exposure and light meters
Raw format exposure considerations One of the big topics of conversation since the release of Photoshop CS has been the subject of ‘Raw’ files and ‘digital negatives’. This section of the chapter guides you through the advantages of choosing the Raw format and the steps you need to take to process a Raw file from your camera in order to optimize its exposure.
All digital cameras capture in Raw but only digital SLRs and the medium- to high-end ‘Prosumer’ cameras offer the user the option of saving the images in this Raw format. Selecting the Raw format in the camera instead of JPEG or TIFF stops the camera from processing the color data collected from the sensor. Digital cameras typically process the data collected by the sensor by applying the white balance, sharpening and contrast settings set by the user in the camera’s menus. The camera then compresses the bit depth of the color data from 12 to 8 bits per channel before saving the file as a JPEG or TIFF file. Selecting the Raw format prevents this image processing taking place. The Raw data is what the sensor ‘saw’ before the camera processes the image, and many photographers have started to refer to this file as the ‘digital negative’. The term ‘digital negative’ is also used by Adobe for their archival format (.dng) for Raw files.
The sceptical among us would now start to juggle with the concept of paying for a ‘state-of-theart’ camera to collect and process the data from the image sensor, only to stop the high-tech image processor from completing its ‘raison d’être’. If you have to process the data some time to create a digital image why not do it in the camera? The idea of delaying certain decisions until they can be handled in the image-editing software is appealing to many photographers, but the real reason for choosing to shoot in Camera Raw is QUALITY.
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