Polarizers, ND, and Grad ND Filters for the Landscape

By Rod Barbee

Filters are a big part of photography and every photographer needs a few. Three of the most useful filters for controlling contrast and shutter speed are polarizers, neutral density filters, and graduated neutral density filters. I have a variety of each in my camera bag and use them all regularly. 

For creative fun with long shutter speeds, use Neutral Density, or ND, filters. These are just like other filters that screw into the front of your lens, only they don’t alter the color of the scene (like warming filters do); they simply reduce the amount of light reaching the film or sensor. They usually come in one-stop increments from one to four or even five stops. However, they’re rarely designated in stop increments. Instead you’ll see something like ND 0.3, which means one stop. The following table will help you translate. 

ND 0.3                        1 stop
ND 0.6                        2 stops
ND 0.9                        3 stops
ND 1.2                        4 stops 

You may even see something like NDx4. That will be a two stop ND filter since two stops lets one quarter of the light through. It follows that NDx8 will be a three stop ND filter since it lets one eighth of the light through. That’s enough math for now.
All the major manufacturers including Tiffen, Singh-Ray, Hoya, B+W, Heliopan, and Sunpak make ND filters. 

Even with f/22, I was unable to achieve the slow shutter speed I wanted for this image. Adding a 2 stop ND filter did the trick.	By using an ND filter, I was able to fine tune the shutter and aperture to get exactly what I wanted.
1.3 second exposure	20 second exposure

With slower films disappearing from the market and some digital cameras with low end ISO speeds of 200, it can get difficult achieving slow shutter speeds of one half second or so. ND filters will allow longer shutter speeds or wider open apertures for more creative control. They are especially useful when you want to blur the motion of water, clouds, or flowers blowing in the wind. I find ND filters especially useful when photographing on the coast. With longer shutter speeds you can blur the water over several seconds, creating an ethereal, mist-like effect. 

One of the most intriguing filters available is Singh-Ray’s Vari-ND. To use it, you simply turn the filter to “dial in” the amount of neutral density you need, from two to eight stops. The viewfinder may get very dark so it’s best to set your composition before adding the filter. With a digital camera, you can experiment with different settings on the filter until you get just the effect you’re after.

ND filters are often overlooked by photographers, but as a creative tool, they’re some of the most useful filters you can own. 

Polarizers 

If you only can have one filter, it should be a polarizer. In my mind, it’s the most useful of all filters. Most people think of using polarizers to darken skies or to eliminate reflections, but what they’re really accomplishing is improving contrast.
Polarizers eliminate that annoying sheen and glare from vegetation, allowing the true colors to show. For this reason, I use polarizers in forests on overcast or rainy days.

Without polarizer	With polarizer
Without polarizer	With polarizer.

Polarizers can also cut out reflections from moisture in the atmosphere, reducing haze, and therefore darkening the sky. If I need to reduce the exposure in the sky, I’ll look to a polarizer first. Polarizers will also allow you to see through the surface of water and will eliminate glare from glass.
When you go to purchase a polarizer you’ll be faced with a choice between linear and circular polarizers. If you’re using an auto focus camera, or you plan to, get the circular polarizer as linear polarizers will interfere with the auto focus system. You may also want to consider getting a multi-coated polarizer. Multi-coatings on filters help to reduce flare, improving image quality.
Polarizers will cut between one and two stops of light, meaning you’ll need to use longer shutter speeds. This is sometimes an advantage if you need longer shutter speeds to blur the water in a stream. In fact, I’ve stacked a polarizer with a neutral density filter simply to get longer shutter speeds. 
But often, slow shutter speeds are not what you wanted, especially if it’s a little breezy along that stream and you really didn’t want those tree branches to be blurred as well. To help with this problem, Singh-Ray makes their LB (Lighter/Brighter) warming polarizer. This polarizer transmits more light than other polarizers, two thirds of a stop more light, with the same polarizing effects. This gives the photographer a shutter speed advantage as well as a brighter viewfinder. 

