I MA gE C APTuR E meter,thentheincidentmeterwillneedtobeadjusted tocompensateforthesensorbiasinrelationtotheISO setting.Inourcameratesting,wenoticedthatdifferent manufacturers have different philosophies toward matching the metering and sensors response to ISO values.Figuringoutwhatyourcameraactuallydoesin this regard is crucial to achieving optimal exposure. Achievingoptimalexposureindigitalcaptureiscrucial inachievingthebestpossibleimagequality. Onceyouhavedeterminedwhetheryouneedtoapply exposure compensation, the next step is to determine howtherawprocessoryouuseinterpretsyourcam- era'sfiles.Differentmanufacturesdefinerawsaturation (basically when the sensor reads "full") differently. Consequently, the middle-gray exposure point can vary by as much as 1 stop. An example of this effect saturation(highlightclippingpoint),willreducenoise and posterization--especially in the shadow areas. The earlier (especially CCD) digital cameras had a tendencytolosehighlightdetailorexperiencebloom- ingwhenoverexposed,sotheprevailingrecommenda- tionwastoslightlyunderexpose.Newercamerashave mechanisms to drain off light overflow, preventing blooming;however,overexposingwhenshootingJPEG files still results in loss of highlight detail due to the film-like tone curves that the in-camera processing appliesbeforeitdiscardstherawdata.JPEGexposure needstobeaspreciseasanpossibletoensureyouget whatyouneed. Rawfiles,ontheotherhand,cangiveoptimumquality GOOD FOR RAW FILES NOT GOOD FOR JPEGs