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.
|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.
|With Neutral Density Filter - ND 2|
|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 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.
|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?