[Leica] Re: "the dynamic range of digital"

[hoppyman at bigpond.net.au (G Hopkinson)]

Thanks Rob. Those are interesting and useful links. I grasp the fundamentals 
of the expose to the right approach, without clipping;
as first espoused by Doug. There's quite a bit of other info emerged here, 
regarding the performance of different sensor/firmware
combos. I'm scanning film in 14 bit, upsampled to 16 bit and the various 
histogram options, raw, luminance and RGB channels are
enlightening. Most especially from slide film.
Cheers
Hoppy


-----Original Message-----
From: lug-bounces+hoppyman=bigpond.net.au@leica-users.org 
[mailto:lug-bounces+hoppyman=bigpond.net.au@leica-users.org] On Behalf Of
Robert Schneider
Sent: Thursday, 21 September 2006 00:00
To: Leica Users Group
Subject: [Leica] Re: "the dynamic range of digital"

Hoppy,

I posted this link yesterday, but it bears repeating:

http://www.luminous-landscape.com/tutorials/expose-right.shtml

This piece was written in 2003, but again, I don't believe the laws  
of physics have changed in last three years.

Quote from the article:

Digital guru Ian Lyons has some comments on this technique with some  
insights as to how digital compares to what we've been used to with  
film...

Basically the ideal exposure is as Michael describes: get your  
histogram as close to the right side as possible but not so close as  
to cause the over exposure indicator to flash. The ideal exposure  
ensures that you have maximum number of levels describing your image  
without loosing important detail in the highlights. The closer you  
get to this ideal then the more of those levels are being used to  
describe your shadows. If you underexpose an image to the extent that  
the shadows block, which is often what folk do to protect their  
highlights; then you will need to open them again to ensure the final  
image is as you require. The problem with this approach is that we  
only have 128 levels available to the shadows. You start pulling  
curves, etc to open the shadows and you'll get posterisation, etc.

Again, HTH,

Rob




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