Viewing angle: Based on the inputs, this is the viewing angle or arc for your set up.
Maximum recommended viewing distance: Suggests a viewing distance of three to six screen widths for video. This corresponds to the point at which most people will begin having trouble picking out details and reading the screen. Probably too far away to be effective for home theater, OK for everyday TV viewing. Most people are comfortable watching TV between this distance and half this distance.
Maximum SMPTE recommended viewing distance: SMPTE standard EG-18-1994 recommends a minimum viewing angle of 30 degrees for movie theaters. This seems to be becoming a de facto standard for front projection home theaters also. Viewing from this distance or closer will result in a more immersive experience, and also lessen eye strain caused by watching a smaller image in a dark room.
Maximum and Recommended THX viewing distances: THX also publishes standards for movie theaters to adhere to for THX certification. THX requires that the back row of seats in a theater have at least a 26 degree viewing angle and recommends a 36 degree viewing angle.
SMPTE and THX screen widths: Based on the viewing distance supplied to the calculator, these are the minimum screen widths required to meet the SMPTE and THX recommendations discussed above.
Viewing Distances based on Visual Perception: These distances are calculated based on the resolving power of the human eye, or visual perception. The human eye with 20/20 vision can detect or resolve details as small as 1/60th of a degree of arc. These distances represent the point beyond which some of the detail in the picture is no longer able to be resolved and "blends" with adjacent detail.