Neutral Density Filters

[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.

[Marko]

Thanks for this Good info T.I and others!- I think this might make a good podcast topic!

I should say that now that most of us are shooting digitally, when the scene is static, you can simply take a second exposure on a tripod of course, just for the sky and blend it in photoshop.

[EJC]

The P series from Cokin has a wide angle holder. It'll only hold 1 filter at a time, but what I've been told it works without vignetting on 10mm (crop camera). Not sure what it does on full frame though...

I have a Cokin P holder with 3 slots. So far I only have a single GND4 to put in it. I hope to get out this weekend to try it.

Oops. Fingers started before my brain Fourtytwo. Mine is a standard holder not a wide angle.

[Greg_Nuspel]

I had a set of ND filters and used them lots for waterfalls and ocean waves, they now reside at the bottom of Elbow Falls

I saw some excellent info on graduated filters comparing them and such, most complain about the not so neutral colour shift of the Cokin filters, but at the price of the others I'd have to sell off my last son; he's 17 years old 6' 5" 210 lbs. really good cook, looking for reasonable offers

[Bambi]

I had a set of ND filters and used them lots for waterfalls and ocean waves, they now reside at the bottom of Elbow Falls

I saw some excellent info on graduated filters comparing them and such, most complain about the not so neutral colour shift of the Cokin filters, but at the price of the others I'd have to sell off my last son; he's 17 years old 6' 5" 210 lbs. really good cook, looking for reasonable offers

sorry I already have one of those.

[JAS_Photo]

Here is a link to Jim Patterson's blog where he explains how he uses filters and more

Jim Patterson Photography

[zenon5940]

Thank you for this good link Jas. Very interesting description on how to use ND filters and calculate the right exposure settings.

[Marko]

Just an FYI - I've mentioned this elsewhere as well but this will be our next podcast . I'll do some general talk on the topic as well as interview Darwin Wiggett and get the benefit of his amazing experience.

One key point that has been touched on is ND filter versus Polarizer. A polarizer is bluish so bluish colour shifts are normal. ND is greyish. It's not supposed to create any colour shift at all. Polarizer is a leave it on your lens for outdoor shooting kind of filter. ND's are more specialized, often used to reduce overall brightness in order to use a slower shutter speed for 'blurring' effects.

[JAS_Photo]

That will be cool, Marko! I just got a polarizing filter (CPol) for my good lens. Since the lens was quite expensive, I wanted to get a good one and after driving the salesperson equally crazy as I have everyone here on this topic, I chose one of Singh Rays 'light and bright' warming polarizers. (To start! Ha!)

Darwin Wigget is great! I am excited to hear the new podcast.

[squirl033]

i have both a grad ND and an ND4 filter, and, of course, a polarizer. i rarely use the ND4, except when i'm shooting flowing water on a bright day, but it's nice to have for that. the grad ND gets more use, typically to darken an overly bright sky so as to even up the exposure with a darker foreground (or, in the case of snowy terrain, vice versa...). my polarizer doesn't stay on all the time, by any stretch... usually only put it on when i want to cut glare or enhance contrast in the clouds. it gets a fair bit of use in summer and fall, but in winter, it's usually so dark and gloomy here there's never a need for any kind of filter to get slow shutter speeds, and there's nothing for a polarizer to work on anyway... :( i find myself leaving the polarizer in the bag at high elevations, though... above about 4,000 feet, it makes the sky too dark, almost indigo.