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Filters fit over the front of your lens to provide control of colour or special effects.
They might do something simple like reduce light or glare.  They can be used to add or remove colour.  They can be used for weird effects like creating kaleidoscopic images.

Skylight Filter


 The first filter you might want to get is called a "UV" or "Skylight".  This cuts down ultra-violet glare from sunlight.  While the effect is minimal many photographers keep them permanently on their lens to provide a measure of protection.   Much better to scratch a 20 filter than an 800 lens.
Other photographers will tell you this is madness; that you are reducing the quality of your 800 lens to that of a 20 filter.  Personally I always keep a UV filter on my lenses and this has saved me serious damage to a lens.

Polarising Filter


A polarising filter works like Polaroid sunglasses.  It cuts down some light and reduces reflections.  It is normally used to darken down skies, reducing them from white to blue.
You need a rotating polarising filter.  This is because the effect of the polariser is dependent upon the angle of the light at the filter.   The effect is strongest when light comes over your shoulder to one side.  It is non-existent when shooting into the light.
To use a polariser look at the scene through the viewfinder.  Rotate the polarising lens until the effect is at its strongest.  Take the picture.   You need to do this every time; a change of angle will completely change the effect.  On some lens focussing or zooming the lens will also rotate the filter.

See how the polariser (effect on right) has reduced glare in the sky and brought extra colour and saturation into the landscape.
© Spencer Thomas

A Neutral Density Graduated filter.  Darker at the top, clear at the bottom.

Neutral Density


A neutral density (ND) filter just cuts down the light.  Now that might seem a little odd, when often there is not enough light around.  But if you want to get a slower shutter speed - for example shooting "milky" waterfalls - then the neutral density filter will help you.   They are described by how many stops of light they reduce.  They are often stackable, so you can use several in combination to really cut out light.

Graduated Density Filter


This is like a neutral density filter, but graduates from dark at the top to nothing at the bottom. It is often called an ND-Grad (Neutral Density Graduated). You would use this to cut down brightness in the sky without affecting the foreground. A classic case would be shooting a wedding party with sky behind. The graduated density filter keeps the sky looking blue, not exposing into white.

An ND Grad has been used to fine effect here, with deep, dark and dramatic skies and a slow shutter speed giving the water a lovely sense of motion.
© Richard Taylor

A tobacco graduated filter has put lovely orange tones into the sky but left the grass green.
© Gopal Vijayaraghavan
There are also colour graduated filters.  For example, a deep blue at top fading to clear.  Again this is used for giving blue skies.  Another common version is the tobacco filter that gives lovely warm sunset tones in the sky.

Soft Focus Filter


A soft filter (or diffusion) filter is strongly associated with romantic images. It works by spreading highlights in the image creating that soft look. You can achieve the same effect by spreading Vaseline on plain glass filter, or just using a piece of material cut from stockings or tights.

A lovely soft "barely there" portrait
© Jennifer Juniper J'Anet & ...

Six point starburst for a simple but effective concept.
© Benson Kua

Star Burst Filter


Gives you lovely twinkles from sharp points of light. It looks a little old fashioned now, which probably means it will be back in fashion next year. Star bursts are defined by how many rays of light come for the light source, 6,8,12 or more.

Close-Up Filters


A handy and quite cheap way of getting a close-up focus when your lens does not normally support it.  If you are serious about close-up you really need a proper lens as the quality of most close-up filters is not great.   But handy if you only have an occasional use for it.

Colour Filters


Filtering for colour breaks down into two types:
  • filtering for correction;
  • filtering for effect.
In old-school film days you could not change the colour balance of your film, so if you were shooting in artificial light you would use a filter to compensate.  Now your camera does it for you and corrective filters are not used that much.
When filtering for affect you are typically looking to warm-up or cool-down an image.  So a warm, orange or cool, blue filter is used.

Colour Filters and Black and White Photography


This might sound odd at first pass, but a colour filter can let you control how a black and white image looks. For example a red filter lightens red tones but darkens green tones. A black and white picture of a tree with a red filter will give strong, dark leaves.

The red filter has really darkened the trees for greater contrast.
© Calgary Reviews

Filters and Software


Many of these filters are no longer used, because the effect can be easily reproduced in software on your computer.  This means you do not need to commit to a particular treatment until later.
If you shoot in RAW mode then you have a huge range of filtering options that are very effective.  A RAW file contains extra information that you do not normally see.  But using software filters you can bring that information back into your image.
For example you can add neutral density and colour correction filters afterwards.
 If you shoot JPEG then your range is slightly limited because a JPEG files does not contain quite the same level of extra information.  Nevertheless nearly all the same options and flexibility are open to you.

There are a few filters that cannot be easily reproduced in software.  The polarising filter is the main one.  You cannot use software filters to reduce reflections, glare or put natural colour back into skies.
The ND and ND-Grad filters change what the camera records.  Although you have some leeway with brightness in software an ND filter might be the only way to get the original base image.
 Star burst filters are one of the few special effects filters I've never seen well done in software.
 Beyond that there are more filters, both sensible and bonkers available in software than you can ever imagine.



If you have any of these filters, then practice with them.   What do you need to do to achieve the strongest effect with a given filter?
If you don't have any of these filters then try these:
1) Stretch stockings or tights over the lens
2) Stretch cling film over the lens
3) With the cling film, make a hole in the middle of the lens
4) Use a coloured, see through sweet wrapper or similar over the lens
Find out what size filters your lens requires.  Have a look online and see how much different filters might cost.