There are two basic configurations of autofocus sensors used in SLR cameras. Linear sensors detect lines in one direction only – usually just vertical lines, though some camera sensors, such as the EOS 10/10s outer sensors, can detect only horizontal lines. Others, known as cross or cross-shaped sensors, can detect both vertical and horizontal lines. With their higher sensitivity, cross sensors are considerably more accurate than linear sensors, particularly in lower-light conditions. Some cross sensors are also high-precision sensors (see below). Most EOS cameras with multiple focus points have a cross sensor as the central point and vertical-line sensors as the other points. So in challenging focus situations it s usually best to switch manually to the centre sensor so you get the full benefits of the cross. Note that the first generation of EOS cameras (600 series) and most early Rebel/three or four digit film cameras do not have cross sensors.
There are two basic configurations of autofocus sensors used in SLR cameras. Linear sensors detect lines in one direction only – usually just vertical lines, though some camera sensors, such as the EOS 10/10s outer sensors, can detect only horizontal lines. Others, known as cross or cross-shaped sensors, can detect both vertical and horizontal lines. With their higher sensitivity, cross sensors are considerably more accurate than linear sensors, particularly in lower-light conditions. Some cross sensors are also high-precision sensors (see below). Many EOS cameras with multiple focus points have a cross sensor as the central point and vertical-line sensors as the other points. So in challenging focus situations it s usually best to switch manually to the centre sensor so you get the full benefits of the cross. Note that the first generation of EOS cameras (600 series) and most early Rebel/three or four digit film cameras do not have cross sensors. A few recent digital cameras have all