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.
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).
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.
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.
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.