What is Zoom & Throw Ratio of a Projector?

Many people wonder, “What is the zoom & throw ratio of a projector?”

Well, the Zoom and Throw Ratio of a Projector is calculated with the distance in which you would want to project your image divided by how large you want it to be.

For example, if you want to project an image at 100 inches wide from 8 feet away, then this would be a 1:4 ratio. If it’s personal preference what size the image should be when projected, then divide your desired width by your desired distance. The resulting number will represent that aspect of the Zoom and Throw Ratio of a Projector.

Why Do You Need to Know About Throw Ratio?

If you have purchased a projector, then there is a good chance that you will be watching movies on it. Why?

Well, for one thing, it’s technology. For another thing, it’s the trend these days to go with a Movie Theater Experience instead of a Home Theatre Experience in the living room.

A Movie Theater Experience is usually comprised of large screens with lots of brightness and brightness controls that are at the mercy of theater technicians who want you to enjoy an optimal viewing experience in your home theater.

However, for a home theater enthusiast, this is usually not desirable because of the level of luminance and contrast that you would experience if you went to see a Movie Theater Experience at night.

Now, with most projectors being capable of displaying an image at high resolution from long distances away, it opens an interesting new path in the evolution of Home Theater.

Why Do You Need to Know About Throw Ratio?

If you can project an image from far away (without compromising quality or resolution), then the ability to create truly great large-scale movie experiences can easily be achieved and it’s up to you to make them happen. It’s no longer dependent on your theater, but on your needs.

For example, if you have a screen at 10 ft wide and it’s 80 inches high, then you can use an 85″ diagonal projector instead of a larger screen with an 85″ diagonal projector and still have the same viewing distance and size as that larger screen.

The projector with the higher zoom & throw ratio would give you better image quality during dark scenes because it won’t have to work as hard to project light onto the larger sized image than if it were working on a smaller screen from more of a distance.

It also means that you don’t need to compromise personal preference for viewing distance when it comes to selecting your screen size or your preferred throw ratio range.

How to calculate the throw ratio?

Throw ratio is the most important factor in your projector setup, and it’s the number one deciding factor when you’re purchasing your first projector or if you’re upgrading to a new projector.

The throw ratio of a projector is calculated by dividing the distance from the lens to where you would like to project your image by the width of that projected image. For example, if you want an 80″ image at 10 feet away (throw ratio of 1:8), then this would be an example of 4 x HD resolution (1080p).

How to calculate the throw ratio?

In most cases, you will want a throw ratio of less than 1.5:1. This is because the higher the throw ratio, the less bright and washed out your projected image will look; on the other side of it, if you have a lower throw ratio then your projected image will appear brighter and crisper.

You need to keep in mind that just because an image is 4K or 1080p doesn’t mean that it’s going to look the same on a 4K UHD TV as it would on a 1080p HDTV if you were projecting that image onto those different screens.

Why throw ratio is important to factor for the projector set up?

Throw ratio is so important because it helps to determine the brightness of your projected image when you’re putting together a good projector setup. If there is no throw ratio involved, then you will have to crank up the luminosity settings and that would literally blow out the image.

And if you do have a throw ratio, then it can either make or break your projector setup because it will make the difference with how large of an image that you can project and still get a good picture without having too much brightness for dark scenes or too much darkness for bright scenes.

Why throw ratio is important to factor for the projector set up?

Now, there are some things you should know about. For one, if you’re screen is more than 3 feet away from the lens, then you’re going to need a higher zoom & throw ratio because you will probably experience a lot of light spill due to the increased distance.

This can be dangerous and possibly cause an accident, so make sure that your screen is no more than 3 feet away from your projector. You’ll also want to keep in mind that if you’re getting off of the 16:9 aspect ratio and going into a 2.39:1 aspect ratio then your throw ratio is going to be lower.

Why Do You Need to Know About Zoom?

So the second number that is just as important as the throw ratio when it comes to choosing your projector is the zoom ratio.

