The use of screen projectors previously was plagued with the
absolute need to have the projector centered vertically and horizontal on the projection screen
to avoid having otherwise great looking rectangular images and graphs turn into unattractive
trapezoids. Lens shift was developed to eliminate this problem, add flexibility in presentation projector
placement, and let presenters focus more on the content of the presentations rather than figuring
out how to make the equipment cooperate.
What is Lens Shift?
Lens shift is exactly what it implies: the physical shifting of the projector lens within the
projector. Although this does give presenters increased flexibility in where they
position their presentation projector, they should keep in mind the degree of lens shift.
Lens shift was designed to correct placement problems in most situations, but it does have its
limitations and boundaries. Some presentation projectors will correct (or shift) the image
more so than others, so a little research might be required if you think you might be faced with
more extreme presentation environments.
Lens Shift Types
Lens shift can be horizontal (left to right), vertical (up and down), and many
screen projectors are beginning to offer variable lens shift on their newer models
that would allow you to even shift on a diagonal. Although vertical lens shift is the most common type of lens shift, there is an increasing demand for horizontal and variable lens shift as well.
Should I Look for a Presentation Projector with Lens Shift, Keystone Correction, or both?
Lens shift is typically preferred to keystone correction. This is because
keystone correction is a result of the projector digitally correcting the image within
the presentation projector and then displaying the image rather than manipulating the lens.
Because of this, image quality is lost when using keystone correction. Although it is a great
feature, it is not recommended to rely on it too heavily if you plan to use your projector to show
video or use it in a home theater set up because it can create noticeable artifacts in the
corrected image. For displaying text and static images (such as PowerPoint slides), using
keystone correction in your projector is a perfectly acceptable way to correct distorted projections.
You can read more about this our article about keystone correction. |
