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dynamic range



 
 
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  #1  
Old February 14th 06, 11:13 PM posted to rec.photo.digital.slr-systems
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Default dynamic range

Could there be a filter to increase dynamic range? Kinda like a
polarizer that blocks bright light while letting in dim shadow detail?
As I understand, whatever the camera is capable of capturing before the
highlights blow is squeezed into the same file format between black &
white so a high DR camera is actually going to be a bit less contrasty.

What are the DR ratings for various DSLRs?


16bit vs 8 bit for prints
wrote:

The dynamic range is a ratio, not a height. The maximum dynamic range
expressable at the pixel level is the ratio of the luminance of the
highest value to the lowest. If the values are linear, then the dynamic
range of 16-bit is 257 (65535/255) times as high as 8-bit; if the
shadows are 2.2 gamma-adjusted, 16-bit data has a potential dynamic
range 196,000x as high as 8-bit. Common standards use linear data for
deep shadow ranges, I have been told, so the more probably figure is
257. 16-bit conversions have a little bit more dynamic range than 8-bit
conversions for low-noise ISOs (provided they are both TIFF; if the
8-bit is JPEG, then the difference is wider).

The real limitation to dynamic range is the RAW data itself (at low
ISOs) and noise (at higher ISOs). 2.2-gamma 8-bit data can hold a lot
of DR, and 16-bit astronomical DR. The limitation is precision in the
8-bit data.

  #2  
Old February 14th 06, 11:19 PM posted to rec.photo.digital.slr-systems
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Default dynamic range

Paul Furman wrote:

Could there be a filter to increase dynamic range? Kinda like a
polarizer that blocks bright light while letting in dim shadow detail?
As I understand, whatever the camera is capable of capturing before the
highlights blow is squeezed into the same file format between black &
white so a high DR camera is actually going to be a bit less contrasty.


Or you can just have the raw converter (or jpeg creation) extract
something less contrasty and apply curves to that to put the contrast
where it's desired... but even then, I sometimes have to do multiple raw
conversions to recover blown highlights.
  #3  
Old February 14th 06, 11:31 PM posted to rec.photo.digital.slr-systems
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Default dynamic range


"Paul Furman" wrote in message
t...
Paul Furman wrote:

Could there be a filter to increase dynamic range? Kinda like a polarizer
that blocks bright light while letting in dim shadow detail? As I
understand, whatever the camera is capable of capturing before the
highlights blow is squeezed into the same file format between black &
white so a high DR camera is actually going to be a bit less contrasty.


Or you can just have the raw converter (or jpeg creation) extract
something less contrasty and apply curves to that to put the contrast
where it's desired... but even then, I sometimes have to do multiple raw
conversions to recover blown highlights.


No filter can increase dynamic range unless one is willing to expand the
range after the fact of a limited/filtered selection. Kind of a cheat, by
the way. You can initially clip the dynamic range and then later expand it.
So, my answer is basically NO. This could be an interesting thread!


  #4  
Old February 15th 06, 12:32 AM posted to rec.photo.digital.slr-systems
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Default dynamic range


"Paul Furman" wrote in message
t...
Could there be a filter to increase dynamic range?


Not a filter, it would add its own 1-2% reduction (assuming quality
coating on all lens groups). A well configured lens hood *will*
increase Dynamic range, especially if the lens isn't spotless clean.

Bart

  #5  
Old February 15th 06, 12:38 AM posted to rec.photo.digital.slr-systems
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Default dynamic range


"Paul Furman" schreef in bericht
t...
Could there be a filter to increase dynamic range? Kinda like a polarizer
that blocks bright light while letting in dim shadow detail? As I
understand, whatever the camera is capable of capturing before the
highlights blow is squeezed into the same file format between black &
white so a high DR camera is actually going to be a bit less contrasty.

What are the DR ratings for various DSLRs?



