Archived posting to the Leica Users Group, 2006/06/15
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Didier is 100% correct..... the implication ( logical implication not practical implication ) is that if Leica had decided to make a Digi-M using more WA lenses, they should have picked the R lenses as target lenses... an R mount RF camera. Interesting thought? Frank Filippone red735i@earthlink.net You ignore one problem. RF lenses and SLR lenses are absolutely not akin when it comes to the angle of the incoming light rays, which is a crucial factor for digital sensors, but not for film emulsions. Many RF lenses protrude deeply into the camera body, and the light that goes from the back side of these lenses to the corners of the 24x36mm film frame, can have an angle significantly lower than 90 degrees. Film emulsions react quite indifferently to this as the three-dimensional emulsion grains can be exposed from the side, too. But a sensor needs the light coming in at a 90? angle, and does overproportionally underexpose the lower this angle gets. SLR lenses have another design because of the mirrorhouse. They're more away from the film/sensor plane, and the angle of the incoming light is straighter. This explains why a digital sensor in RF camera produces more vignetting than the same would in a SLR. But nonetheless most SLR lens producers have redesigned their lens lines for this reason, and for the crop factor and have added new coatings at the back side of the lenses to prevent light reflexions from the sensor.