Filters - Traditional vs Digital
Since the advent of digital
photography the use of many effects filters has been largely made redundant.
This is because almost all of the effects achieved by traditional filters
can be recreated through image editing software which can apply unlimited types
of filters onto the same image.
However, there are some filters which
cannot be easily recreated digitally and these continue to be used on
interchange lens cameras (DSLR & mirrorless) today. Below we have
listed these filters along with a description on when you would use them in
your photography.
Circular Polarising Filters
The circular polariser is a very
useful filter. It can be effective in both colour and black + white
photography; particularly with landscapes, seascapes and architecture type shots. Its
trick is reducing reflections off all non-metallic surfaces, including the
atmosphere. Landscape photographers use it for making a blue sky appear a
deeper shade of blue. Other uses include making foliage look greener by
cutting back the glare coming off the leaves and also removing reflections off
water so you can see into the depths. This allows you to see fish in a
pond that may have been lost due to reflections from the water’s surface.
This filter will also allow you to
see more clearly through glass windows by cutting out the reflections.
Some windows that have a polarising film on them, for example some
aircraft windows, will cause you to see a crazy rainbow across the frame, this
is called 'cross polarisation’. It happens when you have two polarising filters
in front of your lens. The effect that this filter will have will vary according to
the angle that the light is bouncing off the subject in relation to your
position.
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| Without Filter |
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| With Circular Polariser Filter |
Neutral Density Filters
A neutral density (ND) filter
works by reducing the amount of light that enters your camera by a neutral (no
colour cast) filter that absorbs a varying amount of light depending on how
dark the filter is. These come in several shades such as ND2 (1 stop less
light), ND4 (2 stops less), ND8 (3 stops less) and even ND400 (a whopping 9
stops). You can also get variable ND filters that cover the whole range
mentioned above in one filter.
Landscape photographers love this
filter. This one comes in handy when you need to extend either the length
of your shutter speed, for example when you want waves in the foreground of a
seascape to look all smooth and silky, or want to get a very shallow depth of
field by using a large aperture in ultra-bright conditions.
The different darkness ratings
are used to fine tune the effect and the filters can even be 'stacked' together
to fine tune the effect. Videographers use this filter to adjust the
exposure to get the correct shutter speed resulting in smoother looking videos.
ND filters require a tripod and
remote release to be used especially if you are required to complete very long exposure
times. A tripod and remote release will reduce the chance of camera shake and
movement to achieve the sharpest possible image.
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| Without Filter |
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| With Neutral Density Filter - ND 2 |
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| With Neutral Density Filter - ND 8 |
Neutral Density Graduated Filters
Neutral density graduated filters
(ND grads) are used to reduce the brightness over a section of your frame to
even out the exposure values across the photograph. If you have a very
large difference between the brightest part of the frame and the darkest part
you will end up with either blown out highlights or blocked out shadows. This
leads to no information in the highlighted area so you end up with a white haze
or no information in the shadows, just a black block.
For example, if we are taking a
photo of a sunset and we want to have detail in the foreground so we can see
the trees etc. and we also want detail in the sky so we can see all those
clouds and colours. We compose the photo so that the sky takes up the top
two thirds of the frame and the ground takes up the bottom third. We take
a reading from the camera which exposes the sky perfectly but the foreground is
silhouetted and we can see no details in it. We adjust the exposure to
gain detail in the foreground but when we take another photo we find the sky
has blown out and there is no longer any details in the clouds.
Even shooting in RAW and
adjusting later does not always get detail back into these areas, so what is
the solution? The ND grad. If we put an ND grad on the lens and adjust it
so that the dark part covers the sky and the light part covers the ground then
take another photo then we can see that the dark part of the filter has reduced
the brightness in the sky and the clear part has not changed the brightness
level in the foreground. The filter has compressed the contrast in the
image, i.e. the difference between the brightest part (the sky) and the darkest
part (the foreground) is now able to be captured in one single image and still
retain detail in both the sky and the foreground.
Infrared Filters
Infrared filters are a
special effect filter that blocks out most of the visible spectrum of light but
will let part of the infrared spectrum through.
These filters can be
very handy to carry around with you in your kit bag. You may not use them
all the time but when you need them they are indispensable. If you have a
few different lens filter sizes then maybe consider something like the Cokin
filter system. This way you can buy one filter that can fit on several
lenses simply by purchasing an adapter for each lens, rather than a filter for
every lens, it's much cheaper and just as good.
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| Without Filter |
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| With an Infrared Filter |
Consider your Next Filter Purchase
The four filter types
above offer something that can't be easily achieved in Photoshop. They
can make it possible to do things in camera quicker and easier than digitally
manipulating the image later. There are many brands of filters that set out to help you achieve the same if not similar outcomes including Hoya, Manfrotto, Cokin, Kenko and Inca.
Are there any other filters that
you can think of that can't be recreated digitally?
