ruthenium wrote:
Dan, whether your "exposure changed for reasons related to the casual nature" of the test should be indicated by the shutter speed. If the shutter speed didn't changed (you haven't mentioned whether it did or didn't), then the exposure couldn't change (unless the camera has changed that secretly, while pretending it hadn't).
I did not check because it was a quick, informal test… and because it would not affect what I was looking for, namely the pattern of peaks aligning with grayscale patches on my target.
But when I get a chance, as I mentioned earlier, I’ll test again with all setting determined manually and kept the same from shot to shot.
I don't know why you thought that the camera dynamic range could expand with DR200 or DR400
Maybe because of that naming that suggests that you should get “200%DR” or “400% DR?” ;-)
quote] Considering that the dynamic range is defined as a ratio of the strongest signal to the noise (or to an arbitrarily set level corresponding to the weakest detectable signal, as in the photographic dynamic range from Bill Claff), then the only way to increase the dynamic range is by increasing the signal by increasing the exposure. [/quote
That is not making sense to me. Increasing exposure does not increase the potential recorded dynamic range. It merely shifts the luminosity range of the image to a brighter or less bright level. The sensor itself can record whatever dynamic range it can record.
The exposure can be increased only by reducing the shutter speed and/or by opening the aperture. This is why the dynamic range inversely depends on the ISO, because the ISO changes with exposure like temperature changes with the amount of heat (only, ISO scales as an inverse of exposure, while temperature increases with heat).
Sorry, you are not making sense. The object of these settings is to capture a wider dynamic range without losing shadows or blowing our highlights while keeping the exposure the same. That’s literally what the 200%DR and 400%DR settings claim to do.
I believe that they do not affect the actual raw signal — other than possibly suppressing the exposure a bit at the 400% setting to protect highlights as Jack thinks. And I’m not certain about that.
Looking at the histogram, the graphical representation of the intensity at each step of the gray scale image, the distance between peaks and more or less the shapes of those peaks does not really change. If the sensor were somehow recording a greater dynamic range either the dark tones would have to be lightened (by far the most likely on digital cameras) or somehow the highest peak luminosities would ahve to be reduced. Either of those would necessarly compress the range of the grayscale chart image so that it takes up a smaller percentage of the now-expanded raw file’s dynamic range.
That did not happen.
On the other hand, I do believe (though I did not test it, instead taking Fujifilm at their word) that when using the 400% and 200% settings the camera’s software is applying some kind of curve to the in-camera output of the raw signal from the sensor and (most likely, by far) bumping up the luminosity at the dark end of the scale by one or two stops.
As has been mentioned several times in the thread, that could be useful to jpg-only shooters who are not all that interested in post-processing and who want to take greater advantage of the cameras ability to deal with larger dynamic ranges. On the other hand, those with more sophisticated needs for image development and processing are probably going to shoot raw and not see much if any advantage from using these settings instead of simply exposing to protect highlights and recovering shadows in post as needed.