Why Do You Need to Know About Zoom?

The zoom ratio is measured by dividing the focal length of a lens by its effective aperture. The focal length of a lens is the distance from the center point of the lens to the optical axis, and the effective aperture refers to how large that projected image will be at any given distance from your screen.

In other words, if you have a 50mm focal length and an f/2.0 aperture, then this would mean that you’re using an HD resolution and you can project an image at 100″ diagonal (based on 16:9 aspect ratio).

In most cases, you’re going to want to go with DC or Digital Cinema Zoom. This is because it allows you to have a large zoom ratio while still maintaining your contrast ratio and brightness, and these are two things that are extremely important to your overall viewing experience.

What is the purpose of digital zoom?

Digital zoom has long been used by those who aren’t quite familiar with the benefits of actual optical zoom.

Digital zoom is used for phones and tablets, so why do we use it for projectors? Well, some people would rather have a larger image even if the quality isn’t exactly up to par; so, when this happens you will see things start to pixelate or jitter around on the screen at higher resolutions.

Benefits of Zoom Ratio

The reason why finding out the zoom ratio of your projector is important is because it will enable you to choose a screen size that will be easy to use with your setup. For example, if the zoom ratio on your projector is 1.2x then you’re going to need a screen size of at least 100″ before it becomes too large for your setup.

The other benefit that comes with knowing the zoom ratio is that you’ll have an idea of how far away from the screen you can stand while still getting a good and clear picture because it takes into account this distance away from the screen as well as how close you are from the lens when measuring your zoom ratio.

What is the purpose of digital zoom?

Variable Zoom Range

If you plan on creating a home theater setup, you’re going to want to invest in a projector that has a variable zoom range. Why is this important?

Well, it will allow you to move the projector back and forth between two different screen sizes without losing any quality in your image.

Many projectors have a minimum zoom range of 1.0x and they can go up to at least 1.5x or 2.0x depending on the other specs of the unit; so, if you want to have more wiggle room then be sure that your unit has at least 2.0x and if possible try and get one with 2.1x or higher.

For example, say that you want a projector that can go from a 100″ screen to a 180″ screen with a 2.0x zoom range. Then the bigger the zoom ratio is, the easier it’ll be to have this ability because you’ll lose less quality in your image as you can keep the projector closer to the screen and it will still deliver great quality images.

Throw Ratio vs. Zoom Ratio

Throw Ratio is what most people actually want when they’re trying to get an idea of how large the projector will be.

Throw Ratio is mostly designed for reference and this means that it can only be used in conjunction with a number of other specifications. If you’re not sure about any of those other specs then just disregard the Throw Ratio as it’s more or less useless.

One last thing, a throw ratio tells you how far away from the screen your projector is going to have to be and this is another reason why 2.1x zoom ratios are desirable because they can go even closer to the screen than 1.0x zoom ratios (provided they don’t have lens shift).

There are several methods to increase the field of view. In addition to optical zoom, there are digital zoom and focus-assist (or autofocus).

Throw Ratio vs. Zoom Ratio

Digital zoom technically enlarges the image by interpolating pixels in order to enlarge the appearance of objects closer to the camera.

In other words, it’s a magnification technique. You can buy a lens with this function for very little money, but normally they don’t provide consistently acceptable quality and are inferior in terms of sharpness and contrast.

In contrast, many autofocus lenses have an electronic system inside that automatically moves the focus from one point in the image plane towards another as you move your camera or as you shift your focus from one object to another.


If you are going to invest in a projector setup, then you will want to make sure that everything is in its proper place; otherwise, it’s going to be one lower-quality viewing experience that will have you regretting your decision.

If the image is too dark during a bright scene or too bright during a dark scene then the image quality of the entire movie is going to be affected.

In most cases, a high throw ratio and digital zoom on your projector will give a better end result because it’s capable of producing an image with more brightness and contrast than projectors with lower throw ratios and digital zooms.

In order words, it will make the resolution more important when it comes to selecting projectors for home use.


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