|Aspects of the Canon crossover-system.
||One of the common methods of 4:3 / 16:9 image switching by CCD is to cut off the image at both ends, leaving the centre portion as the effective image area. This results in a smaller image area for the switched 4:3 format (dia. 9mm) when compared to the 16:9 and conventiona1 4:3 formats (dia.11mm).
||As the diameter of the image shortens under the condition of the switched 4:3 format (dia. 9mm), the ang1e of the lens becomes more telephoto. Consequently we lose about 20% of the angle at the widest focal length in comparison with the 16:9 format (dia.11mm).
||To enable operations with the same picture angles in the two different format sizes, a 0.8x crossover unit is employed. This shortens the focal length of the lens to achieve the same angle as the conventional 4:3 format (dia. 11mm), under the switched 4:3 format (dia.9mm) condition. Accordingly a conventional 2.0x extender in the 16:9 format (dia.11mm) turns out to be a 2.4x extender under the switched 4:3 format (dia.9mm).
||The extender unit of the crossover system includes a crossover lens in addition to conventional extenders.