Choosing your video projector

Note : This page has been translated into English from French by a machine translation tool

You are a professional and need a video projector for your meetings ? Or would you like to spice up your movie nights at home by getting a much bigger screen for the budget of a TV set ? But for that you need a few things to make your choice and better understand the characteristics of these devices … You’ve come to the right place. Let’s take a look at the main features…

If you have already had the opportunity to inquire about the acquisition of a television, you will see that we will naturally find identical technical comparison elements here. And this is quite normal since the purpose of these two types of devices is quite identical, namely to display a picture. Let’s start with the first one that you certainly know, the resolution of the image.

The maximum resolution

Image resolution is the number of pixels, or dots, that make up the image (see our article DTP for more information on raster images composed of pixels). Obviously, the higher the resolution, the more precise and detailed your image will be. Among the best known are DVD resolution (480p), HD (720p), Full HD (1080p) and, in recent years, 4K (2160p). We even see on the market this year TVs with 8K (4320p) resolution, whose upscaling, the conversion of your image from lower resolutions to 8K, which is essential because native 8K sources are still very rare, is managed by artificial intelligence (see our article Artificial intelligence for more information). Unfortunately, prices are still quite inaccessible for the common man, like the Samsung QE98Q950R (see the product page on the Samsung website). But let’s come back to our subject…

We are not going to focus on this last image resolution, which is still too marginal, to concentrate on the most common resolutions currently in use, namely Full HD (1080p) and Ultra HD 4K (2160p). You will only find here in brackets the number of distinct vertical lines that make up your image because the number of horizontal lines, i.e. those that represent the width of your image, depends on the format of the latter. As an example, the most common being 16:9, this generally gives us an overall resolution of 1920x1080p for Full HD and 3840x2160p for Ultra HD 4K.

Entry-level portable projectors today offer 480p resolution called WVGA. The only positive points of these devices are their weight and size. They can be carried in a bag, allowing you to take a projection tool everywhere. Unfortunately these resolutions are too low to offer images of a pleasant quality and can only be suitable for this precise need of transportability. They can nevertheless be sufficient to project a slideshow to a small audience but often find themselves confronted with another problem which is their low brightness which we will see in the next point.

If you don’t need this portability, you can easily find video projectors in a more classic format like those found in most meeting rooms. Many of them offer Full HD (1080p) resolution at the lowest prices. We therefore invite you to choose at least this resolution in order to project with a good level of fidelity your illustrated presentations or even your movies for personal use. If you can afford it, choosing a device that supports Ultra HD 4K resolution remains the ideal choice and will allow you to project the most faithful native content. However, this resolution is more suitable for moviegoers who want to get the most out of 4K video available online or the 4K Blu-ray Disc (see our Optical media article for more information) that’s widely available in stores today.

Brightness and lamp

Now let’s look at the second aspect to consider when buying a projector: its brightness. Finally, more precisely the brightness of its lamp. It is this, generally expressed in ANSI lumens, and we insist on the need for the presence of ANSI in the lamp brightness data provided by the manufacturer, which will allow the best possible contrast (which we will see in the next point) and make the image pleasant even in conditions where the ambient light is strong.

You have probably already realized how difficult it is to distinguish an image, especially one that is predominantly dark, on a bright, sunny day in an extremely bright room. And the closer your TV is to a window, for example, the duller the picture becomes. This is a concern that you will obviously never have in the evening, once the sun has gone down, with all the lights out in your living room. It is the same with your smartphone if you are not in automatic adjustment of the brightness of your screen. In minimum brightness, you’re comfortable reading an article or checking your Facebook news feed in the dark of your room, but you won’t see anything on your screen on a sunny day outdoors. All this to say that brightness is important because if you want to use your projector in a meeting room in broad daylight without the ability to dim the light coming from outside, only the power of the lamp will allow you to make your presentation visible to your audience.

So what light output should you choose ? It is difficult to answer this question very precisely because it is of course partially subjective but above all strongly dependent on your use and your environment. However, generally speaking, choose a video projector with a minimum luminosity of 3000 ANSI Lumens if you want to be able to project in unfavorable lighting conditions, i.e. illuminated in broad daylight by outside light. On the other hand, a brightness of around 1,000 to 1,500 ANSI lumens can give you complete satisfaction, but on the sole condition that you use the projector in conditions of darkness or even near complete darkness, which are more common when watching a movie in the evening, for example.

Now let’s see what are the different types of lamps you can find in our expensive fixtures ?

