DXOmark, 12 vs 14 bit

[Tjaika]

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I see that the D3x get one stop better DR than the A900 and two stops better than the 5DII. It translates to 13 bit DR as far as I understand.

Does this mean that A900 max out the 12 bit and the extra stop (or 1 bit) comes from the 14 bit resolution? The tradeout for the D3x is lower FPS (5 on 12bit and 1,3 or so in 14 bit) It could seem that the A900 is a good comprimise then for under half the prize and that the sensor itself outres 12 bit DR.

(if I have misunderstood something here please enlighten me)

 

[Nikolai Vassiliev]

bits doesn't means EV!!!

bits is only quantizations steps
more bits - more steps to describe brightness values

theoretically 14 bit vs 12 can provide a little more detail in very deep shadows

(but havy raw processing in D3X will kill it definitely before raw file was written)

for examples see photoclubalpha findings on a900 & D3X raws

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http://www.flickr.com/photos/qwz/
http://www.pbase.com/qwz/selected/

 

[Tjaika]

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I am not quite sure what you mean. 13 bits carries twice the information than 12 bits, right. Do you mean that 13 bits of DR is obtainable in a 12 bits raw?

 

[Tom Harvey]

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I am not quite sure what you mean. 13 bits carries twice the
information than 12 bits, right. Do you mean that 13 bits of DR is
obtainable in a 12 bits raw?

Bit depth and dynamic range are not directly connected.

• Dynamic range is the total range from dark to light that can be recorded by the sensor.
• Bit depth is how many steps of data are recorded (or how the range is sliced up).

A sensor with a small dynamic range can still (theoretrically) record 14 bits of data. It just slices the range into smaller slices.

A sensor with a huge dynamic range might only record 8 bits worth of depth - the slices will be larger.

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Tom

 

[Masterijn]

With the current "ISO noise" 12 bits should be more than enough.
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A700