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About the Optimum Viewing Distance of Passive 3D Monitors

February 25th, 2013 · 5 Comments · GeForce 3D Vision

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There has been a lot of information what works best and various different recommendations what are the optimum viewing positions of passive 3D monitors, but still a lot of people are having hard time properly adjusting these displays for best stereoscopic 3D experience. There is also a lot of controversy going on around the half vertical resolution you get in stereo 3D mode and the end visual results you get. But with all the recommendations and suggestion what works and what not I ended up doing some testing of my own and decided to present what works best for me when viewing a passive 3D monitor and share this information so it might help others as well. I’ll be using a 23-inch FPR 3D monitor to illustrate this example and that monitor is the Philips 236G3DHSB that I’ve recently reviewed here on the blog. What you should be well aware of is that passive 3D monitors have a very narrow vertical viewing angle when in stereoscopic 3D mode, this angle is usually 5 to 7 degrees up and down, so a total of 10-14 degrees total. Also that when 3D mode is active you get half of the vertical number of lines composing what each eye sees from the total resolution of the display, hence the half vertical resolution of the display. The fact that the the perceived sharpness of the image displayed with half horizontal resolution per eye on a passive 3D display might look better than on a full resolution per eye active 3D display when using Full HD monitors does not necessary mean that both solutions offer the same display resolution in stereoscopic 3D mode. There are many factors that affect how we perceive sharpness of display resolution, but now we are not going to debate these here.

Let us start with a quick look on what various manufacturers of passive 3D (FPR 3D) monitors are recommending as optimum viewing angles and distance for achieving the best experience when using their products in stereo 3D mode. All of the information below is taken form the user manuals of various 23-inch Full HD passive 3D monitors, these are models that the manufacturers decided to publish such information as some manuals do not contain any recommendations at all.

AOC e2352Phz
Sit at a position at least 70 mm (they made a mistake and probably meant 70 cm, not mm!) away from the display unit. Keep the line of sight horizontal to the display unit as far as possible (with the upper and lower angle of view within 10 degrees).

HP 2311gt
For optimal 3D viewing, you should be approximately 60 to 70 centimeters (24 to 28 inches) from the computer display. Depending on the viewing angle, the operational distance from the display can vary.

LG D2342P
The optimal viewing angle of the monitor is 12° in vertical direction while 80° in horizontal direction; the optimal viewing distance is between 50 cm to 90 cm from the monitor. When you view 3D images outside the optimal viewing angle or viewing distance, the images may look overlapped or not be displayed properly in 3D.

Philips 236G3DHSB
For an optimal 3D viewing experience, we recommend that you: Sit at a distance that is at least 55cm; Watch the monitor away from direct sunlight as it may interfere with the 3D experience.

There are no surprises about the viewing angles at all here, we already know they are quite limited and this limit is not affected by the LCD panel type used in the monitor, even an IPS panel won’t help, the limit is caused by the polarizing filter applied over the LCD panel that separates the left and right eye images for stereoscopic 3D use. As for the minimum recommended distance from the 3D monitor we see different numbers from 50 centimeters to 70 centimeters (about 20-28 inches) and as for the maximum recommended distance only LG recommends up to 90 centimeters (about 35 inches). So what works best for me, neither of these recommendations are actually good for me…

A person with normal vision not wearing glasses or wearing the right diopter glasses to correct his vision achieving the same level as what is considered as normal vision would need to sit at about 90-95 centimeters away from a 23-inch passive 3D display (about 35-37 inches) or about 1.5 times the diagonal of the monitor. This minimum distance is required in order for the viewer not to be bothered by the increased distance between the vertical lines that build the image for each eye for stereo 3D content. If your vision is nt good enough to be considered “normal vision” and you wear prescription glasses with 1 diopter you might be able to reduce that minimum comfortable distance to about 75 centimeters (about 30 inches) if you are not wearing your glasses in order not to be bothered by the lines.

Moving up to about just 55 centimeters away from the 23-inch passive 3D displays you will find that this is a the about absolute minimum at which you can get into the correct vertical viewing angle limit and be able to properly perceive volume, but at that distance you will be bothered by the vertical lines building the image you will see. So manufacturers may be right that this is about the recommended minimum, but it is more like the absolute minimum distance and not the most comfortable. Actually the farther you are from the monitor the easier it is to get into the very narrow vertical angle for best results when using the display in stereo 3D mode, but there is a limit to that as well. Going to further away from the monitor will lead to the 3D image starting to look flat thus loosing the stereoscopic 3D effect and the sense of realism provided by the displayed 3D image will further diminish because of the very low FOV coverage your vision will have. Going past about 150 centimeters (about 60 inches) you will start to loose the perception of volume and the image on the screen will start to look flat, not to mention that the immersion factor won’t be that good either because of the screen covering a small part of the vision, but at least it is much easier to get in the vertical viewing angle (at the cost of the reduced perception of sharpness and thus resolution).

