3 sec shutter-speed in bright sun.

As for types, there are two styles the gel (Cokin, Lee, Singh-Ray and no-name) and regular round filter. G-NDs are sub-divided further into gradual and hard transition, that is: The neutral portion of the filter is either visible as a fairly hard line usually around the middle of the filter, or a very gradual transition from top to bottom. For regular NDs, either round or gel are fine, but for graduated, I strongly recommend the gels as they allow you to place the transition point wherever you want.
As I mentioned Cokins which I feel are the best bang for the buck do suffer from some colour shifting (red), especially when the lens is pointing at or near the sun. In all but in all but the most extreme cases this can be overcome by shading the lens sufficiently. I use a Cokin or Lee holder (even if you buy the Cokin filters, I recommend spending the $$ on a Lee holder) and keep an 8x10 sheet of black craft foam in my bag which I use as a shade. Takes a couple of extra seconds, but as I said, IMO, worth the cost savings.