How to use camera filters
Read our Ultimate Guide to Landscape Photography Filters. In this article you’ll find all camera lens filters explained in great details, including all types and how to use them.
Table of Contents
UV and Skylight Filters
Skylight and UV filters are screw-in filters, which attach directly to the front of the lens. They are often used to protect the front of the lens from scratches, fingerprints, dust, sand etc and can offer some protection if the lens is dropped– it’s more cost effective to replace a damaged filter than it is the lens!
Both filter ultraviolet light, helping to reducing the haziness sometimes seen in landscapes on summer days and in doing so, give clearer, crisper results. They are particularly useful when shooting snowy scenes as snow reflects UV light, giving it a blue cast.
Unlike a UV filter, a skylight filter has a slight pink cast to it, which was originally designed to reduce the very slight blue cast sometimes present when shooting landscapes with a blue sky on colour film. On a digital camera with automatic white balance, the effect of this pink tinge is removed; so the two filters are essentially are doing the same job. Both filters are clear and do not reduce the amount of light entering the lens.
It is best to pay a little more for a good UV filter; multi coated ones are designed to help maximise light transmission.
What to watch:
If using a wide-angle lens, remember to remove the UV or skylight filter when using other filters such as polarisers or graduated filters. Failure to do this will lead to an increased chance of vignetting. Not only this, but having too many layers of glass in front of the lens can lead to possible flare and degrade image quality.
The Polarising Filter
A polarising filter is one of the most useful filters for the landscape photographer and unlike other colour correcting filters, it cannot be digitally simulated. It is a very versatile filter and can have a significant impact on the end result of your images.
What is a polariser used for?
A polariser can be used in a number of ways. Its main purpose is to reduce reflections and glare, and by doing so, saturating colours. It is often used on water, but also on foliage, and other surfaces, the classic example being to enhance blue skies, making them look a deeper and richer blue and thereby having more impact on the viewer.
A polariser can have a dramatic effect on an image, giving in more vibrancy. When used on water it can also be very effective, not only by reducing surface reflection and glare, which can be distracting, but in doing so, enabling the photographer to see through the water, therefore enhancing any rocks or colours underneath the surface.
A polariser can also be used to reduce the amount of light entering the lens, and, by doing so, it will lengthen exposure times (this is particularly useful if you don’t have an ND filter to hand).
How does a polariser work?
A polariser works by blocking polarised light rays that are reflected towards your lens at certain angles. In doing this it removes glare, which in turn increases colour saturation and contrast and gives greater detail. Polaroid sunglasses work in exactly the same way, getting rid of glare and making colours look richer.
Types of polarising filter.
There are two types of polarising filter; linear and circular. These terms do not refer to the shape of the filter, but the way in which the filter modifies the light waves that pass through it. The type of filter required depends on the camera. If you use an autofocus SLR (digital or 35mm) you will need a Circular Polariser. A Linear Polariser will interfere with the complex metering and AF systems of modern cameras. If you use a manual focus camera, whether 35mm or medium format, you can use either a Circular or a Linear Polariser.
Polarisers can come in screw in form with a rotating front ring that screws directly onto the front of the lens and is rotated from there, or they can slide into a filter holder and be rotated within. You can adjust the filter while looking through the viewfinder varying the amount of polarisation until the reflections are reduced.
To get an idea of where in the frame polarisation will be the most effective, you can use your index finger to point at the sun, and then hold your thumb out, rotating your wrist as needed whilst keeping your finger pointed at the sun. Wherever your thumb is pointing is the part of the frame where the polarising filter will have the maximum effect.
Tips on using polarisers:
- When used in addition to a UV or skylight filter, and particularly on wide-angle lenses, there is a chance of vignetting. Remove the UV/Skylight filter to get around this.
- When used on skies, be careful on a wide angle lens – anything over 28mm on a full frame camera can lead to uneven polarisation and areas of dark and light blue which look false.
- When used in addition to a UV or skylight filter, and particularly on wide-angle lenses, there is a chance of vignetting. Remove the UV/Skylight filter to get around this.
- When used on skies, be careful on a wide angle lens – anything over 28mm on a full frame camera can lead to uneven polarisation and areas of dark and light blue which look false.
- Exposure – a polariser will reduce the amount of light entering the lens thereby leading to a different exposure calculation; the amount of which is roughly two stops. If working in aperture priority do make sure to keep an eye on your shutter speed. You may have to compensate with a faster shutter speed or possibly a tripod.
