More on displays

Myth #3: A viewer should sit no closer than 1.5 times the diagonal width of a HDTV.

Fact: It’s complicated.

What happens with you sit too close to the TV? You start to see pixels rather than the big picture. Somewhere along the line, consumer electronics retailers began talking about buying a TV so that you are sitting somewhere between 1.5 to 2.5 times the diagonal width of the TV. This is as reasonable as saying that diamonds should always be two to three months salary.

Take my 30” LCD monitor. Using this guideline, should I be ~4 feet away from my computer? No. That’s because the pixel pitch, the size of each pixel, of my 30” monitor is similar to many other LCD monitors – there’s just more surface area. It all boils down to dot pitch/pixel density/screen door effect/fill factor. It’s a question of how much empty space is in between each pixel. Today’s LCD panels do an exceptional job of keeping pixel pitch narrower. In other words, you can be much closer to an LCD flat panel before you begin to see individual pixels. Plasma tends to have a larger pixel pitch (bad) compared to LCD. That’s because plasma cells that are too small can end up being too dim.

When it comes to projection technology (both rear projection and front projection), LCOS technology such as Sony SXRD and JVC D-ILA offers near perfect pixel pitch (because the control ICs are behind the reflective surface), followed by DLP (the control circuit is along on edge of the mirror), followed by conventional LCD. Remember, the control circuitry for an LCD projector and a LCD flat panel can be very similar – but the LCD projector has to fit 1920x1080 pixels into a 0.74-inch device.

Bigger is better -- that’s why watching Hollywood blockbusters remastered onto IMAX is an awesome experience. With today’s 8th generation 1080p LCD and plasma technology, and current generation SXRD and D-ILA technology, you can get up much closer to screen than you could ever before.

Both THX and the Society of Motion Picture and Television Engineers (SMPTE) have established guidelines for setting up movie theaters with the optimal screen size and seat distance. SMPTE standard EG-18-1994 recommended a minimum viewing angle of 30 degrees for movie theaters, while the THX TAP program recommends that the back row of seats have a 36 degree viewing angle, and no worse than a 26 degree or greater viewing angle if the theater still wishes to maintain THX certification. Of course, sitting in the “sweet spot” middle of the theater ends up bringing your angle of view wider. How does this translate?

TV Size	Maximum distance screen to maintain THX 26 degree specification	Maximum distance recommended by SMPTE 30 degree specification	Recommended THX distance to the "back of the theater” (36 degree specification)
32"	5 feet	4.3 feet	3.6 feet
40"	6.3 feet	5.4 feet	4.5 feet
46"	7.2 feet	6.2 feet	5.1 feet
60"	9.4 feet	8.1 feet	6.7 feet
70"	11 feet	9.5 feet	7.8 feet
100"	15.7 feet	13.6 feet	11.2 feet

This range of distances is right in the sweet spot of where the full benefit of 1080p displays can be seen. However, for many TVs, sitting at THX recommended distances results in the ability to see the individual pixels.

If you want to bring the full movie theater experience home, you’ll need to go big. At these viewing distances, the benefits of 1080p are noticeable. In addition, the video processing in 1080p televisions with inverse telecine tends to be better. Bottom line?

FiringSquad Recommendation #2: if you can afford it, go with a 1080p LCD or plasma flat panel or a 1080p SXRD or DILA front projector. That’ll get you the best picture quality both as a result of the increased resolution and more optimal video processing.