A UV filter is one of the most important filters to own and it should be available for every lens. The filter blocks the invisible UV rays which can cause a loss of sharpness. The use of the filter is particularly recommended for work in the mountains, at the ocean, and in areas with very clear air. The contrasts are heightened, and distorting fog is avoided. The Opteka HD2 Multi-Coated UV (0) Ultraviolet Haze Filter cuts haze for sharper black and white prints and corrects the blues and violets in color prints. The filter glass is colorless, and hence no increase in the exposure time is required. Multi-coating can prevent light reflection, ghost light, internal reflection etc, making image clearer and sharper. It can dramatically improve image quality. This is specially important in digital cameras. Since the image sensors CCD or CMOS are highly susceptible to reflections, this stray light can ruin your photographs. Multi-coated glass benefit substantially reduced light reflections, resulting clearer image with greater contrast. This type of filter is also eminently suitable as protection for the front lens, and because of its color-neutral properties it can remain on the camera lens permanently. A scratched front lens element can not be repaired; and replacement is costly. Exchanging a damaged UV filter for a new one is more economical than the purchase of a new lens. Advances in high-index / low-dispersion optical glasses, new barrel materials, and exotic anti-reflection coatings, along with the latest in computer-aided-design / computer-aided-manufacturing, are combined to produce lenses of unprecedented quality. Nothing changes the way you see the world like High Definition II, and no company does High Definition II like Opteka. In the professional setting, Opteka's glass optics define High Definition. Change the way you view the world. Enjoy outstanding detail, enjoy enhanced clarity, enjoy Opteka.