What It Is
A lens shift allow your projector lens to move up and down or left and right within the housing of the projector. Basically your projector lens has a little bit more space to be adjusted. This shift can be done manually, but the best projector lenses control this feature by remote control.

Advantages
One of the most obvious benefits of a projector lens shift is the flexibility it affords in the installation. It cuts down on the normal time it would take to measure the exact angles and distance that your projector should be at. It also provides more leeway for first time do it yourself home theatre set ups.

In addition, if you have an existing mount from a previous projector that you would like to use chances are the dimensions will not be exact. For example, your last projector may have had the 8mm projector lens in the center of the unit, whereas your new projector has the lens slightly off center. The projector lens shift allows you to make the necessary adjustments so that you can use the old mount with the new projector.

Also, a discount projector lens with a shift will allow you some flexibility when deciding where to place your screen. For example, instead of having to hang your screen at the exact height dictated by the drop extension pole of your ceiling mount, you can hang your screen at the height you desire and compensate for the difference using the lens shift.

Another benefit is that even a cheap projector lens shift will produce a superior image quality that a digital keystone correction. This is because a keystone correction actually compresses the image and recreates portions of it. This type of adjustment works fine for still pictures, but for moving images a projector lens shift will provide better picture quality.

A projector lens shift also can be a easy fix for people who have made the mistake of purchasing and installing both there screen and mount before the actual projector. These people have limited their choices in projectors they can use and often rely on the lens shift to give them the versatility they need.

Comments
While a projector lens shift may not be necessary at all if your projector is installed to the correct specifications, you should still consider it a beneficial feature when purchasing a projector. It will provide you with flexibility now and in the future and simply the installation process for you.