- Bear in mind that time of the day plays a big part in the amount of polarisation you can get from a polarising filter. You can obtain maximum polarisation when the sun is at about 37 degrees from the horizon, so if the sun is directly overhead or very close to the horizon, the effect of the polariser will vary and in some cases you might not even see any polarisation effect at all.
- Be careful of uneven polarisation. For maximum effect a polariser works best at a 90-degree angle to the sun and has minimum effect at an angle of 180 degrees. When shooting at 90 degrees you may find the colour of the sky will be irregular and noticeably darker in one area, which will look odd. Wide -angle lenses are the worst culprits for this as they capture such a large area of sky. Experiment with having the angle at approximately 45 degrees to the sun, rather than the full 90 degrees, for a more natural-looking result or select a longer focal length.
- If you have some fluffy white clouds, against a blue sky, a polariser will really help enhance them and make the sky much more dramatic.
- When shooting to prevent reflections, it’s best if you are at an angle of around 35 degrees to the reflective surface.
- A polariser will add contrast. Make sure you check your histogram to ensure that all detail in both highlights and shadows is being captured. Shadows will appear deeper so be careful when including large areas of shadow in your image that they don’t just turn into big black holes!
The Neutral Density Graduated Filter
What is it used for?
Graduated filters help cameras record scenes more like we see them; with a broad tonal range, by helping us to control highlight and shadow detail. In landscape photography they are used to balance exposure across the scene, most often the brightness of the sky with the land. When correctly used they give a more natural looking result than HDR processing. Also, unlike applying a digital graduated filter effect, that simply places a uniform darkening tone over the areas without any detail, ND grads enable the camera to record the highlight detail and bring out the subtle tonal variations.
How does it work?
The camera and human eye do not see the same way. The human eye is incredibly sophisticated; our vision has a ‘dynamic range’ (or subject brightness range) of around 24 stops, allowing us to see detail in areas of both shadow and highlight, even on a bright day. In contrast, a cameras dynamic range is far more limited. The quality and size of the sensor can determine the range but it’s typically around 8-12 stops which is very often far narrower than the dynamic range of the scene being photographed, thereby creating exposure issues. In this instance, either the darker areas of the scene will be underexposed and appear completely black, or the brighter parts will be over exposed, indicated by the flashing areas in the image on the LCD screen. In both cases detail is lost. A Neutral Density Graduated filter allows the photographer to capture a scene that would be virtually impossible to photograph otherwise. By positioning the darker part of the filter so it covers the brightest section of the scene the photographer can set an exposure that retains all the detail.
Types of ND graduated filter
ND grads (for short)are pieces of glass or photographic resin that are clear in one half, and darker in the other, with either an abrupt or a gradual shift in the middle, depending on whether you opt for a hard or soft version. Resin is lighter and more affordable than glass and also more likely to survive dropping. On the downside they are more prone to scratches. In either case they need to be stored carefully.
These filters come in two types; screw-on, which screw onto the front of the lens and square or rectangular ones that slip into a filter holder attached to the front of your lens. This is the more versatile option as it enables the filter to be moved up and down as well as rotated. They’re also made in a range of sizes, to accommodate small, medium and large format cameras. There are several filter systems on the market. I can personally recommend Kase Filters for their quality and durability. Find out more here about why I use Kase filters.
What strength?
ND grad filters are available in different strengths, allowing you to choose the one most appropriate, depending on the level of contrast between the brightness of the sky and land. Most manufacturers produce a range of filters capable of cutting out one, two or three stops of light, but some, such as Lee Filters, produce grads with intermediate strengths for greater control of exposure. It can get also confusing as different manufacturers give them different names, such as ND4 or 0.6 ND – both indicate a filter of the same density, which will reduce the exposure by two stops across the area which it covers.
Hard or soft?
With both types, the darkening of the filter begins in the middle. A soft filter gradually gets darker as you move from the middle towards the other end of the filter, whereas the hard type has a defined line, quickly changing from clear to dark.
Whether you use a soft or a hard grad will depend mainly on the subject matter of your image.
As a general rule, a hard grad would be used for images containing a clearly defined horizon, or any hard transition between the sky and the foreground whereas a soft grad works best where there is no definite transition between sky and foreground. Soft grads, having a more subtle transition, are less obvious to the eye and can be trickier to position correctly because it is harder to see their effect in the viewfinder.
In addition, only a small part of the filter at the top is fully dense before it then fades out towards the centre. As the brightest part of the sky is usually just above the horizon, it becomes necessary to push the filter down further so it overlaps the ground. Whilst hard grads can be aligned with more precision, they create a more defined line between light and dark in an image. Therefore they need to be used with care as they can be spotted easily on subjects that cross from the darker part of the image into the brighter area; for example a tree or a building, resulting in an unnatural look.
