[Leica] New Monochrome? Mark

[philippe.amard]

Le 15 janv. 15 à 10:09, Mark Rabiner a écrit :

>  I'm not sure if we have a real
> sense of what iso we can use it at now?!?


This might help add to our confusion circle ;-)


DR Modes and the ISOless APS-C Sensor

You may have heard that Fuji’s APS-C cameras are all based on modern  
“ISOless” Sony sensors. These sensors are used by several leading  
camera manufacturers, such as Sony (of course!), Nikon, Ricoh/Pentax,  
Leica and Fujifilm.

The “killer feature” of ISOless sensors is their ability to rely on  
digital gain (as opposed to analog amplification) for the most part of  
their operation. Digital gain can be applied anytime during your  
workflow—before and after the RAW file has been created. As a matter  
of fact, it’s better to apply digital gain after the fact—when the RAW  
in processed in a converter. This is also the reason why Fujifilm RAWs  
don’t go beyond ISO 1600. They remain the same—any further gain  
between ISO 1600 and ISO 6400 is applied digitally during RAW  
conversion.

This means that in high-ISO scenarios, achieving “perfect exposure”  
before you press the shutter button doesn’t really matter. You can  
just as well change the exposure later in the RAW processing phase— 
either in-camera, or with Lightroom (or with another RAW converter) in  
the comfort of your home. Click here to read a forum thread with a  
demonstration of this feature.

Between base ISO 200 and ISO 1600, “mixed” analog/digital  
amplification maintains a slight quality advantage over “pure” digital  
gain. That’s why your camera is still using at least some analog  
signal amplification up to ISO 1600. Enabling the DR function  
basically switches the mixed analog/digital process over to a pure  
digital gain (or tone-mapping) process for either one (DR200%) or two  
(DR400%) analog signal amplification stops.

Let me give you an example: Shooting an image at ISO 800, DR100% will  
result in an ISO 800 RAW file that’s based on an ISO 200 exposure with  
two stops of mixed analog/digital amplification/gain. Shooting the  
same image at ISO 800, DR400% will result in an ISO 200 RAW file with  
digital tone-mapping being applied during RAW conversion. This tone- 
mapping is pushing the result to ISO 800 in the shadows and midtones,  
while retaining bright highlights at ISO 200. You would have a hard  
time telling the “analog” from the “digital” ISO 800 result when  
looking at the shadows and midtones. You will however recognize that  
the digitally processed DR400% version offers two additional stops of  
highlight dynamic range. This is exactly what we want when shooting  
scenes with high DR, like christmas markets with festive lights and  
very strong contrasts.

In other words: Yes, sensors have a fixed dynamic range, but the  
actual dynamic range that can fit into your actual image file is not  
just determined by the sensor, but by the signal processing and by  
whatever happens during RAW processing. By applying “adaptive ISO”  
during RAW processing, you can expand the actual dynamic range of any  
image by 1, 2, 3 or even more stops. The sky’s the limit, but for  
practical reasons, there will always be quality considerations, since  
the application of digital gain results in a similar image degradation  
as raising ISO values the old-fashioned way.





Much more at : http://www.fujirumors.com/exposing-right/

Amities

Ph







One sees clearly only with the heart. What is essential is invisible  
to the eye. Antoine de Saint Exupéry in Le Petit Prince.
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