The Rule Of Thumb For Direct-View LED Viewing Distances Is All Over The Place

September 29, 2017 by Dave Haynes

So what is the real rule of thumb for viewing distances for direct view, fine pitch indoor LED displays?

I thought it was 10 feet for every 1.0mm pitch, 15 for 1.5mm, 20 for 2.0mm and so on, and have certainly seen that used.

But …

Christie’s rule of thumb is 8 – meaning you multiply the pitch by 8 to get feet. So a 2mm display looks good starting at 16 feet back

However LG, which like most big display companies has introduced direct view LEDs, has an infographic out saying the rule thumb is not 10 feet per millimeter, but 3.5 feet per. So in its formula a 2.0mm display looks good from 7 feet away.

Absen says it is 1mm to 1 meter, so that 2mm would look good from 6 or 7 feet away, too.

This Dutch reseller says the rule of thumb is 1.5 x the pixel pitch, in meters. So in a 2mm pixel pitch screen it is 3 meters, or about 10 feet.

PixelFLEX says it is roughly 3 feet per 1mm. This is their chart:

NanoLumens has a chart that suggest it is about 4 feet per mm, so that the suggested distance for a 2.5mm is 10-12 feet.

Mightily confused.

I suppose it depends a bit on what you think is OK, but when you can see the individual LEDs, that tends to mean you’re inside the minimum viewing distance. I’ve seen fine pitch stuff up close and it looks OK, but just OK.

Clarity needed … opinions and definitive information (if it exists) much welcomed.

  1. Doug Wack says:

    Wouldn’t it be great if the manufacturers and AVIXA got together and created a set of LED standards? This is only a single dimension of the many that need to be understood and standardized in the world of LED.

  2. Patrick Bailey says:

    The only objective measurement is retina viewing distance. The retina viewing distance of direct view LED displays ends up very close to 10ft. per 1mm of pixel pitch. Therefore, a viewer with 20/20 vision should not be able to see an individual pixel on a 1.2mm pitch display at a distance of 12ft. or greater. However, these displays can still look very good at closer distances. I often advise that 1/2 of the retina distance still looks very good, but this is also very subjective. The only objective distance is the retina distance, or 10ft per 1mm of pitch.

  3. George Ray says:

    Patrick Bailey is accurate.

    Here are the maths-

    Standard visual acuity (20/20) in the US or 6/6 in EU is the ability to discern two points separated by one arc minute. About 300 pixels per inch at 25 cm. (The ‘Retina’ display marketing)

    This translates to 12 pixels/mm at 250 mm distance.

    A little multiplication and we get 0.6 pixels per mm at 5 meters. This is 1.6mm pixel pitch.

    The authors comment about multiply by 10 to get viewing in feet is about right- 5 meters is 16 feet.

    The Christie formula is a little closer- 12.8 feet, but the formula is based on 20/20 vision. As the population ages, the visual acuity drops, so the difference can be blamed on biology. The European scale would give the viewer a 6/7.5 visual score- still not far from normal.

    Thanks for the thought exercise.

  4. Eric Seigler says:

    Viewing distance is a subjective concept that has evolved as the industry has become more in tune with the fundamental differences between indoor and outdoor LED. There are too many factors involved that can directly affect perceived resolution such as content, size of the display and viewing angles. While three feet is the rule of thumb we walk around with, give me some highly granular content and I can make a 2.5 look pixelated from 7 feet away. It’s truly a conversation and not a hard and fast rule. I would argue there are just too many factors involved for someone to put something firm down as rule of law.

    Too often clients are misled by manufacturers into believing they need the latest resolution available even when a lower resolution will suffice. Whether that is a manufacturer simply wanting to sell the higher priced solution is up for debate but it seems that time and time again clients that are enamored by resolution have been led there under poor assumptions or worse false pretenses. The resolution needed should be a discussion not a hard and fast rule and it would behoove the industry to approach the topic with questions instead of statements. Perhaps then the client would feel they actually have input in their solution rather than being told what they “need.”

  5. Christopher Gillespie says:

    Good stuff here, but in the end, there is no answer. visual acuity and type of content mean that there are multiple answers based on what you are showing and who is watching. just like with projectors we had different rules based on text or video content.

    What i have found to be the best across the board as a general rule of thumb is the 10’/10mm. while certain installs may call for different guidelines, this is the best (and easiest to remember) rule of thumb. And yes, i know i am 4 years late to the party!

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