It’s common for people to think only one lens is used in a projector. The truth is every projector uses multiple lenses.
In most projectors, you can even change them around to get the picture you’re looking for.
Mind blown, right?
Before you do that, there’s a lot of things you need to know.
Let’s look at the 4 main types of lenses, and which projectors they can be used in.
Different Types of Lenses
Every projector already comes equipped with preselected lenses, but if you’re looking to change things up you need to know the specifics of which lenses are used in projectors and which ones will help you get the best quality picture.
Convex (Zoom) Lens:
You’ll find a convex (zoom) lens in a projector no matter what model it is. It’s the most basic requirement for a projector to deliver a picture because it enlarges the projected image size.
This gives you the capability to place or mount your projector wherever you want, and that’s a standard trait of projectors these days since everyone’s house, office, etc. is different.
Without this lens, the only way to adjust your picture would be by moving your projector back and forth until you find the sweet spot, and that could be really frustrating.
Even though this is basically the principal lens, they can have a range of zoom capabilities. The bigger the zoom factor, the bigger you can make your picture.
For example, a lens with a zoom factor of 1.2X will allow you to increase the picture size by 20%. That’s acceptable in most cases, especially if you’re using a projector to set up a home entertainment system.
Even if you have a fixed screen you’re trying to fill, a limited zoom range can make the fine-tuning process a lot easier.
Short-Throw (Wide-Angle) Lens:
This might be obvious, but a short-throw lens is most commonly found in short-throw projectors.
A lot of people buy short-throw projectors because they simply don’t have the room for a 10-foot distance between the projector and the screen.
You can put a wide-angle lens in any model projector, but it’s not recommended. It’s a possible alternative if you have to move your standard projector closer to the screen, but the lumen (light power) of your projector doesn’t change and you can end up with hotspots and distortion.
A short-throw (wide-angle) lens has a short focal length, thus producing a wider field of view. Basically, it creates the distance between the picture and the projector that it physically lacks.
Since short-throw projectors are anywhere from 0 to 8 feet from the screen, the close range would naturally make the picture appear a lot smaller or cut off parts of the projection. A wide-angle lens creates a wider frame to ensure your entire picture is seen.
On the flip side, there’s the long-throw lens. By the title, you would think that a long-throw is the opposite of a short-throw, but that’s not the case.
When a projector can’t be positioned close to the screen, an interchangeable long-throw lens is used to get the best-quality picture and works similar to a zoom lens. Since the projector is further away, the lens will enhance the picture in size and clarity on your screen.
Usually, you’ll find them being used in auditoriums, churches, or anywhere that entails a large audience because the projector will be placed behind them.
That’s not to say you can’t use these lenses at home. Anyone that needs a distance of over 10 feet between their projector and screen can use a long-throw lens.
Any type of standard projector can have this kind of lens. That is, any model that’s not a short-throw or ultra-short-throw project can use a long-throw lens. For obvious reasons, they wouldn’t be compatible.
Micro Lenses are very- extremely- small lenses. They generally have diameters less than a millimeter. To put that into perspective, a millimeter is about the length of a single staple.
These lenses can give amazing picture quality and are a great option for digital projectors. Most digital projectors are compatible, but not all of them.
Since the design is so small, the pieces that support the lens inside your projector are usually thicker than the lens itself. If you want to try using this type of lens, it’s important to take this into consideration and make sure it will fit.
You also have to know if you want one with a spherical convex surface, or a more sophisticated aspherical surface. The difference?
A micro lens with a spherical convex surface means the lens has a single layer that curves outwards toward the screen and refracts light. Translation: it collects light and focuses it onto your screen.
An aspherical micro lens has multiple layers and may be thicker. The layers work together to brighten and clarify your picture. Think of it like prescription eyeglasses. When you put on a thick pair of prescription glasses, your view becomes super clear and enhanced. Same concept.
There’s also a special feature on projectors called Micro Lens Array (MLA). It’s used alongside a micro lens to redirect light that would otherwise be lost inside the projector through the prism and out of the lens.
By doing this, you can increase the brightness of your picture even more while reducing the heat generating inside your projector.
What Else Should I Know?
We’ve gone over the different types of lenses and what they’re used for. We’ve gone over which projectors can use each type of lens. So, what else is there to know?
As you know, there’s a million different types of everything there is in the world, and the same goes for projection lenses. Even though you know the main type of lens you’re looking for, you need to know how to choose the specific version of that type.
I know what you’re thinking. There’s way more to it than just knowing the basics of which lenses are used in projectors.
But you want the best results you can get for that awesome home theatre you’re building, right? Right.
So, the next step is to figure out the throw distance ratio of your projector.
Each lens is designed to enhance your picture, but if you pick the wrong one because you’re not sure of your projector’s ratio, then you’re going to end up with bad image quality and have to start all over again.
Or worse- you’ll break something. I know this from personal experience.
The throw-to-width ratio (not a very creative title) will narrow down your options significantly and is very easy so if you’re not a fan of math, don’t worry.
- Determine the throw distance of your projector. Hint: It’s printed on your device. Another hint: it’s the distance in inches from your projector lens to the screen.
- Determine the screen width in inches.
- Divide the distance by the width and that’s your ratio.
For example: A 10’ distance (120 inches) divided by an 8’-wide screen (96 inches) = 1.25. The throw-to-width ratio is 1.25:1 and that’s what you should be looking for in your lens of choice.
If you have a screen that varies in size, you can use the ratio above and determine the throw range. You’ll use the minimum and maximum widths of your screen and make two calculations.
The difference between each ratio is your range and any lens that matches that criteria is compatible with your projector.
Do yourself a favor and don’t try to force a lens that doesn’t match your ratio or isn’t in your range. If the type of lens you want doesn’t meet your ratio, then you won’t get a quality picture no matter what kind of lens it is.
If you find yourself in that predicament, there are companies that do projector lens customization. By reaching out to an expert, you’re more likely to get exactly what you want in a lens without the uncertainty of whether it’s compatible with your projector.
If you just read the line above and thought, “there’s more I need to know?!” throttle back a bit. I’m not going to throw much else your way.
I just want to relay some last-minute tips on you before you decide you know everything about which lenses are used in projectors.
If you’re going to change out your projector lens, do so with caution!
To be honest, you should only remove the lens only when necessary. Let a professional swap out your lenses since they’ve been trained on handling the equipment.
If you don’t go to a professional, make sure the projector is not on and the front is not facing up when you remove the lens. This helps prevent dirt or dust from entering the projector, and you’ll avoid lowering the projection quality.
Feel free to reference this guide any time you’re considering a new lens for your projector. Go through the different types of lenses, find what piques your interest, and look at what will be compatible with your equipment.
And that’s it! I promise.