Archived posting to the Leica Users Group, 2000/02/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> The "bucket" shaped CCDs and the need for > parallel light rays sounds like hooey to me. The play in the mount causing > problems again is not true. Light behaves the same regardless of the medium > which is used to record it. Film, CCD, glass plate, whatever. CCDs do not > need light to be "more" focused than film! Depth of field changes with image > magnification and aperture not recording material. The explanation is indeed hooey, but there is a need for a low-pass filter in front of the light-sensitive elements in order to avoid aliasing. This is pretty much the same as A/D sampling in audio, and an attempt to record a higher frequency than the threshold would result in aliasing. However, the low-pass filter, which looks like a very thin ground glass (often a bundle of glass fibres) is not part of the image forming optical system, and is itself not a explanation why normal 35mm photography lenses are not suitable for digital photography. As John wrote, the size of the CCD, thus controlling the angle of field is the main issue.