Angle of view camera–subject distance to preserve the size of a subject, changing the angle of view can indirectly distort perspective, changing the apparent relative size of the subject and foreground. If the subject image size remains the same, then at any given aperture all lenses, wide angle and long lenses, will give the same depth of field. An example of how lens choice affects angle of view. This table shows the diagonal, horizontal, and vertical angles of view, in degrees, for lenses producing rectilinear images, when used with 36 mm × 24 mm format (that is, 135 film or full-frame 35mm digital
Inscribed angle the case where the measure of the inscribed angle is the "difference" between two inscribed angles as discussed in the first part of this proof. Given a circle whose center is point "O", choose three points "V", "C", and "D" on the circle. Draw lines "VC" and "VD": angle "DVC" is an inscribed angle. Now draw line "VO" and extend it past point "O" so that it intersects the circle at point "E". Angle "DVC" subtends arc "DC" on the circle. Suppose this arc does not include point "E" within it. Point "E" is diametrically opposite to point "V". Angles