Photography for beginners: Filters

Filters are pieces of glass that screw onto the front of your camera, and they can cause all sorts of unusual effects to your photos.

The good news is that you can buy filters cheaply from eBay (and of course, less cheaply from the high street, if that’s how you like to buy). Before buying, you’ll need to know the diameter of your camera’s lens. This should be written somewhere on the lens barrel or often around the glass on the front of the lens. Look for something like Φ58mm, and then check that your lens has a fine screw thread inside the rim. You’ll need this for the filters to screw into.

Of course each camera (and potentially each lens, if you have an SLR) may have a different lens diameter. If you’ve built up a large collection of filters and you plan on changing camera, never fear! You can buy adapter rings that allows you to use the “wrong” size filters on your new camera.

So let’s have a look at the various kinds of filter you can buy. This list is by no means exhaustive!

Ultraviolet (UV) These filters are designed to filter out UV light, which is invisible to the eye but can cause haze in outdoor photos.As they are so cheap, it’s worth keeping on one the front of your camera permanently to prevent the lens from scratches.
Infrared (IR) IR filters remove all light except infrared light. It can give an eerie night-vision type effect, or give interesting photos of hot objects – such as the sun or a light bulb. Example.
Neutral Density (ND) ND filters simply cut down the amount of light entering the camera. Think of them as sunglasses for your camera. With an ND, you can set a longer exposure in daylight, or it allows you to keep the same shutter and open the aperture a bit wider for increased depth of field.ND filters come in a variety of darknesses. The most common types are ND2, ND4 and ND8, which allow through 1/2, 1/4 and 1/8 of the light respectively. If you’re not sure which to buy, try an ND4 first.
Circular polariser (CPL) Polarisers cut glare from reflective surfaces such as glass or water, and enrich the colour of the sky.
Soft focus / diffuser These filters add a gentle blur which can improve the appearance of skin in portraits, or add a slightly dreamy feel.
Graduated ND (GND) These filters are almost clear at one edge, and dark at the other edge, fading slowly across. You can use a graduated ND to darken and enrich the sky while leaving the foreground unaffected.
Star These filters cause points of light to appear as stars. You can get them in 4-point or 6-point varieties.
Skylight Skylight filters reduce the bluish tinge that can occur when shooting in daylight.
Graduated colours These are graduated filters with a colour. The most common ones are blue and orange – for emphasising the colours if the sky during the day, or at sunset.

These are the rules of thumb that I’ve come up with through experimentation. Hopefully they’ll be useful:

  • Always keep a UV filter (or at least some other type of filter) on the lens to prevent scratches
  • Consider replacing the UV filter with a Skylight filter when shooting outdoors to avoid a blueish cast
  • Use an ND filter when shooting in very bright light to avoid overexposed areas
  • Use a CPL or a GND when shooting landscapes with large areas of sky, to make the sky dark and rich
  • Consider using a diffuser when taking close portraits to soften skin tones
  • Any of the other filters are generally for novelty effects and are not subtle
  • Try to use only one or two filters at any one time. Every filter you add can decrease the quality of the lens system, and if you stack up three or more filters, you can usually see the rim of the filters in the photo.

So if you fancy trying something different, I recommend getting some cheap filters from eBay and seeing what interesting effects you can come up with.

Next time, I will write about basic photo editing on a computer.

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