Discussion on the use of Neutral Density filters in Landscape
Photography.
Firstly, what is a Standard Neutral Density filter?
In the days before Photoshop or Lightroom, photographers used a lot of different
filters on their lenses to create effects or enhance colour and contrast. Coloured and
soft focus filters are now no longer needed because their effects can be duplicated
easily in post-processing. Warming/cooling filters for different types of light are also
no longer useful because most digital cameras have a white balance setting that
makes them completely obsolete.
However, some filters cannot be easily replaced with a simple Photoshop command,
and one of the most practical is the neutral density filter (ND).
A neutral density (ND) filter is a piece of tinted glass or resin which attaches to your
lens and reduces the amount of light that passes through the lens of your DSLR,
allowing you to use a slower shutter speed or larger aperture to obtain the same
exposure you would have achieved without the filter. The word Neutral is meant to
mean neutral in colour and can also be known as Grey, indicating that there is no
colour added to the final image. ND filters work by blocking a precise and uniform
amount of incoming light in any given scene. Because an ND filter blocks an equal
amount of light across the whole visible spectrum, it doesn’t impact other elements
such as contrast or sharpness.
ND filters look tinted (like a pair of sunglasses), but the camera “sees” through them
in pretty much the same way your eyes see through a pair of sunglasses, so the tint
doesn’t show up in the final image.
When would we use a ND filter?
Situations where we might want to use an ND filter could be; strong daytime light
when we want to achieve a longer exposure; for example to slow the movement of
water in a stream /waterfall /ocean waves; to give the effect of movement in clouds
or to dampen the strong middle of the day light in a rainforest.
Why is this useful? Because it gives you more control over your final image.
(Tip: you can “stack” several ND filters to increase your light reduction, which may
eliminate the need for one of the more expensive variable ND filters).ND filters come
in different strengths from 1 stop of light to right up to 20 stops of light.
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ND filter strengths are expressed as below;
Note; Another option is to buy a variable circular ND filter which has a range from 1
stop up to 10 stops of light.
ND filters come in 2 shapes; either Circular or square/rectangular.
The Circular ND filters screw directly onto your lens and provide a reduction in the
amount of light hitting your sensor so that the whole scene will be darker by
whatever amount the filter is rated. The rectangular ND Filters fit into a bracket which
in turn is fitted to your lens by means of an adapter ring.
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Graduated Neutral Density Filters;
In addition to the standard ND filter there is the Landscape photographer’s best
friend, the Graduated Neutral Density Filter. As the light above the horizon is nearly
always brighter than the light below the horizon the photographer wants to try to
close the gap between those extremes of light to give a more even range of light and
contrast across the scene.
This Filter comes as either a Hard or Soft Graduated ND Filter. These filters are
always rectangular and have a gradual change from clear, (no darkening) to
maximum darkening and are fitted to a bracket to allow the photographer to place
the change in darkness where the horizon is. The Soft Graduated neutral Density
Filter (SGND) is definitely the most used filter for Landscape photography.
A Graduated ND filter (GND) is good for brightly lit scenes where you want to
maintain detail in the brightest and darkest regions. When photographing a scene
with a bright sky, for example, you can position the graduated ND filter so that the
darkest portion is above the horizon, and the lighter part is below the horizon. This
will help maintain colour in the sky and/or bring out detail and definition in the clouds
while also maintaining detail below the horizon.
Examples of Square or Rectangular ND Filter set ups
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Problems to be aware of when using ND filters;
Colour Cast can result – often a Magenta colour.
Vignetting on Wide angle Lenses especially with Circular Polarisers
Common brand names of ND Filters;
LEE
COKIN
HOYA
CAMDIOX
TIFFEN
Further reading and Information;
http://www.martinbaileyphotography.com/2013/10/14/all-about-neutral-density-filterspodcast-391/
https://en.wikipedia.org/wiki/Neutral_density_filter
http://www.digitalcameraworld.com/2012/07/05/how-and-when-to-use-nd-filters-andwhat-the-numbers-mean/
http://www.imagen-estilo.com/Articles/Filters/nd-filters-explained.html
https://www.youtube.com/watch?v=Z0rubRtnavY
https://www.youtube.com/watch?v=Fcxzx8U69xA
https://photographylife.com/lens-filters-explained
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Overview of types of lens filters
Here is a list of typical lens filters you can purchase today, along with descriptions of their purposes:
Lens Filter
UV/Clear/Haze Filter
Photography Type
Purpose
Any
Protects the front element of a lens from dust, dirt, moisture and potential scratches.
High quality UV filters can be permanently mounted on lenses with a minimum impact
on image quality.
Polarizing Filter
Any
Filters out polarized light, dramatically reducing reflections, enhancing colors and
increasing contrast. Can be used for any type of photography. Polarizing filters are
typically circular, allowing for easy control of the effect of polarization.
Neutral Density (ND) Filter
Landscape, Flash
Reduces the amount of light entering the lens, thus decreasing camera shutter speed.
Photography
Useful for situations where motion blur needs to be created (rivers, waterfalls, moving
people) or large apertures must be used with flash to avoid overexposure.
Hard-Edge Graduated
Landscape Photography
Hard-edge GND filters are primarily used in high contrast situations, where the sky is
Neutral Density (GND)
much brighter than the foreground and the horizon is flat. These filters are always
Filter
rectangular (giving the ability to move them in all directions) and are typically used
with filter holders.
Soft-Edge Graduated
Landscape Photography
Neutral Density (GND)
Soft-edge GND filters are also used in high contrast situations, but where the horizon
is not necessarily flat. The soft edge allows for smoother transitions, making the use
Filter
of a filter less evident. Soft-edge GND filters are also rectangular and are normally
used with filter holders.
Reverse Graduated
Landscape Photography
The reverse GND is a specialized filter used by landscape photographers when
Neutral Density (GND)
shooting against the sun while it is setting close to the horizon. While a regular GND
Filter
filter gradually transitions from dark to clear towards the center, a reverse GND filter
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Lens Filter
Photography Type
Purpose
transitions from dark to less dark from the center to the edge.
Color/Warming/Cooling
Any
Filter
Corrects colors, resulting in a change in camera white balance. Some color filters can
subtract colors, blocking one type of color and allowing other colors through. These
types of filters were popular for film. They are rarely used in digital photography, since
their effects can be easily applied in post-processing.
Close-Up Filter
Macro Photography
Also known as “diopter”, a close-up filter allows a lens to focus closer on subjects.
These filters are only used for macro photography.
Special Effects Filter
Any
There are a few different types of special effects filters. Star filters make bright objects
look star-like; softening/diffusion filters create a “dreamy” look used for portraits,
multivision filters create multiple copies of a subject; infrared filters block infrared and
pass visible light; bokeh filters have a certain shape cut in the middle of the filter that
makes bokeh highlights have the same shape, etc.
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