The Cobb method has been used since 1948 to measure the magnitude of the angle on the PA erect image
(9,10,21,24,29) The Cobb angle is found by first locating the endplates of the most angulated inferior and superior vertebrae of the curve.
A roof prism splits the light cone from an objective lens into two separate pathways, involving different internal reflections, before recombining them into an erect image
The erect image
on the 14" screen of the MC-14 is distortion free edge-to-edge because of the use of high-quality telecentric optics.
Nakedeye green flashes are most often seen when an inferior mirage of the Sun's green upper fringe merges with the normal erect image
, producing an elongated lenticular blob.
The compact, straight-through 8x21 finderscope, held securely with a 6-point bracket, can be focused and gives an erect image
. (In fact, its optics appear to be the same used in small roof-prism binoculars.) The right-side-up image is a welcome innovation for beginners who inevitably find the upside-down images of most finders confusing.
Their 7 [degrees] field and erect image
make locating objects fast and easy.