The Kowa 1/2" Zoom Lens with Manual Preset Over-ride (30 to 750mm) incorporates the 3-Cam Design and eXtra low dispersion (XD) glass. This system solves the problem of de-centering which sometimes occur in the conventional pole system. Not only is the movement of the lens impaired by de-centering, but the optical performance suffers too. The 3-Cam Design reduces internal reflection. As a result, the image obtained by this design is sharper. The 3-Cam Design offers higher optical performance and a longer service life.