The optimal viewing distance of a 23-inch passive 3D monitor for me personally is around 90-100 centimeters (about 35-40 inches), a distance at which I’m not bothered with the vertical lines and the image I perceive is still sharp. At that distance the stereoscopic 3D effect (the sense of volume) is still quite good for various 3D content, and the only drawback that remains is that the feeling of immersion is not that good due to smaller part of the vision covered by the display. And at that distance from the display it is easier to stay withing the optimal vertical viewing angle when you’ve setup the display correctly even with some normal head movements. As a reference to use for a comparison I usually use a 27-inch active 3D monitor in stereoscopic 3D mode at a distance of about 60-70 centimeters for optimal sense of immersion.

If you are using a passive 3D monitor feel welcome to share what works best for you in terms of optimum viewing distance in the comments below.


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5 responses so far ↓

  • 1 Max // Feb 26, 2013 at 09:54

    Yes, i also use my LG D2342P from 50-100cm,
    but thats not true at least by me:

    “When you view 3D images outside the optimal viewing angle or viewing distance, the images may look overlapped ”

    I get ghosting even when i sit in the optimal viewing angle.
    I cannot find the right position from where every part of the display is ghostless. If its ok at the top, then i see double images at bottom corner. If its ok at bottom, i see ghosting above.
    You don’t have this weakness?

  • 2 Bloody // Feb 26, 2013 at 16:42

    Passive 3D monitors also suffer from ghosting/crosstalk issues, so even if you are within the optimal vertical viewing angle you may still see some crosstalk, this vary based on the content being displayed as well. Have you tried moving even further back from the display to see if the crosstalk you see gets less or not?

  • 3 JørnL // Feb 27, 2013 at 02:08

    Viewing 3D on a small passive monitor is always a compromise between several conflicting issues:

    1. You need to stay within the monitor’s 3D zone to avoid ghosting.
    2. Longer distance minimizes visibility of stripes, typically 1,5 times monitor’s diagonal.
    3. Short viewing distance gives wide field of view and good immersion.
    4. A small screen gives less depth and roundness compared to a larger monitor at same FOV, but longer viewing distance increases depth and roundness (at the expense of immersion).

    With a monitor for active glasses (or anaglyph), there are two issues less; avoiding visibility of stripes and staying in the 3D zone. For games where you can increase depth values, you can have both full immersion and depth. But with a Blu-ray 3D, you can not increase depth, so you are back to the choice of immersion or depth/roundness.

    Of the four issues listed above, the first one is the most critical for passive 3D monitors. If you are outside the 3D zone and get extreme ghosting, the monitor is quite useless. The vertical 3D zone is limited by a near point and a far point. At the far point the viewing angle is always 0 degrees. The vertical viewing angle gets wider, the closer you get to the near limit, which is opposite of the illustration in the article above.

    The correct 3D zone is never given by manufacturers, so far (although HP comes close with 2311gt), but you can easily test near limit and far limit with your own monitor.

    @ Max
    I have tested the 3D zone of a LG DM2350D which I believe has the same panel as yours. I found near and far limits at respectively 48 and 85 cm. You can check your own monitor using the test described in my second comment here:
    http://3dvision-blog.com/8648-review-of-the-philips-236g3dhsb-passive-3d-monitor/#comments

    Note that LG D2342P does not use RealD type glasses, so you should use original LG glasses that say “Monitor” on the temples. If you do the suggested test and still do not find any positions without ghosting, you may have a monitor where the FPR filter is slightly rotated.

    @ Bloody
    I hope you can include testing of near and far points in future tests of passive 3D monitors, as well as RealD glasses compatibility. The test takes less than five minutes and is to me one of the most basic specifications of such a monitor. For instance buying an Asus VG23AH with far point at 65 cm does not work well for someone who prefers to sit 100 cm away from the screen. Knowing the far limit is useful both when choosing a monitor or when using one.

    Also RealD glasses compatibility is useful to know, since all high end passive glasses use the RealD standard. Most passive monitors so far do not use the RealD standard.

  • 4 Max // Feb 27, 2013 at 13:59

    JørnL:
    Of course i use the bundled white “monitor” glasses, that’s not the problem.
    I watched the rabbit test: white is 100% good, at grey rabbit is slightly visible and worse at black test.
    In black test i also see more ghosting at bottom right 5x5cm corner, when i change my viewing angle, it will be better, but worse at top 5cm row. Is this normal?

  • 5 JørnL // Feb 27, 2013 at 19:48

    Max:
    Are you talking about the black test that is a part of the rabbit test? Or do you mean the test with full black for one eye and full white for the other, as suggested?

    What you see would be quite normal if viewing full black/full white test and distance is about 80 cm or more.

    If you are at the centre line of the monitor, what do you see at which distances?

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