A beginner's guide on using camera filters
How to use filters and what they do
Filters are placed on the front of the camera lens, providing additional protection as a side effect. It’s crucial to make sure that the thread size of your filter matches the lens. Depending on your filter, you can avoid or enforce reflections, intensify colours or achieve professional time exposure.
This is your most important type of filter. Polarising filters avoid unwanted reflections on smooth surfaces such as glass or water. They also intensify colour and contrast. This effect can be seen clearly with pictures of blue skies or green plants. If you want to make sure your pictures boast blue sky, strong colours and only those reflections that you’re looking for, get a polarising filter.
With and without polariser – source: www.photographyblogger.net
ND filters reduce the amount of light passing through the camera lens. These filters are often used for time exposure or when taking pictures in bright light conditions with a large aperture. They’re also popular in videography to set the right length of exposure when filming in bright sunshine. ND filter is short for neutral-density filter. These types of filters are also called grey filters. They come in different levels of optical density, which affects the time of exposure. An ND1000 filter, for example, causes a tenfold f-stop reduction.
Source: Matthias Widmer
Have you ever wondered what all those filter terms and names mean? Here’s a table for your overview. Hoya names filters after the lengthening factor of shutter speed, most other filter brands, however, name their lenses after their optical density (ND or NDx). This table also shows by how much the shutter speed is extended, how high the fractional transmittance of each filter is and what the effect is on the focal ratio.
UV / protective filters
The Sigma filter below was hardened using a special procedure, offering great quality and guarding the front of a lens from impact and scratching. It’s important to opt for quality with protective lenses to make sure image quality isn’t affected and you can make the most of the lens.
Nowadays, UV filters are only used as lens protection. UV flare used to cause colour films to get a blue cast, which was especially noticeable with pictures of mountains or the sea. Modern digital camera lenses, however, are able to filter UV light and avoid blue cast. Nevertheless, it makes sense to use a protective filter, especially in dusty conditions and to protect the front lens.