There are filters which in some circumstances make a picture less contrasty.
That would mean that in those circumstances you actually can record a
scene with more dynamic range. Later on you can use part of the dynamic
range
to get the picture you actualy want, or you can stretch the dynamic range to
obtain a dynamic range which represents the reality a bit more.
I do not now how to make such dynamic range visible though. (Not on screen,
not on paper).
And I don't think that filters which reduce the contrast will improve the
picture.


ben brugman


  #6  
Old February 15th 06, 12:42 AM posted to rec.photo.digital.slr-systems
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Default dynamic range


"Paul Furman" wrote in message
t...
SNIP
What are the DR ratings for various DSLRs?


They can/could extend to the full 12-bit (4095:1) range that the
DSLR's ADC provides, give or take half a bit quantization error.
Boosting that to the 32767:1 or 65535:1 working space range will help
to allow for post-processing rounding errors, before reducing that to
the 126:1 printing range.

Bart

  #7  
Old February 15th 06, 04:25 AM posted to rec.photo.digital.slr-systems
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Default dynamic range

In message ,
"Charles Schuler" wrote:

No filter can increase dynamic range unless one is willing to expand the
range after the fact of a limited/filtered selection. Kind of a cheat, by
the way. You can initially clip the dynamic range and then later expand it.
So, my answer is basically NO. This could be an interesting thread!


Are you talking about something like the Tiffen "ultra contrast"
filters?

I played with that idea a while back, and my conclusion was that all it
basically did was raise the blackpoint of the RAW data, while decreasing
the effective subject exposure, so in effect, it basically increased
exposure latitude at the expense of exposure strength, and did not
increase DR at all (it actually reduced it). It is probably more useful
with film, or in lifting the shadows in camera JPEGs, than material for
RAW conversion.
--


John P Sheehy

  #8  
Old February 15th 06, 04:57 AM posted to rec.photo.digital.slr-systems
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Default dynamic range

Bart van der Wolf wrote:

"Paul Furman" wrote in message
t...

Could there be a filter to increase dynamic range?



Not a filter, it would add its own 1-2% reduction (assuming quality
coating on all lens groups). A well configured lens hood *will* increase
Dynamic range, especially if the lens isn't spotless clean.


Ben's contrast reducing filter is something I hadn't heard of, a little
googling suggests that tends to give a milky look similar to well
controlled flare. That suggests that a lens hood increases contrast
which is more likely to blow highlights & leave shadows buried.

filters:
http://www.tiffen.com/userimages/Con...ctSheet_Lo.pdf
discussion:
http://www.photo.net/bboard/q-and-a-...id=000F7D&tag=
  #9  
Old February 15th 06, 05:11 AM posted to rec.photo.digital.slr-systems
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Default dynamic range

I don't know about a filter but I know when using camera raw in
photoshop to open a raw image, you can alter the contrast which results
in more detail in shadows and (provided it is there in the first place)
highlights. It makes for a very flat looking picture but one which can
have it's attenuation increased with other tools to liven up the image.

My experience has been that under exposing when bright objects are
present by up to 2 stops allows you to use Photoshop tools the lighten
the dark areas while keeping the highlights under control. This also
results in flat looking pictures.

I think that until the sensors can capture a wider range of detail -
maybe closer to human vision - no digital camera and no filter will
produce a pleasant looking picture with the full range of such scenes
as would normally have blown highlights and blacked shadows.

Maddy

  #10  
Old February 15th 06, 05:52 AM posted to rec.photo.digital.slr-systems
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Default dynamic range

wrote:

Are you talking about something like the Tiffen "ultra contrast"
filters?

I played with that idea a while back, and my conclusion was that all it
basically did was raise the blackpoint of the RAW data, while decreasing
the effective subject exposure, so in effect, it basically increased
exposure latitude at the expense of exposure strength, and did not
increase DR at all (it actually reduced it). It is probably more useful
with film, or in lifting the shadows in camera JPEGs, than material for
RAW conversion.


It seems to be the same idea as "flashing" paper (or film) in the darkroom
to raise the black level out of the bottom of the "toe" of the response
curve. That would seem to be inapplicable to RAW capture.

--
Jeremy |
 




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