Why put a UV filter on a camera lense?

Question

Duh Micheal I mean how will it effect my camera/photos if I don't put one on.

Answer 1

They help with color and sharpness, which can be distorted by UV light.

Answer 2

The basic reason for doing this in FILM cameras is to remove invisible Ultra Violet light which tends to make film images have an undesirable bluish tone on the slide/negative.  This is not as significant of a problem on digital cameras because it can be compensated for much more easily with software processing.

The secondary reason has generally been to "protect" the lens.  This is a valid reason on ANY camera but there are PROS and CONS of this choice -

PROS -

Effective at keeping dust, moisture and scratches from occurring on the front surface of a lens.

Protects delicate lens coatings from damage.

Reduces post processing when high amounts of UV light are present.

CONS -

May cause decrease in image quality if filter is badly aligned or low quality glass.

May cause undesirable change in the optical properties of certain lenses.

In RARE cases could damage glass elements of lens if filter is broken while mounted on camera.

My opinion -

I have thousands of dollars invested in lenses.  Dust, sand, dirt and moisture are the most common problems with any of these lenses and a filter that costs less than 5% of the value of most of my lenses has saved several of them.  In forty years I have had to discard 2 or 3 filters because they were damaged to the point of becoming unusable.

On two occasions I have dropped lenses; one was damaged beyond repair (as was the filter) although I could still use the lens for limited photography (the zoom wouldn't work).  In the other case I dropped the lens on a sandy roadside, the filter was scratched beyond repair and the lens was contaminated with sand and debris but the lens surfaces were undamaged and a thorough cleaning and adjustment saved a $120 (1968 dollars) lens.

I keep a UV filter on most of my lenses at all times UNLESS I am shooting something where I am very sure that dust and moisture are not a problem AND I have some reason to think the filter might compromise image quality.

HTH.

Answer 3

to do just what it says. Filter out the ultra violet rays