Monday, May 11, 2020

Circular Polarizers Versus Graduated Neutral Density Filters for Landscape Photography

Whether you’re a professional or hobby photographer, odds are you’ve come across a beautiful, scenic landscape, that you absolutely had to photograph. Unless you’re an experienced landscape photographer, there’s a good chance the color in that photo wasn’t as saturated, or balanced as you were expecting. That’s because there’s generally a wide disparity in the dynamic range between the foreground and background of landscapes, as well as between the upper (sky) and lower (earth) halves of the frame. Thanks to a couple of lens filters, this hurdle can easily be overcome without having to spend hours of post-processing in Photoshop.
Drop-in and screw-in filters

What are lens filters?

Lens filters are lightweight pieces of glass that screw onto the front of most camera lenses (or drop-in using a holder system) in order to offer additional protection of your lens while also improving image quality. There are a variety of filter sizes that must match up to the size of the thread on your camera lens, so it is very important to make sure you get the correct size for the lens you plan to use it on (tip look on the back of your lens cap).
In addition to varying sizes, lens filters can also serve several different purposes. Most basic lens filters are ultra-violet (UV) reducing filters (also known as haze filters) that come with an anti-reflective coating to cut through the effects of atmospheric haze, thereby improving overall image quality. Besides UV/haze filters, there are two others that are particularly useful for landscape and outdoor photography – polarizers and graduated neutral density filters.

From left to right: A clear UV filter, a polarizing filter, and a Graduated Neutral Density filter.

What is a polarizing filter?

The next filter we’ll discuss is the polarizing (usually circular) filter, which attaches to the front of a lens and can be spun around to produce varying degrees of saturation throughout an image. This quality of the polarizing filter is important to pay attention to, because it’s easy to produce uneven shades of saturation if the polarizer is even slightly off, such as in the example below.

Circular polarizer versus ND grad filter

Landscape photo with uneven polarization. Notice how the sky is very uneven in color.

Sony a6300 camera with bare kit lens – no filter applied. UV and Polarizing filters on the table.

Polarizing filters do two things: first, they help reduce glare or reflections cast by non-metallic reflective surfaces such as glass or water. Second, they saturates colors and enhances image clarity by reducing the overall exposure of an image. The benefits of the polarizing filters are best seen when you are shooting at a 90-degree angle to the sun.
Take a look at the landscape photo below that was taken with no filter, the colors are muted and not very exciting. However, once the polarizing filter is added, you can see a huge boost in overall color saturation. It’s a pretty dramatic difference without even post-processing the photo.

Landscape photo with no filter.

Landscape photo with a circular polarizing filter. Notice how overall the colors are intensified.

What is a neutral density filter?

Another effective filter for landscape photography is a neutral density (ND) filter, which reduces the overall exposure of an image. ND filters are uniformly dark in color and they come in different strengths depending on density.
The best use of ND filters is in situations where you wish to use a long exposure or wide aperture to capture an image, without risking overexposure. Some example scenarios when a ND filter would be effective include:

Producing a smooth, blurred movement of water in a waterfall, lake, or the sea.
Blurring moving subjects to convey movement or motion (such as panning).
Reducing diffraction by using a large aperture.
Shooting with a shallow depth of field in bright lighting.

What is a graduated neutral density filter?

ND filters also come in a graduated form, also known as a split ND filter. The top half of the filter appears dark, while the bottom half is clear. Similar to the circular polarizer, the graduated ND filter can also be spun around to produce varying degrees of saturation, so it’s important to be careful when using it to avoid unevenly saturating your image.
The best scenarios for a graduated ND filter to shine are when you wish to reduce light, or darken just part of your image. Think landscape photos where the earth is balanced, but the sky is blown out. This would be an ideal time to use a graduated ND filter to darken the sky.

The above landscape photo with a soft edge ND grad filter. Notice how the sky is darker and more

saturated, while the water hasn’t changed.

There are two types of ND grad filters: hard edge, and soft edge. You’ll want to use a hard edge filter when the light and dark sections are very clearly separated, while a soft edge filter is best used when the light and dark sections are not distinctly separated.