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 Post subject: Dynamic Range of 40D
PostPosted: Sat Oct 27, 2007 6:10 pm 
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Nice article from Bob Atkins: http://www.bobatkins.com/photography/di ... _3.html#dr
Seeing the curve you could wonder what 14bit processing is for, when the dynamic range is 10, max 11 stops. Well I was confused on this topic also, but this simply means you have 3bit (=14-11) for each stop so you can record slight exposure differences of 1/8th of a stop (per color)!
Am I right?

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 Post subject:
PostPosted: Sat Oct 27, 2007 8:00 pm 
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I would like to do some testing on this and have in fact recently bought a Stouffer wedge chart - I'm currently considering how best to use it and analyse and present the results...


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PostPosted: Sat Oct 27, 2007 9:03 pm 
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Veeeeery good. You know, Gordon, that I like the issue of contrast and dynamic range very much :!:
In my eyes that's the single most important issue in todays DSLRs :idea:

Looking forward to some real reliable and professional testing...

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 Post subject:
PostPosted: Sun Oct 28, 2007 8:16 am 
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I bought it with you in mind Thomas!

PS - "Looking forward to some real reliable and professional testing..." - what don't we already do that?!

Seriously though, Imatest has a module to analyse the Stouffer data, so that side is sorted. I just need to standardise on a light source and testing methodology.


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 Post subject:
PostPosted: Sun Oct 28, 2007 9:45 am 
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Gordon wrote:
What, don't we already do that?!

Yep, but no dynamic range tests so far at Camera Labs. So my remark was aimed to say "I wish CL would do these tests so that we get a professional and reliable source for those data" :idea:

Cant' wait...

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PostPosted: Sun Oct 28, 2007 11:38 am 
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My understanding is that the 14 bit A/D gives a finer quantisation of brightness levels rather than a greater range between the darkest and brightest parts of an image which can be accurately recorded. Christian Buil's 40D Test has some interesting comments on the subject.

I confess that when the 40D specs first came out I made the mistake of assuming the 14 bit A/D would allow for greater range rather than finer quantisation. I think there are real benefits to 14 bit A/D, however, even if with no significant increase in range. Quite apart from the very real benefits in photometry referred to by Buil, that finer quantisation would allow for more extreme intensity stretching in post-processing with fewer artefacts if one needed to highlight very small variations in intensity. A classic example, IMO, would be the lace and decorative stitching in a wedding dress (provided the dress wasn't overexposed in the first place).

Bob.

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