The UHP mercury lamp

The lamp is the element that produces this brightness. The most common type is the mercury lamp. The latter has advantages and disadvantages. Among them, the cost correlated to the ecological footprint. These lamps are relatively expensive and must be replaced relatively regularly for a slightly intense use. Their lifetime is between 3500 and 7000 hours depending on your use. Indeed, most of the time, you benefit from an ECO Mode which will allow you to save the lamp but will not be adapted for use in a lit room. Otherwise you will be at the bottom of the range of its lifetime. Without counting on a significant loss of performance over time, that is to say that its brightness will be lower and lower the closer you get to the end of its life. You will also have to wait a little while when you turn on your device before you get the optimal brightness because they require a warm-up time. On the other hand, as you will have understood, the advantage is that these lamps can be replaced and offer a good level of luminosity when they are at the beginning of their life. Most of the time it is thanks to them that you can afford a device at a lower cost.

The LED Lamp

Secondly, there are LED lamps that are much less energy consuming than UHP mercury lamps and have a much longer life. The life expectancy of this type of lamp is usually between 20,000 and 30,000 hours of use. On the other hand, they are mainly used on small projectors, the famous picoprojectors, because of their lack of brightness, which does not make them suitable for all uses as we have seen previously.

The laser

Finally, we find a type of lighting that has recently appeared on the market and is now offered by the largest manufacturers of video projectors, the laser. It is now a high-end technology. Indeed, it can achieve brightness even higher than mercury lamps while offering the life of a LED lamp, between 20,000 and 30,000 hours of use. It generally allows you to dispense with a cooling fan and thus reduce the noise emission level of the device but also to maintain the optimal lighting power much longer and it does not require the same warm-up time each time you start your device. Thanks to the laser, the device can in fact operate almost instantaneously with optimal lighting conditions. On the other hand, this technology is a little more expensive and is therefore reserved for higher-end devices, whose prices are often above €1,000. It is obviously to be preferred if you want a device for intensive use, that you will place in a place that is difficult to access or if you want to take advantage of sufficient lighting power to project with optimal rendering in a place that may be significantly affected by outdoor lighting.

The contrast ratio

The contrast ratio is also one of the elements to take into account when you want to purchase a video projector. Indeed, as previously mentioned, the contrast ratio is the element that determines the color depth of an image. It corresponds to the scale of variation between the lightest and darkest areas of an image. You may have already been confronted while watching a movie, when watching scenes shot in dimly lit locations, with particularly dark areas in the image where you could not distinguish details. This is a direct consequence of insufficient contrast, the screen capacity in this case does not allow for the reproduction of the differences in tones in the dark areas. Of course, the same can happen in areas that are too bright. An image with low contrast appears dull. If you can, and especially if you plan to use your projector for video and film projection, use a high contrast level.

So what is high contrast ? The answer to this question is not, once again, all white or all black… Indeed, you must already take into account the fact that in the data sheets you will find two contrast values: native contrast and dynamic contrast. And if you take a closer look at the data sheets you will see that you rarely have both. So the risk is that you will only have technical data that are not comparable. Indeed, the dynamic contrast is really only an artifice. It is an iris that, by opening more or less, regulates the brightness of your image to optimize the contrast rendering typically by lowering the brightness on dark images and conversely by increasing it on light images. So how do you make the difference ? Answer : With numbers… Indeed, a contrast of 100,000:1 is not a native contrast on a consumer projector and it is the latter that is by far the most important. Since you’re going to want numbers, a native contrast between 2000 and 4000:1 is a very correct contrast for a use that can go as far as the cinema. So don’t take into account the totally delirious values that you can see in technical data sheets, which can go up to 2,500,000:1 ! Yes, we have already seen it ! It has become a marketing argument and it is better to rely on tests and trust more reasonable contrast values.

But the perceived contrast of your image will unfortunately not only depend on the performance of your device but also, as we discussed in the previous point, on the brightness of the diffusion environment. It is obvious that if you have the sun’s rays hitting directly the projection area of your image, your contrast will be severely degraded. Fatally, you can also deduce that the luminosity of your lamp or the lighting system of your video projector will also have a consequence on the contrast of your image. We haven’t mentioned it, but the reflection quality of the surface on which you project your image will also affect the way it looks. Morality, favour the choice of a screen and a balanced configuration between the different characteristics.

Image size and projection distance

Then we have the maximum image size your device can deliver, the distance from the screen and the projection ratio. All these data are a little bit related because the third is the ratio of the second to the first. Thus we have :

Projection Ratio = Projection Distance / Image Size

Fortunately, the flexibility of a video projector comes from the fact that most of the time the projection ratio is adjustable, a bit like a camera zoom. Adjusting the lenses will allow you to increase or decrease the size of the projected image without having to move the camera. Needless to say that the comparison with a camera zoom stops there because the adjustment latitude when possible is generally between 1.1 and 1.6x, which means that the minimum ratio is multiplied between 1.1 and 1.6x to reach the maximum ratio. The second level of flexibility, when one can act on it, is in the distance at which one places the camera from the projection surface. We can therefore move it backwards to enlarge or bring it closer to reduce the size of the image. The projection ratio or the range of ratios allowed by your camera depends on its focal length, again like a camera lens. There are three types: short, classic and long focal lengths. And your choice will be made according to a main criterion … the configuration of the place.

