A Little History
The viewing distance of LCD TVs is determined or rather preferred, through many different thoughts, opinions, variables, and some science. The best rule of thumb that is currently agreed on is that a bit too close is better than a bit too far. This is because many people prefer an immersive experience compared to an experience that does not immerse you into the program you’re viewing.
We can best thank Bernard J. Lechner for his help with finding the best TV size-to-distance relationship for optimal viewing distances. Over the years with his time at RCA he tested many televisions in homes around the country to best figure out how we as humans can process content coming from a TV’s screen. His work coined a phrase called the “Lechner distance”.
A Little Understanding
There are a couple of things that drive people when attempting to figure out the best viewing distance for a TV.
What is considered “presence” or as it is also known as “immersion”, is one of these (I guess you could say) metrics. Regardless of human limitation or the science behind the perfect distance away from the screen, if you do not feel involved, then what is the point? That is precisely what drives the foundation of a great viewing distance. Also, why a bit closer is a bit better than a bit further away.
Resolution At An Angle
In 2004 a book called the Photoshop CS3 Bible helped to explain a bit about resolution. It states that resolution is the number of pixels in a fixed linear measurement. That’s why 1920 by 1080 resolutions are named as such. It references the amount of pixels in a horizontal and vertical distance that the pixels cover. This is hugely important to remember because though the resolution increases, the quality of the image or scenes do not necessarily increase in the same way. So keep that in mind to help better understand presence. A better quality image or scene will help you to be more immersed.
Imagine placing a TV a fixed distance away from you. Then place a camera right where you are standing. Next, line up the camera’s lens with the middle of the TV’s screen. Now move the camera closer forwards and further back as you take photos of the TV. You’ll notice that some photos do not look as good as the other photos you take. This is great and will help you determine a great viewing distance for a photo to be taken. Our eyes work in a similar fashion, but with one difference. Our eyes move to look at different parts of the screen and are not always placed in front of the TV screen. This is important to remember when finding the right TV for you. It can completely destroy an experience for you or for some caught on the far right of the screen. As you move closer you fall into a worsened viewing angle. Though moving away will help this, the immersion can also be lost.
Fixed distance methods are the most common as they are the easiest to test and implement. Another set of methods is based on the size of the TV. I’ve listed some methods below.
TV Diagonal Length x 2.5: One of the most common methods used to this day. This is meant for when the display occupies ~20 degrees of your FOV. You take the diagonal length of the TV you’re viewing and multiply by 2.5. The resulting number is the distance you should be viewing the TV at. Though widely regarded as the most common many believe it is not the best as the viewing angle is quite good, the immersion may be lost.
TV Diagonal Length x 1.6: Though similar to the method listed above, this method is meant for when the display occupies a 30-degree field of view. You take the diagonal length and multiply by 1.6. The resulting number is the optimal viewing distance. This method is often referred to as the SMPTE 30 Method as it is used by the Society of Motion Picture and Television Engineers.
TV Diagonal Length x 1.2: Just like the two listed above the method is achieved in the same way. Take your TV’s diagonal length and multiply by 1.2. The resulting number is your optimal viewing distance. This is for when the TV occupies ~40 degrees of your FOV. THX popularized this method as their “best-seat-to-screen distance”.
As you may have already guessed there are tons of factors when determining the best and who is to say the best is the best? Companies as they are made to do, want to make money. Imagine a company has a new huge TV they are trying to sell, but one method says the viewing distance is not to their liking, but another is a little more in line with their interests. Which do you think they will go for? Granted this is not every case, but it gives you an idea of how come so many different methods are widespread. On the flip-side two of the largest factors that contribute to these methods are limited to either technology or limits to us as humans.
Limits of Technology
I’d prefer to keep this short so here is a quick rundown of what’s going on to impact the viewing distance from a technological stand-point. There is what is called a pixel-grid. Normally, when the TV is on it is obscured by the light on the screen and overlooked by the naked eye. By moving forward as suggested from earlier listed methods, your immersion will be kept to its max, but as you move too close, the pixel grid becomes noticeable. This will ruin the quality of the image or scene and in turn, ruin the immersive experience. Calculating the point at which humans can see the pixel-grid or inner working parts of the display is hard to determine as all humans are different.
As humans, our ability to view things at a distance is a little different for everyone, but for the most part, remains a fixed result that we can measure. This has held true over many years and is largely in thanks to Dr. Hermann Snellen for which Snellen Chart was named after. Dr. Snellen stated that one arcminute was the limit that humans begin to lose critical detail in an image or scene they are viewing. This is huge to remember as the further you place a TV away from your seat, you may lose the ability to make out small details on the screen. This, in turn, will result in a loss of an immersive experience for you as the viewer.
A little bit of feeling and a little bit of science goes a long way to finding the best distance for your viewing experience. Remember though that they are not directly linked and are subject to change. You need to experiment to find what works best for you. In 1997 a study, that you can find here, proposed that increases in the size of the screen would give a better feeling of immersion while not necessarily changing the distance it was viewed at. They also hypothesized that the content was hugely important as well regardless of the distance the TV was view at. Think of these factors and try it all out for yourself.