What is "throw distance" and how does it work?

One of the most important concepts to understand when using digital projectors is "throw". 

Simply put, "throw" describes the size of your projected image.

Here is a primer on how "throw" will affect your digital decorating experience. 

Throw Distance

"Throw distance" measures the distance between the lens of your digital projector and the projection surface. 

For example, if you are setting up a window decoration, the distance between the Window Projection Material and the lens of your projector is your "throw distance".

Short Throw vs. Long Throw

Digital projectors are often categorized as being either "short throw" or "long throw" projectors.

A "short throw" projector is designed to use a short "throw distance", which creates a large image when the projector is close to the projection surface.

Digital decorating usually works best with a "short throw" projector, depending on your particular set-up.

A "long throw" projector is designed to use a long "throw distance", which creates a large image when the projector is far away.

Movie theaters use "long throw" projectors. These projectors are usually not as useful for digital decorating because the projector needs lots of distance to fill up your projection surface. However, this all depends on the particulars of your environment.

Throw Ratio

The easiest way to measure the potential throw distance of your digital projector is to determine its "throw ratio".

To make an example, let's say your projector has a "throw ratio" of 1.25':1'.

The first number represents the number of feet of distance from the projector to the screen. 

The number after the colon represents 1 foot of screen width. 

This means every 1.25 feet of distance between the projector and the projection surface will create an image that is 1 foot wide.

The Throw Distance Calculator

Epson published a tool which we find very helpful for understanding specific throw distances.

Click this link to see the Epson "throw distance calculator".

While you are planning your decorations or shopping for projectors, it can be incredibly helpful to plug your own numbers into this calculator. 

The calculator can help you develop an idea of what "throw distance" will work best for you.

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