[FDArchitects]

The horizontal viewing angle also called the field of view is the angle subtended by from each corner of the cinema screen to the center of the seating position. 
There are two main standards 

1. SMPTE (The Society of Motion Picture and Television Engineers )  specifications 
   
2. THX  (founded in 1983 by George Lucas) specifications 
   

Horizontal viewing angle 


The horizontal angle to a flat projection sheet at which distortion on the screen becomes substantially intolerable is 60 degree measured to the far side of the projected image . Curvature introduced into the screen may render the distortion less from the extreme seats on the opposite side of the center line of the house but will increase distortion from the seats on the same side of the center line



Taken from Time-Saver Standards for Building Types by Joseph De Chiara, Michael J. Crosbie



THX specifications : 
THX specifications have a minimum viewing angle of 36 degrees from the last row of seats. The viewing angle ‘sweet spot’ seems to be around 45-50 degrees and back row of seats in a theater have at least a 26 degree viewing angle.  

SMPTE standard

SMPTE standard EG-18-1994 recommends a minimum viewing angle of 30 degrees for movie theaters
SMPTE specification have maximum 61.8 degree viewing angle for closest and 33.3 degree for farthest and 43.4 degree is reference of SMPTE for 2.39 : 1 image 



Vertical viewing angle 
The vertical angle of 30 degree  at the spectator's position establishes the distance from the closest seat to the screen or to the highest significant object on the stage.
 
The highest seat in the balcony must be on a line which is not more than 30" to the horizontal at the front curtain at the stage floor if it is not to be above the limit of reasonable distortion .

Taken from Time-Saver Standards for Building Types by Joseph De Chiara, Michael J. Crosbie

THX specifications : 
The vertical viewing angle is measured at seated eye height from the front row center seat to the top of the tallest projected image. The THX specifications have no references to a "best" or "optimal" vertical viewing angle.  However, normal human vision's optimal cone of vision has a radius of approximately 15 degrees.  No viewer to have an angle of greater than 15 degrees to the top or bottom of the screen. Typically this puts viewers eye’s at 1/3rd to 1/6th of screen height.


SMPTE standard EG-18-1994 notes that: 

"for most viewers physical discomfort begins when this angle exceeds 35 degrees. We strongly recommend that the layout of the auditorium adheres to this engineering guideline." 
This guideline would be difficult to exceed in a home theater, with most vertical viewing angles in the 15-20 degree range. 




Vertical Viewing Field of the Eye
Vertical viewing angle at the first row preferably about 25 degrees


horizontal Viewing Field of the Eye
Horizontal viewing angle at the first row preferably about 35 degrees






Taken from Readability in Classrooms by Piet van der Zanden



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