Do You Need a Screen for a Projector?

Being able to project an image on any flat, or flat-ish, surface is one of the greatest strengths of any projector. Most modern projectors have built-in streaming and at least passable speakers, so you can binge-watch TV series from just about anywhere. That's the pitch, anyway, but the reality is a bit different. 

Unless the surface is perfectly smooth, you're going to see that texture of what the image is projected on. Also, painted walls change the image's colors, and all but the most perfect white surface will absorb a lot of light, something no projector has in abundance.

So what about an actual screen? Movie theaters, after all, don't just project onto a blank wall. At their simplest, screens can create a smooth, reflective surface to help your projector look its best. More complex screens can reject ambient light, focus more of the light from the projector back to you (making the image and hence, the projector seem brighter), and more. 

Given the extra cost, not to mention the added complexity of setup and mounting, is it worth getting a screen? Not to get all spoiler-y, but to put it simply, yes. Here's why.

To screen, or not to screen

There are three main reasons to get a screen:

• Brighter image: Even simple screens are better than walls of any color.
• Smoother image: Walls have texture that will be visible in the projected image.
• Potentially better contrast and overall image quality: Some screens can "focus" more light toward your eyes, making the image seem brighter. Others can reject ambient light, so the image is better with any lights on.

Now, in fairness, if you have a tiny, budget projector that only puts out a handful of lumens, you won't gain much by getting a screen. There's not much performance to begin with, so there's not much to improve. Full-size budget projectors, and anything more expensive, can definitely benefit. 

If you're willing to spend a bit more, ambient-light-rejecting screens can help considerably if you want to use a projector, but also don't want to live in a cave. However, keep in mind screens can't magically make your projector look like a TV in the daytime. They also tend to add a sort of sheen to the image that isn't distracting, but it is a step back from the smooth image created on a traditional screen.

Getting into it: Important factors to consider

If we dig deeper, there's a surprising amount of physics that goes to getting an image from a tiny chip inside a projector through the air and into your eyeballs. The same projector in two different rooms could have radically different performance. Two of the biggest reasons for this are the placement of the projector, and the screen. 

As mentioned above, a decent screen is crucial to the performance of any projector. This is because all projectors need to reflect off a surface to be seen at all. That surface does a combination of reflection and absorption, both of which are key in how the image appears to you. 

In order to understand how screens work it helps to imagine three different surfaces: a thick black curtain, a mirror and a piece of white paper. Shining onto these surfaces is the light from a projector or, if it's easier to envision, the light from a flashlight. 

Firstly, a curtain will absorb most of the light coming from the projector, and the image will appear dim. The same is true, to a lesser extent, if you're using a wall instead of a screen. Even brighter shades of paint will absorb more light than a dedicated screen.

A mirror, on the other hand, reflects nearly all the light and in such a way that it's impossible to see the image. The light bouncing off it travels at a specific angle in relation to how it hits the mirror. This analogy is important for screens because most projectors have an upwards throw, so they're either mounted above the top of a screen, or placed on a stand/table below the screen. If the projection surface was a mirror, most of the light would bounce toward the floor (in the case of a ceiling mount) or the ceiling (in the case of a stand/table). This is a particular issue with ultra-short throw projectors, since the severe angle they are in relation to the screen means that without a special screen, a lot of light gets wasted on the ceiling.

Now imagine a piece of white paper which could, theoretically, reflect light evenly. This surface could combine the best properties of the previous two types by enabling you to: 1) see the image, and 2) get most of the light reflected back to you. However, in reality the paper would scatter the light too much, or at least more than what many screens do, so the image wouldn't be as bright as it could be. 

These extremes should give you an idea of what's necessary with a screen. At its simplest, a screen has to reflect the light evenly so you can see the image. Beyond that, many screens have additional special coatings that can direct or focus the light. Screens with a positive "gain" can make the image appear brighter where you're sitting, somewhat similar to how the lens of a lighthouse beacon focuses the light so boats can see it farther away. 

Ambient light-rejecting screens, commonly paired with ultra-short throw projectors, take this one step further, not only directing the light coming from a sharp angle more toward your eyes, but absorbing or redirecting light coming from different angles so the image isn't as washed out. These types of screens can add their own texture to the image, and they're often quite expensive, though they can make for a brighter image, even when there are lights on in the room.

A few companies make reflective paint, to apply directly on your wall instead of a screen. Even the smoothest of these can have visible texture, which will show up in the image. They also won't be able to focus the light as much as a higher-gain screen.

Improving brightness

If a screen isn't in your budget but you want to improve how your projector looks, there are a few things you can do to improve its brightness. They're not going to transform a dim projector into a bright one, but they'll help. 

• Size: The first, and perhaps most obvious, is to just make the image smaller. If you don't have a screen, either at all or yet, experiment with zoom or placement to make the image smaller. A small decrease in size can greatly increase how bright the image is. 
• Lamp and light source settings: Most projectors have a setting to increase lamp power to increase brightness. This, unfortunately, has some side effects. A brighter lamp won't last as long (not an issue with LED and laser-based projectors), so you'll be replacing it more often. This usually means the projector's fans will run more and at higher speeds, increasing noise in your room. Some projectors have a Dynamic lamp mode (or another feature with a similar name), which increases the lamp power for bright scenes and decreases it for dark scenes. Typically these extremes are the same as the projector in its brightest and darkest modes.
• Picture settings: We recommend settings to make your projector look its best, but usually that comes at a cost of overall light output. A less accurate mode, either a cooler "bluer" color temperature, or less accurate color mode, will either make the image actually brighter, or at least appear brighter. The cost here is a worse looking image, however.
• New lamp?: If you bought the projector used, or you've had it for a while, it's possible replacing the lamp will make the image much brighter. In the projector's menu most projectors will have a lamp hour counter that tells you roughly how old the lamp is. You can check online to see how close this is to the recommended replacement life. If you bought it used, it's possible the seller reset this counter, so be skeptical if it's a few years old with no hours on the lamp. If you've replaced a still-working lamp, save it in case something happens with the new lamp. That way you'll still have something while you wait for a new replacement. Avoid third-party or knock-off replacement lamps though, as they might be dim compared to their "real" counterparts. However, LED and laser projectors don't have lamps, and so aren't susceptible to this issue.

Beyond that, it's just about getting a brighter projector. Fortunately, we've got a few picks along those lines.

As well as covering audio and display tech, Geoff does photo tours of cool museums and locations around the world, including nuclear submarines, aircraft carriers, medieval castles, epic 10,000-mile road trips and more.

Also check out Budget Travel for Dummies, his travel book, and his bestselling sci-fi novel about city-size submarines. You can follow him on Instagram and YouTube.