Let’s take an example… You can’t place your device far from the projection area but you need a large image because the farthest members of your audience will be away from the screen. You will then choose a short focal length, i.e. with ratios less than 1, in order to have the largest possible image with a device as close as possible to the screen. They are however not the most common on the market but some are even configured to have ultra short focal lengths (with ratios less than 0.2) like the Dell S718QL. These devices are then placed directly at the foot of the screen and are a superb alternative to a TV screen. In case you have the possibility to move your camera backwards and where your needs in terms of image size would be limited, you can turn to cameras with long focal lengths, i.e. generally with ratios of 2 and above. The focal lengths that fall between these two terminals will be the easiest to find because the majority of video projectors are equipped with standard focal lengths with projection ratios between 1 and 2.

As mentioned earlier, we will return to the need for a homogeneous whole. Indeed, the more your device will be far from the screen the more you will have to attach importance to the brightness of its lamp. The distance influences negatively the rendering of the image since the more you move away from the source the more it loses in intensity, and this until affecting the contrast in the case which concerns us. Finally, do not forget to take into account the native resolution of the image. You have probably noticed that the closer you get to a television screen, the more you see the defects of the image and, incidentally, the pixels. If you magnify the line deliberately, this falls under the sense that a screen of 7 meters diagonal with a HD resolution (720p) will certainly not be very pleasant to watch at less than 4 meters. It is therefore necessary if you need to move your device away and thus enlarge your screen to orient yourself at least towards Full HD (1080p). For very large diagonals (more than 5 meters), in order to ensure visual comfort for you and your entire audience, choose the Ultra HD 4K (2160p) if your budget allows it.

Connections

We are going to end this section dedicated to video projectors with the connections. Connections are what will allow you to use your projector in an optimal way in a maximum of circumstances and to make it compatible with the equipment you already own.

Let’s take stock of what we think is essential to find on a video projector…

HDMI ports

Just like what you can look for on a TV, two or even three HDMI inputs can come in handy so you don’t have to unplug and plug your devices in and out all the time. Here again, it’s your use that will dictate your choice, but today it’s the main means of broadcasting the image from a computer, Blu-Ray player, home theater amplifier, tablet or smartphone. Don’t forget to check their compatibility. If at least one of them is in HDMI 2.0 version, it will only be better for the future of your device. Finally, their compatibility with technologies such as MHL used to broadcast content from mobile devices can be a plus.

USB ports

One or even two USB inputs can come in handy to allow you to play your media and presentations directly from a USB stick or hard drive. However, be sure to ask about the file formats that the device supports if this is not an option for you. You can start your search by visiting manufacturers’ websites or trying to find manuals in electronic format, for example. Don’t forget that just because there is a USB input does not mean that your device will be able to read all the content you provide. If at least one of them is equipped with a recharging function it’s a plus, when using a Fire TV Stick for example.

Audio output

Whether it is a 3.5 mm analog audio output, an RCA output or, in an effort to optimize signal quality, an S/PDIF digital output, it is preferable to ensure that you can extract the sound from your device in order to broadcast it in a quality that can range from correct to excellent depending on the audio system chosen and your level of requirements. We therefore advise you to ensure that at least one of these connectors is on the back of your device.

VGA input

Even if VGA connections may seem a bit outdated today, it can in some cases be very useful so that you don’t find yourself unable to broadcast the image of a computer equipped with a graphics card old enough not to have an HDMI output. Make sure that you also have an audio input in this case, so that you can directly enjoy the audio system that may be connected to the projector for your audio broadcasts. Otherwise, you’ll have to make up for the soundtrack since the VGA cable is only dedicated to transmitting a video signal.

A more recent feature, a video projector can also be equipped with a network connection or even a wireless network connection (Wi-fi). The advantage in both cases is that you no longer need to connect the computer or tablet that will serve as the source of the video projector. You will only need to make sure to connect your projector to your personal or corporate internet network. All you need to do is connect the device that will serve as the broadcast source to this network and thus, via Airplay or an add-on module, display your content directly. Regarding these features, you will find devices equipped with Ethernet network connectivity to connect you by wire and others for which you will only have Wi-Fi functionality, either originally or via the addition of a USB dongle. In the latter case, simply purchase the wireless network receiver add-on and connect it to one of the USB ports on your projector to add this functionality. This is therefore an element to take into account in the number of available USB ports if you wish to benefit from this function.

You now have almost all the cards in hand to make your choice in an informed manner. For more information on the elements of a video projector’s technical specifications that you may need to take into account when making your purchase, we recommend that you consult our article Other characteristics of a video projector.