The Vivitek 1.72-2.27:1 Standard Zoom Lens allows you to change the focal length, which enables a range of projection distances. It has a zoom ratio of 1.3:1 and a standard-throw ratio of 1.72 to 2.27:1.
Installing a zoom lens affords greater flexibility since you can alter the projection distance without actually moving the projector. This is convenient for permanently installed projectors. You can compensate for miscalculations during installation and it's possible to adjust your display proportions depending on class size or type of presentation.