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Understanding Projector Throw Distance:Why buy an additional lens when the projector has a standard one included?

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Understanding Projector Throw Distance:Why buy an additional lens when the projector has a standard one included?

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In the world of projectors, understanding the term "projector throw" is essential for achieving the optimal display in your desired setting. The projector throw refers to the distance between the projector and the screen, and it plays a pivotal role in determining the size and clarity of the projected image. As you venture into the realm of projection systems, you may encounter the need to purchase a lens separately, leading to the question: What is a projector throw, and why does it necessitate a separate lens purchase?

Projector Throw: The Basics

Projector throw is essentially the distance required for a projector to cast a particular image size onto a screen. It is measured in feet or meters and is a critical factor in determining how far or near the projector needs to be positioned for an optimal display. Projector throw ratios express this relationship by indicating the amount of throw distance required to achieve a specific image width.

Throw Ratio = Throw Distance / Image Width

For example, a projector with a throw ratio of 2:1 means that for every 2 feet (or meters) of throw distance, the projected image will be 1 foot (or meter) wide.

The Need for Separate Lens Purchases

Now, the reason why projector throws often lead to separate lens purchases lies in the diverse requirements of different installation scenarios and the flexibility needed to achieve the best projection outcomes.

1. Customization for Varied Throw Distances:

Different venues present different spatial challenges. Some environments may have limitations on how far you can place the projector from the screen, while others may allow for more flexibility. By offering separate lenses, projector manufacturers empower users to customise the throw distance according to their unique needs.

2. Lens Options for Installation Versatility:

Standard lenses that come with projectors are designed to meet common throw ratio needs, for example most are 2:1 or less. However, for users seeking more versatile installations or dealing with physical placement constraints, additional lens options become necessary. Separate lenses, such as short-throw or long-throw lenses, provide the flexibility to adjust the projector's position without compromising on image size.

3. Specialized Applications and Features:

In specific applications, such as large auditoriums or immersive museum displays, precise control over throw distance is crucial. Separate lenses may offer advanced features like motorized zoom, focus, and lens shift, allowing for seamless adjustments without physically moving the projector.

What We Consider When Choosing a Lens

When faced with the decision to purchase a lens separately, several considerations come into play:

1. Compatibility:

Ensure that the lens is compatible with the throw ratio requirements of your specific projector model. This information is typically provided in the projector's specifications.

2. Installation Constraints:

Consider the venue and installation constraints. A short-throw lens may be suitable for confined spaces, while a long-throw lens may be necessary for larger auditoriums.

3. Image Size and Quality:

Different lenses can impact image size and quality. Choose a lens that aligns with your preferences for brightness, clarity, and the desired size of the projected image.


In conclusion, the concept of projector throw is fundamental to achieving an optimal projection experience. While it may require an additional investment, purchasing a lens separately provides the adaptability needed for diverse installation scenarios, ensuring that your projection system is tailored to the unique demands of your environment. Before making a purchase, carefully review the projector's specifications, consider your venue's characteristics, and choose the right lens to unlock the full potential of your projection setup.

Many projector manufacturers have a ‘lens calculator’ on their website making simple the task of selecting the right lens.

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