The easy way to tell if a polarizer is going to have any effect is to simply hold one in front of you and rotate it. Be sure the filter threads are facing you. If you like what you see when you turn the filter (often accompanied by an “oooh” sound), then use it. If it’s only a “ho-hum” that you hear, don’t bother attaching the filter.

If you use protective filters on your lenses be sure to take them off before attaching a polarizer. When you stack filters, you always run the risk of image degradation. And stacked filters can vignette the image (cut off the corners), especially with wide angle lenses. So unless you need to stack filters for a reason, such as adding warming to a polarizer or adding neutral density, avoid stacking.

High quality polarizers like those from B+W, Singh-Ray, and Heliopan can be expensive, but they are made to the highest standards. If you’re on a budget take a look at the Pro-Optic line manufactured by Adorama.

If you use ultra wide angle lenses, you may want to look into the thin mount polarizers made by Tiffen, Hoya, B+W, and Heliopan. These filters are generally more expensive than other polarizers but they do solve the problem of vignetting at the wider settings of wide angle zoom lenses.

For the landscape photographer, graduated neutral density filters are on the must have list, whether you’re shooting film or digital. Being half clear and half dark, you can use them to control contrast in landscape situations where the range of light is beyond the ability for film or sensor to record. They’re typically used when the foreground and background are in different light or are of widely different tonalities. Examples of this are sunrise and sunset when the background is lit and the foreground is in shade, and mountain scenes where snow capped mountains are significantly brighter than the foreground.

Using a grad filter in these situations, the camera controls the exposure for the foreground and the filter controls the exposure for the background, enabling you to capture the scene’s full range of light in one shot. 

Without filter	With 2-stop ND Grad filter

Graduated neutral density (GND) filters are available in different densities, usually one stop to four stops, and two different transitions: a gradual soft transition or an abrupt hard transition. They are also available as either screw-in or rectangular filters. The rectangular filters are by far the most useful since the screw-in versions force you to place the transition right in the middle of the frame. Rectangular filters come in different sizes. The most popular are 84mm wide, sized to fit the Cokin “P” style filter holder. Singh-Ray, Tiffen, Hitech and Lee make filters to fit these holders. The other size is 100mm by 150mm (4x6 inches) made by Singh-Ray, Lee and Tiffen. 

You have a couple of choices for placing the filter in front of the lens, using a filter holder and hand-holding the filter. The Cokin “P” size holders and adapters are widely available and inexpensive. I generally hand hold my filters in front of the lens. This allows me to work fast in quickly changing light and to more easily place the filter. Plus I find it more convenient than attaching adapters and holders.

But hand holding takes a little practice since the filter needs to be flat against the lens and it also needs to cover the entire front of the lens. With practice, this becomes easy. Unfortunately, the P-sized filters (84mm wide) just barely cover lenses with large diameter front elements. This gets even more problematic with today’s ultra wide zoom lenses with 77mm thread sizes. With the depth of field possible using these lenses, it becomes all too easy to include a finger or an edge of a filter in the final image. Believe me, I know.

To address this problem several manufacturers including Singh-Ray, Lee, and Tiffen make filters that measure 4x6 inches, available in all the usual densities and transitions. These over-sized filters are much easier to hand hold. Plus, being so large, they give the photographer more creative options such as deliberately moving the filter up and down during an exposure to further “feather” the transition area. Holders made by Lee and Cokin (Cokin Pro Z) are also available for these filters. 

GND filters are more complicated to use than polarizers or ND filters. First, you need to determine which strength of filter to use. The trick is to use these filters so that no one knows you’ve used one. If the filter is too strong, you’ll end up with a background that looks unnaturally dark, and if the filter is too weak, the background will look overexposed or your foreground may look too dark. This is why you need more than one graduated ND filter. I carry 1-stop, 2-stop, and 3-stop filters in my bag and I use them all.  

These days, many digital photographers forgo the Graduated ND filters and opt for making two or more exposures of a scene and then blending them in Photoshop. This works great, but if spending extra time in front of the computer doesn’t trip your shutter, graduated ND filters are the way to go. 

In this digital age, photographers are carrying fewer and fewer filters. But these three filters: polarizers, neutral density, and graduated neutral density are still useful and necessary filters to have in the camera bag.