Archived posting to the Leica Users Group, 2006/01/11
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]David, You are looking at the process incorrectly. Based on analysis of how light hits the exposure meter based on focal length used and aperture selected the computer in the camera sets the correct exposure. In a simplistic case, no different than the offsets that were used with various screens on the old Photomic finder for the F. Canon, and I presume everyone else, has figured out that the light ray bundle coming out of the exit pupil appears different on the screen than on the sensor surface used. After doing the research they developed an equation that uses EI, aperture, lens used, focal length selected, and I presume distance to skew the exposure to one that presents a generally pleasing image onto the sensor. If the lens doesn't communicate this information to the onboard computer then you get back a default value that may be less pleasing. The end result is that if you use a non-chipped lens on a Canon body you are back to using your brain to interpret the light and how it affects the exposure; or take an exposure and check out how it looks on screen and histogram. Getting off on the deep end, I believe that Canon's low noise at high ISO's is based on the sensor design and the software that interprets the information coming out of the chip. Nikon in parcticular must be using a noise reduction algorythym as they have less noise at high EI than competitors using the same chip. Don don.dory@gmail.com On 1/11/06, David M. Dorn <dmdorn_ct_usa@mac.com> wrote: > > If the chip in the camera lens adjusts to compensate for proper > exposure as in the example given, 400ASA to 200ASA, doesn't this point > to the fact the the Cannon's touted "low noise" is really somewhat > hyped? If I set my ASA to 400 but the camera is really using 200, then > I would expect the noise to be less. I assume one could test this by > making reading with an incident meter of a test card and then compare > the camera's exposure setting with the meter's reading. I would do so > but I still only shoot film :-) > > Regard, > > David > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >