How UV Filters Work

Welcome to Plumtree Photo.  This is one of a series of articles describing in depth the products that we sell.  The reason for these articles is to help you make a more informed decision when purchasing accessories for your photographic needs.  If you still have questions about this product after reading this article please feel free to contact us.

Pretty much anyone looking at this knows that a UV Filter blocks ultra violet rays from your photos.  This article will attempt to explain what ultra violet rays are and why you would want to block them.  We will also help you determine what size filter you will need for your lens.

Visible light is measured in nanometers (nm) and ranges from red to violet with red having the longest wavelength and violet the shortest.  Light with a wavelength longer then red is called infrared and light with a shorter wavelength then violet is called ultra violet.

So why do we want to block ultra violet rays?  Color film has three layers of sensitivity, one to red light, one to green light, and one to blue light.  If there are a lot of ultra violet rays around where you are shooting the blue layer of sensitivity in your film will get extra exposure and your photograph can take on a blue color as in the photograph below.

Without UV Filter                                                              With UV Filter

One of the biggest factors affecting the amount of UV rays around is altitude.  At sea level there are not a large amount of UV rays because they are scattered by the atmosphere.  The higher up you go, the thinner the atmosphere, the more UV rays are present.  That is why this photo of Cook Summit has quite a bit of blue tint without the UV Filter attached.

Digital sensors are not as sensitive as film to ultra violet light, but they can be affected especially in the winter when the snow is reflecting UV rays.  Digital sensors are sensitive to infrared light, but most digital cameras have infrared blockers built into them.

The other main use for UV Filters is as a protective sheild for your expensive lens.  If the glass on your lens is scratched or damaged you cannot replace just the one scratched piece.  The entire lens is ruined and needs to be replaced.  Today's high quality lenses can cost hundreds, even thousands of dollars versus less then $15 for a UV Filter at Plumtree Photo.

What is the difference between a UV and a Skylight Filter?  Both will block ultra violet light but a UV Filter is clear glass while a Skylight Filter is pinkish and may produce a warming effect in your photographs.

At Plumtree Photo we carry the following sizes of UV Filters.

52mm   55mm   58mm   62mm   67mm   72mm   77mm   82mm   86mm

If you know the size filter that you need please click here to go to our listings for UV filters.  If you are not sure of the size you need please click on your camera's logo below to go to our lens chart for your brand.