Archived posting to the Leica Users Group, 2001/11/06
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]OK - now I understand a bit more. Thanks. But it is not impossible to use Leica lenses on a digital camera. All the best! Raimo Personal photography homepage at http://personal.inet.fi/private/raimo.korhonen - -----Alkuperäinen viesti----- Lähettäjä: Jim Brick <jim@brick.org> Vastaanottaja: leica-users@mejac.palo-alto.ca.us <leica-users@mejac.palo-alto.ca.us> Päivä: 06. marraskuuta 2001 17:58 Aihe: [Leica] digit stuff for those interested >I was told, off line, the following: > >"Fact is, your bringing up digital 4x5 lenses, when talking about a Leica, is >just ludicrous and you should know it." > >Since I wrote a response, I decided to share it with the group. > >The parallel is that the "film" 4x5 lenses are too sharp, their MTF is too >high for digital sensors, just like MTF of Leica lenses is too high for >digital sensors. So Schneider (and others) designed a set of lenses with a >MTF that is matched to digital sensor spacing. And wrote a white paper >explaining the facts and why they had to do this. Which is why Leica will >not mount an M lens on a digital camera. They have designed new lenses for >their partnered (Panasonic) cameras. The Canon and Nikon SLR lenses that >are used on their respective cameras are not redesigned, but the cameras >contain low-pass filters to "dumb down" the lenses before the image gets to >the sensor. > >The bottom line is that all lenses are equalized by digital sensors. A >leica lens is no better or worse than a Sony or Olympus or whatever lens. >The things we buy Leica lenses for are lost in the digits. In film, a 1 >micron square silver halide grain contains 20 Billion silver halide >molecules, each capable of being hit (exposed) by a photon. It only >requires three being hit to produce a developable speck. A digital sensor >pixel (the minimum recording spot) is 5 microns square (25 sq. microns vs 1 >sq micron) and will ultimately report a light level of 0-255 (256 levels) >for this whole vast area of 25 sq. microns. This is why Leica lenses out >perform most other lenses on film, but are no better than anything else on >pixels. And why film can record deep shadows and bright highlights in the >same scene. Digital sensors cannot. All fine detail (Leica's strong point) >is completely lost. Digital cameras are digital cameras. Their integration >into a film camera body by Canon, Nikon, Kodak, & Fuji is simply to give >professional photographers a known base to start from. The professional >level digital cameras from Olympus and others that don't look like >traditional SLR's and have non-interchangeable zoom lenses produce >photographs equal in every way to the SLR interchangeable lens cameras. >They just aren't "familiar" to the pro photographer. > >Astro photographers have the same problem. But instead of dumbing down the >lens, they shift the sensor half a pixel in four quadrants, take four >exposures, and then analyze the result with software to pick up points that >fall in between pixels and to differentiate double stars from single large >objects. A static CCD sensor cannot record these (and other) phenomenon. >And without either dumbing down the lens MTF or taking multiple exposures >and processing the results via software, serious aliasing occurs that is >not fixable with software without producing other artifacts. None of these >problems occur using film. But film has to be processed and scanned to get >the image into a computer for analysis. > >Basically, digital cameras are digital cameras. The digital sensor is the >great equalizer. All lens/camera brands sharing similar sensors and price >will perform equally. Only the post processing software can make a visual >difference. Lens performance is completely lost. And it will remain this >way as long as the 5 micron square pixel is the smallest obtainable. > >Jim > - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html