what's the dynamic range of the DMR?

[EH21]

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Hi,

I have been curious to know what the dynamic range of my DMR is. It seems to be about a stop or possibly two more than my Canon 5d but I'm not sure. Did a search in the forums here but didn't see anything. Anyone know? I have been considering moving to a medium format back for more dynamic range but am wondering if I would get any more than the DMR?

Thanks,

Eric

[gogopix]

lots of discussion and debate DMR vs the M8 . However, I have both Phase One P45 and DMR and the DR seems comparable. The M8 APPEARS similar, but does it by keeping the 14-16 bit DR but compressing to 8 bits

the DMR appears to retain 16 bit throughout (although I think the Kodak sensor is inherently a 14 bit device.

 

Pretty good in anybody's book!

 

regards

[Jamie Roberts]

What Victor said.... the DMR rocks, especially at low ISOs (since DR is limited by noise).

 

Of course, the difference in DR with the DMR vs 5d is lessened quite a bit by the fact that over ISO 400 the 5d has so much less noise that the effective DR quickly equalizes; over 800 ISO there is simply no contest, since the noise floor on the DMR is so high.

 

The M8 has at least a stop better noise than the DMR, and so maintains more effective DR above ISO 400.

[rosuna]

Sensors have not bit-depth. The Analog/Digital converter distributes the (electric) information in a tonal space. The DMR seems to have a 16bits converter, but 16bits converters are very, very unusual. The M8 could be using a 16bits converter too, but the output is "cleaned" for noise-affected zones by reducing it to 14bit (this is suggested by the LFI article). The Mamiya ZD, for instance, has a 14bit converter, and the new Canon 1D Mark III has a 14bit converter too (12bit in the previous models, just like the Nikons and many other cameras). You don't need a 14 bit ouput space if the sensor doesn't catch enough tonal differences. The dynamic range is also bounded (but not determined) by bit-depth.

[graham_mitchell]

There seems to be a common misconception that bit depth and DR are the same thing. They are not. It's quite possible to build a 16 bit sensor with only 1 stop of DR.

[gogopix]

good point Graham

 

also goes the other way; it is why the DR of the M8 can be 12 stops with only 8 bits.

 

The DR represents the top and bottom light intensities that are at the white point and black point of the sensor. The bits tell youy how much DETAIL there is in the shades of grey in between.

 

In the extreme, you can have a sensor with 1 bit, and 12 stops of DR; everything black untill 2**12 light intesity hits, then the bit is "ON" and you get white!

 

If you take a camera, point it at the sun and use 16 bits and a netral density filter you can get all the variations on the surface of the sun! (Not quite how the H alpha cameras work, but you get the point- 'lots of highlight detail, but the foreground (that nice blue sky and clouds) will be BLACK!

 

regards