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You don’t need physical filter for landscape photography anymore! Read here before you waste money on filters.
Unless you want to invest as little computer time as possible in your photographs. Filters are expensive and should not be the first purchase in landscape photography. Most of the functions of physical filters in landscape photography can be replaced by proper image processing. It is even possible to achieve much more photorealistic results than by using filters for landscape photography.
In this article we want to take a realistic look at the use of filters.
No one who owns a camera that can photograph all three colours: red, green and blue, needs colour filters. Colour filters are only useful for taking photos with black-and-white films in old, analogue cameras. In photo shops these filters are sometimes sold to beginners, and since they seem to be much cheaper than the camera or the lens, people like to take them along.
Quite simply, a camera that shoots in black and white cannot store any colour information, be it on film or with a digital sensor. This camera only records the brightness information of all colours of the optical spectrum (red to blue). With a colour filter, only a certain colour can pass through a black and white camera.
Through the blue filter, only the blue light reaches the image sensor. This means that, for example, in a green meadow, the green of the grass no longer reaches the film. The meadow becomes very dark. The blue sky, on the other hand, remains untouched. The contrast between the meadow and the sky is increased in the black and white photo.
However, if you have a camera that photographs in colour, this camera ALWAYS takes red-green-blue as colours. Yes, even if you have set the camera to take black and white photos.
The RAW file is in colour. If you now want to use only the blue light to have a high-contrast black and white photo, you can simply fade out the red and green channel and have the same effect as with a blue filter on a black and white camera.
With colour filters on a colour camera you get extremely strange distortions of the colours that will only ever work to your disadvantage.
This filter is also very often sold in photo shops. This filter also serves no purpose on a modern, digital colour camera. Old colour films and black and white films had a sensitivity to UV light. To prevent this, a UV filter was placed in front of the lens.
Modern image sensors also have a sensitivity to UV radiation. For this reason, there is a UV filter already installed directly in front of the photodiodes of the image sensor. There is therefore no reason to use another filter in front of the camera. Exactly the same applies to the other end of the optical spectrum: There is also an IR cut filter in front of the image sensor. It is therefore also not necessary to use an IR filter.
This filter serves no purpose except to protect the lens. Those filters for landscape photography are only useful in a few situations. For example, if you want to protect your lens from the sand in a strong wind in the desert. Otherwise, any filter glass in front of the lens will result in a deterioration of the image quality.
Even a clear glass protective filter can reduce the resolution of the lens by 2-3%. Cheap products that can be bought for a few euros have much worse properties and can even reduce the resolution by 5%! This is where the typical “weakest link in the chain” comes into play. If you put a 5€ filter in front of a 1000€ lens, you have to realise that all light that passes through the lens has to pass through the filter first!
Otherwise, every filter in front of the lens creates so-called lens flares in backlight situations. Lens flares are light reflections that occur on any optically active surface when it is directly in the angle of view. In the case of filters for landscape photography, this means: The sun. The sun is reflected in the filter glass, then reflected in the front lens of the lens, and so on. At the end of this chain, unsightly coloured spots appear in the photo. These are called lens flares.
For this reason, your “always on” glass filter, UV filter or IR filter may cost you 5% of the image quality and ruin your photo in backlit situations! Filters for landscape photography should always be carefully weighed and only put on the lens when really needed.
By the way: if you drop your lens or camera, the thin glass of a filter unfortunately rarely helps to prevent the stone from drilling through to the front lens.
The polarising filter is again one of the filters that you are sold in the photo shop with the words “it makes the contrast in the photo better”. This is no lie, but those filters for landscape photography only do this in very specific situations. And only in these situations does the filter have a place on the lens. As you can see from the dark colouring, this filter absorbs a large amount of light.
This is not good, because it increases your need for exposure time or a higher ISO level. This results in motion blur or higher image noise. There is also a loss of resolution, of course.
