Archived posting to the Leica Users Group, 2006/09/19

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: [Leica] Re: the dynamic range of digital
From: telyt at (Douglas Herr)
Date: Tue Sep 19 22:41:12 2006
References: <>

B.D, why don't you re-read the article you've thougtfully pointed us 
toward and tell me how Reichmann's analysis of a 12-bit device 
interpolated to 16 bits applies to a native 16-bit device that he has 
never used?  How does he support his blanket assertion that digital 
cameras are 5-stop devices?  Is he assuming a 12-bit camera?  As I'm 
sure you know with your vast technical background (a background which 
no doubt led to your brilliant prediction of the DMR's failure both in 
the marketplace and as a competetive image-making device) each 
additional bit of real data doubles the number of values that can be 
measured and stored.  The additional bit can be used either to expand 
dynamic range or to produce smoother tonal gradations, or some of both 
depending on how the device is programmed.  Now, tell me again how 
Reichmann's analysis of a 12-bit camera applies to a 16-bit camera?  
Let's see, 16-12 = 4 so there's 2^4 = 16 times as many data values 
available in the 16-bit camera.

What real-world experience do you have with the DMR?  Re-read my posts 
on this subject:  by setting the exposure compensation to -.5 to -1 I 
avoid clipping the highlights - that's what I wrote.  This seems to be 
common practice among DMR users, possibly the way the equipment is 
calibrated; no doubt you'll say it's an example of how much of a 
failure the DMR is.  It's done just to keep from throwing highlight 
data away.  Tell me again how keeping highlight data instead of 
clipping means throwing data away?

Reichmann's assumption - the one you apparently have swallowed hook, 
line and sinker - is that all digital cameras behave the same way.  
What I'm doing is keeping the full histogram - exclusive of specular 
highlights - within the liberal confines of the 16-bit space, snugged 
over to the right just as Reichmann suggests.  On the DMR, something 
you are clearly not familiar with, this is done by setting the exposure 
compensation to about -.5 to -1.0.  Call it a quirk of the equipment or 
of the firmware, that's how it's done.  I'm not throwing data away, I'm 
keeping highlight data from being thrown away.

B.D., this is clearly another case of you spouting off thinking that 
you've researched the subject when you're taking someone else's 
analysis out of context.  You're really just displaying your technical 
ignorance and how quickly you jump to conclusions.

Doug Herr
Birdman of Sacramento

On Sep 19, 2006, at 7:58 PM, B. D. Colen wrote:

> Being the digital expert you are, Doug, I would have thought that 
> you'd know
> that by under exposing a stop, you're throwing away everything at the 
> top
> end of the range - in the highlights - not the shadows - and 20% of 
> the data
> is in that top stop. But I don't use a DMR, so of course I know nothing
> about digital ;-) - so don't listen to me, but do try reading 
> this...from
> the Luminous Landscape site....
>> In my experience with the DMR, setting exposure comp to -.5 or -1
>> sacrifices very little deep shadow detail if any.  It's not what I'd
>> call a 20% loss of data.  The histogram (yes it's RGB) is nowhere near
>> clipping at either end aside from specular highlights.  Perhaps B.D.'s
>> 20% estimate is based on his experience with the E-1?
>> Doug Herr
>> Birdman of Sacramento
>> _______________________________________________
>> Leica Users Group.
>> See for more information
> _______________________________________________
> Leica Users Group.
> See for more information

Replies: Reply from bd at (B. D. Colen) ([Leica] Re: the dynamic range of digital)
In reply to: Message from bd at (B. D. Colen) ([Leica] Re: the dynamic range of digital)