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Re: Re: colorsync-users digest, Vol 3 #311 - 7 msgs
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Re: Re: colorsync-users digest, Vol 3 #311 - 7 msgs


  • Subject: Re: Re: colorsync-users digest, Vol 3 #311 - 7 msgs
  • From: <email@hidden>
  • Date: Tue, 23 Jul 2002 17:17:34 -0400

> Dynamic Range: This is theoretical, not exact.
>
> 0.0 to 4.0 with 0.0 being White and 4.0 being Carbon Black.
>
> Each step towards 4.0 equals 2X as dense. I believe it works like this:
> (algorithmically)
> 0 = X
> .1 = X2 2X more dense
> .2 = 2X2 4X more dense
> .3 = 2X2X2 8X more dense
> .4 = 2x2x2x2 16X more dense
> .5 = 2x2x2x2x2 32X more dense
> .6 = 2x2x2x2x2x2 64X more dense
> .7 = 2x2x2x2x2x2x2 128X more dense
> .8 = 2x2x2x2x2x2x2x2 256X more dense
> .9 = 2x2x2x2x2x2x2x2x2 512X more dense
> 1.0 = 2x2x2x2x2x2x2x2x2x2 1024X more dense
>

Color Reversal (Transparency) Film, like Ektachrome, has an exposure latitude (dynamic range) of about 3.5 relative log exposure (rel. log H) units. Color Negative film has a latitude of about 4 rel. log H units.

Each increment of 0.3 rel. log H units equates to a doubling of exposure (inv. Log10(0.301)=2) which is 1 stop. So, color neg. has a latitude of 4.0/0.3 or about 13.3 stops, while reversal has a latitude of 3.5/0.3 or 11.7 stops. The spec sheet for the high-end BetterLight scan back lists a dynamic range of 11 stops, so this is just a bit under the capabilities of reversal film. Color negative film would be the optimum choice for capture - as long as there is access to a good color neg. film scanner.

In comparing film latitude to CCD dynamic range in this context, scanner dynamic range remains a consideration.


> At least:
> Newsprint 1.8
> Coated Paper 2.0
> Photographic Print 2.6
> Photographic Transparency 3.0 16X more dense then Photo print
> Digital Cameras 3.6 64X more dense then Photo transparency
> Digital Scanners 3.6
>

I'm not sure I understand this summary, but it seems conclusions were being drawn from the erroneous "belief" stated above and that this summary is a non sequitur.

-Chris
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