Using an ND Grad
The key to using an ND Grad is to select the appropriate one (strength and type) and then position it correctly so that no one can tell you’ve used one. It should not be obvious.
Positioning the filter:
Method one
1) Set the camera to manual exposure mode and, without the filter in place, take an average centre weighted or evaluative meter reading for the foreground.
2) In the same way, take a reading for the sky and note the difference in the two readings.
3) Dial the foreground reading into your camera
4) Select the correct filter to control this difference in exposure to within one stop (the sky is usually naturally brighter than the land) eg: if the sky is 3 stops brighter, use a 2 stop filter.
5) Slide the filter into position. Take your time to slide it up and down until the transition line falls exactly where it is needed – on the point that the light and dark areas of the scene meet. With a landscape this is usually at the horizon. The darkening effect should be visible through the viewfinder or on the LCD screen. Slide the filter up and down and take your time to ensure the transition falls where it is needed. Stopping the lens down by using the depth of field preview can make this easier to see.
Method two
Modern metering systems allow for a simpler method of using an ND grad:
1) With your image already composed in the viewfinder, or on the LCD, slide the filter into place and take your shot using the settings the camera has calculated to be correct for the entire scene.
2) Check your histogram. This will confirm whether the entire highlight and shadow detail has been recorded. If the peak is towards the left or middle of the scale, you have selected too strong a filter, whereas too far to the right or off the scale on the right, means a stronger filter is required.
What to watch:
1) Accurate positioning is important. If the filter is placed too high, the transition will be seen in the sky, too low, and the foreground will have an unnatural “shadow” across it.
2) Avoid using multiple filters. Whilst multiple filters can be used to darken bright parts of the scene further, this increases the number of reflective surfaces in front of the lens, meaning more likelihood of flare and also reducing contrast.
3) Vignetting can be a problem with wide-angle lenses. This is another reason to avoid multiple filters.
4) The filter should be neutral, so it doesn’t introduce any unwanted colour cast. Cheaper filters may have a noticeable colour cast (usually magenta).
Neutral Density Filters
One of the lesser known and underappreciated filters; neutral density filters have great creative potential. Semi, opaque, they are used to reduce the amount of light entering the lens, thereby prolonging exposure times, and making them useful aids when photographing water, clouds, or indeed anything moving when the intention is to convey movement rather than freeze it. The beauty of ND filters is that they allow you to set the aperture and shutter speed you want, rather than that which the conditions dictate. Although they obstruct incoming light, they do so uniformly across the entire frame, therefore neither image colour nor contrast is affected. The effect of the ND filter cannot easily be reproduced digitally.
Types of ND Filters
There are several types of ND available – screw in ones which come in various filter threads and square or rectangular slot in ones which fit into a holder that attaches onto the front of the lens. The screw in type is the simplest to use but the slot in variety, can be used in conjunction with other filters in the same holder. There is also a variable ND filter available, which is screw in, but comes with an adjustable outer ring that you rotate to adjust the density, dependent on the light conditions and the effect you want.
ND filters are available in different strengths, the stronger the filter the more light it absorbs and the darker it appears, for example;
- 0.3/2x – one stop reduction in light
- 0.6/4x – two stops reduction in light
- 0.9/8x – three stops reduction in light
- ‘Big Stopper’/1000x – ten stops reduction in light
So for example, an ND4 will reduce the amount of light entering the lens by two stops. A ten-stop filter will produce an extreme increase in exposure time even in broad daylight making for some interesting creative effects.
When to use ND filters
Water
Using an ND will allow you to capture the flow of water. On waterfalls they prove useful in showing movement of the water to produce a silky effect. This can also be used on seascapes, with crashing waves for example, to produce more of a misty look. The speed at which the water is moving as well as the light conditions at the time will dictate the filter you choose, along with your own personal preference of course.
People
ND filters can be used very effectively to get rid of unwanted people in the frame, for example when shooting in popular tourist spots. As long as they are moving if the shutter speed is slow enough it will ensure they are blurred are not visible in the image. An exposure of a few seconds is needed to achieve this.
To retain aperture
If shooting in bright conditions, it can occasionally be impossible to take a photograph at the aperture and depth of field you desire. For example, if you want to capture a flower and throw the background out of focus, you’ll need a wide aperture, however your camera may well be suggesting something along the lines of F16 or 22 which isn’t going to give you the depth of field you require. Using an ND filter will reduce the amount of light entering the lens, prolonging the exposure, and allowing you to select a wider aperture to give you the result you want.
