There are a few measurements where the male average is proportionately much larger than the female average, notably glabella subtense
(GLS, around 150-200%, depending on series), supraorbital subtense
(SOS, around 120-170%), and the dimensions of the mastoid process (MDB and MDH, around 110-150%).
Angular magnification is achieved by telescopes or binoculars and increases the angle of subtense
of the image at the eye.
The variables used are Frontal Chord (FRC), Frontal Subtense
(FRS) and Bistephanic Breadth (STB) as defined by Howells (1973).
[pi] Solid angular subtense
of source modified for the effect of the observer in relation to the source (sr)
in which [theta] is the lead (or oncoming) vehicle's instantaneous angular subtense
and d[theta]/dt is its instantaneous rate of increase of angular subtense
Directions were measured by precise optical instruments Zeiss Theo 010A, and distances were measured by parallactic method with 2 m subtense
When constant velocity was simulated, the circle's angular subtense
was varied through time according to the following expression (Regan and Hamstra, 1993):
The card contained rows of numbers and figures that progressed from a larger angular subtense
(size) at the top to a smaller angular subtense
at the bottom.
When two candles of equal physical size were so perceived (even when one was twice the distance of the other), he substituted a smaller one of equal visual subtense
for the far one, with no change in perceived size (see Fig.
For example, patients quite often report seeing ring haloes around bright spotlights in a darkened consulting room, usually of between 4[degrees] and 6[degrees] in in angular subtense
, due to diffraction by the crystalline lens fibres and the pupil margin.
The angular subtense
of the lights was equivalent to that of a 200-mm traffic signal lantern at a distance of 100 m (2 mrad or 6.9 arcmin).
Figure 5 (fine line) shows the contrast sensitivity function for sine-wave gratings of equivalent subtense
. The similarity in spatial frequency tuning suggests that images are uncomfortable when they have an excess of contrast energy at those spatial frequencies to which the visual system is generally most sensitive.