You should note that this filter is rotatable. The polarisation filter filters out a certain polarisation direction of the light. It absorbs light. What is polarised light? There is no light without polarisation. Light is a transverse wave and therefore has a plane in which it oscillates.
In a laser, for example, the light oscillates in only one direction, it is polarised. Unpolarised light oscillates in all directions at the same time. This is true for almost all light sources. Polarised light is an exception, unpolarised light the rule. When using the polarising filter as a filter for landscape photography, only one light source comes into question and that is the sun. Either directly or, on a cloudy day, indirectly. The light of the sun is completely unpolarised.
In a laser, for example, the light oscillates in only one direction, it is polarised. Unpolarised light oscillates in all directions at the same time. This is true for almost all light sources. Polarised light is an exception, unpolarised light the rule. When using the polarising filter as a filter for landscape photography, only one light source comes into question and that is the sun. Either directly or, on a cloudy day, indirectly. The light of the sun is completely unpolarised.
If you use a polarising filter, it has no effect on sunlight, except that it costs a little light, because the polarising filter removes one oscillation plane of the light. This is not noticeable because all the other spatial directions are still there. There are only two phenomena in nature that produce polarised light: a reflection and Rayleigh scattering.
Rayleigh scattering occurs in the sky. The blue light you see in the sky is polarised light. The shorter the wavelength, the more likely the light is to be scattered by dust and haze in our atmosphere. So with the polarising filter you can filter out the blue light in the sky. To do this, turn the polarising filter until the sky becomes darker. Then the filter and the polarisation direction of the sky are parallel.
Reflections, water reflections and whiteness can be found everywhere in nature, for example on water. You can find whiteness on leaves of trees and bushes. You can then use the filter to remove the shine in the landscape and create somewhat richer colours. The effect is minimal. The polarising filter is therefore only useful in a few cases.
This filter is often used to smooth water or cloud movements. At the sea or for slowly moving clouds, the filter is useful. But not with waterfalls! With waterfalls, an exposure time of 1s or 30s no longer makes a noticeable difference. Since the water is blurred anyway by the long exposure time, you can also photograph the waterfall with a closed aperture of f/22 or f/32 to force an exposure time of 1s.
In addition, make a second exposure at an ideal aperture of f/5.6 so that both photos are equally brightly exposed. On the PC, you can overlay both exposures in the image processing and get the same effect as with a grey filter.
Most waterfalls are also located in a forest or gorge. The most beautiful light moods also occur when the sun is just above the horizon, or during the blue hour. If you take photos at this time, you can easily achieve longer exposure times without a filter. The same applies to the sea. If you want to photograph the sunrise and have the water very soft, then come some time before sunrise and photograph the water when it is still darker.
In summary: Instead of using grey filters in landscape photography, you can simply choose a darker light situation and combine several exposures.
There is no reason to use graduated grey filters. The effect created by the filters is more problematic than the use of exposure bracketing and HDR photography. The aim of a gradient filter is to compensate for the typical backlight situation at sunset or sunrise when used as a filter for landscape photography. With our eyes, we see both a bright foreground and a sky that is not too bright in a backlit situation.
For the camera, however, either the sky is too bright or the foreground is too dark. This is due to the dynamic range. The dynamic range of the eye is about three times as high as that of the best digital cameras currently available. This means that our eyes can capture situations that have three times the contrast range as our camera.
The idea of the grey gradient filter is to compensate for this problem in a typical light situation in landscape photography, when the sky with the sun is simply too bright. This works well when it is a flat landscape. However, as soon as the horizon is not a straight line, or an object extends far up into the sky from the horizon, this filter reaches its limits and becomes useless.
The grey gradient filter darkens a tree or mountain reaching into the sky as well as the surrounding sky. This means that the lower part of the photo is suitably exposed, but the tree or mountain is black and you have gained nothing for your photo. If, on the other hand, you make a series of exposures and combine them on your PC to create an HDR photo, the mountain will have the same brightness as the rest of the foreground. Despite the image processing, the photo will look more natural than the photo taken with the physical grey gradient filter.
