all this assumes that the maximum value in 8 bit mode is the same as in RAW mode. according to reviews and tests, they aren't. the maximum in RAW mode is typically higher by anywhere from half a stop to a full stop more depending on the size of your highlights. you can still blow the highlights, but you have a little bit more room. the conversion in-camera compared to Photo Laboratory is different and that is why you have to try with Photo Laboratory.
Herb.... ----- Original Message ----- From: "Pieter Nagel" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, December 29, 2003 8:16 PM Subject: Re: Dynamic Range > I'm not sure whether RAW actually gives you one more stop of dynamic > range/sensor acceptance range. That might be an impression created by the > Pentax software, which I do not use (I use Linux, dcraw, cinepaint, and > gimp 1.3). > > It is plausible that, when shooting JPG, that the JPG is derived from the > entire dynamic range of the RAW (i.e. RAW 0 -> 4095 is mapped to > JPG 0 -> 255) - but of course there are less gradations of tonality > inbetween in the JPEG. I think the black point and the white point of the > JPEG are chosen based on a combination of thumbsuck, heuristics, the shape > of your histogram, and your contrast setting, and it need not be true that > there is an extra stop available either below the black or above the white > of your JPEG. Sometimes, but not always. > > However, even in those cases, should you choose to only use the rightmost > 2/3 range of your exposure, you can do that with RAW and it's finer > gradation of tonality, without posterisation. > > How does the RAW -> JPEG conversion of the Pentax software compare to what > happens in-camera? If it is similar, I could do some experiments to see > exactly how the dynamic range of the RAW and the JPEG relate.
