The ET-D75LE30 zoom lens allows you to vary projection distance by adjusting the focal distance. It has standard-throw ratio that fluctuates depending on the aspect ratio of your projector. Installing a zoom lens affords greater flexibility. You can compensate for miscalculations during installation and by changing the projection distance with your zoom lens, it's possible to adjust your display proportions depending on class size or type of presentation. Designed for use with 3-chip DLP projectors.