What to watch
1) Choose with care – as with most things you get what you pay for. Polyester is the cheapest material but gives poorer results, often producing a colour cast, although this can be removed in post processing. Glass is prone to breaking, so the ideal choice is resin.
2) Circular filters are limiting in that they only fit a specific diameter lens, unless you buy step up rings, meaning you may have to buy more than one.
3) Vignetting – stacking of filters can lead to vignetting issues, particularly with wide-angle lenses. Make sure if using a slot-in filter holder, that you buy a wide-angle adapter ring.
Ten Stop ND filters
With a filter factor of 1000x or 10 stops, these filters have become very popular recently, allowing the photographer to slow down their exposure times to the extreme, even in bright light. A 10 or 15-stop filter can produce some very creative effects and is often used to transform the look of clouds, making their movement look like brushstrokes, whilst on water it has a smoothing effect, both of which can add atmosphere. They work particularly well in overcast light when photographing subjects with strong, bold shapes such as a pier and can also lend themselves particularly well to monochrome conversions.
How to use them
As these ND filters are so dense it is impossible to see through them. As such, composition, focusing and employing any other filter, must all be taken care of before one is used. Due to their density, the cameras inbuilt TTL metering will usually fail to select the correct exposure. You will most likely find that you will need to use the BULB setting to manually keep the shutter open as the length of the exposure time required often exceeds the camera slowest shutter speed (usually 30 seconds).
There are a number of apps available which you can download to your phone to help you calculate the exposure needed, otherwise it is a case of working it out manually Take an exposure reading without the filter and then increase the exposure time by 10x eg: 1/15 sec will become one minute with the filter in place.
What to watch
Strong filters of this nature often result in a cool blue cast to the image. This can be corrected in-camera using the white balance adjuster or in post processing. If you intend to convert your image to black and white the cast is irrelevant.
Filters for Black and White Photography
Popular in black and white film photography, coloured filters are still used in the digital world. In black and white photography certain colours can look very similar when converted to greyscale. This can cause subjects to blend into one another, leaving you with an image lacking in contrast and definition, which appears flat and dull.
Coloured filters alter tones and contrast in an image and can be used to great creative effect as you can dramatically change the tone of a colour so that it becomes a darker or lighter shade of grey.
In this way you can control the way your image will appear, allowing you to create mood, balance and contrast, and also enabling you to emphasise the most important parts of a scene. Their most common use is to increase contrast between sky and cloud. Using them takes a bit of practice.
How do they work?
Coloured filters work by allowing certain wavelengths of light through and blocking others from reaching the film or sensor. The filter will let through it’s own colour so those subjects with the same colour or similar to the filter will become lighter whilst subjects with contrasting colours will become darker.
There are 4 coloured filters that are commonly used in black and white photography – red, orange, yellow and green.
Red
Red filters produce a very strong effect and significantly increase contrast. They can be used to produce very bold and dramatic results, particularly in landscape photography where they will turn a blue sky almost black and make clouds really stand out. A red filter will help increase definition between flowers and foliage, which often have a similar tone. A red filter will also penetrate haze and fog making them good for increasing visibility. The extreme effect of a red filter means it can make your image look as if it has been shot through an infrared filter, making it a cheaper alternative to infrared photography. A red filter will make a post box appear almost white and, by blocking blue and green, a blue sky or green tree will become almost black.
Green
This filter affects blue and green, which become much lighter. Orange and red are absorbed and so become darker. It is mainly used for photographing plants as it helps separate green foliage from brightly coloured flowers. It can also be used in landscape photography to boost the appearance of grass and trees as it can help differentiate between greens. On the negative side, it also has the effect of lightening the blue in a sky so you need to be careful as contrast may suffer.
Yellow
A yellow filter absorbs blue, therefore darkening sky slightly and helping to balance its exposure against the darker ground. They also bring out clouds nicely, resulting in greater separation between a blue sky and white clouds and therefore more interesting skies.
It is a gentle filter, giving a subtle change to yellows, oranges and red which all become slightly lighter. Yellow filters are also good for separating shades of green, and so can be used when photographing plants to increase the contrast between foliage. In portraiture, skin tones have a warmer, more natural look.
Orange
An orange filter is a good general-purpose filter. It lightens orange and red and darkens green and blue. Similarly to a red filter, it can be used to reduce the appearance of fog and haze, and to darken skies and emphasise clouds. It produces a stronger effect than a yellow filter but is not as dramatic as the red filter, making it the ideal choice to encompass the effects given by both these filters.
It is also possible to apply filters at the post processing stage when doing a black and white conversion.
