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dynamic range

Discussion in 'X-T2, X-T1, X-T20, X-T10' started by fujiphile20, May 19, 2017 at 10:01 PM.

  1. fujiphile20

    fujiphile20 Member

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    My understanding is that dynamic range is the spectrum that the camera interprets as white to black but, I have notice that dynamic range can be increased by stops. What disadvantage would this have since I should be able to expand the range and retain information in my highlights.


    thanks-
     
  2. ysarex

    ysarex Premium Member

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    Not really sure what you're asking here. DR (dynamic range) is a fixed property of a digital camera's sensor. It has a maximum physical value that is not adjustable -- can't be increased. When digital cameras are used in conditions that require an increase in the camera's ISO value DR is truncated by the underexposure and commensurate ISO brightening boost. You can see that progression for an X-T2 in this chart: Photographic Dynamic Range versus ISO Setting (many thanks Bill Claff).

    Are you asking about the Fuji DR200/400 functions? Fuji includes this function to provide alternative JPEG processing for use in high contrast lighting conditions. This function will render a JPEG processed with a lower contrast tone curve which does a better job retaining both highlight and shadow detail than the standard JPEG processing. Paradoxically, when used in accordance with Fuji's design, this function actually sacrifices sensor DR to achieve it's result. In other words the raw files produced when this function is used will typically suffer from reduced DR due to underexposure even as the camera JPEG benefits. So if your question concerns this DR200/400 function then the advantage you gain is the special JPEG processing. The disadvantage is typically a compromised raw file. If you want the JPEG use the function. If you want a raw file avoid it like it was a plague.
     
    rixpix, charlie3, NewmanX and 2 others like this.
  3. fujiphile20

    fujiphile20 Member

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    fantastic explanation. I understand. I was speaking about the DR 200 feature which is associated with JPEGs not Raw and it makes sense how it would compromise raw files but improve jpeg images retaining of highlight and shadow.


    many thanks
     
  4. MA128

    MA128 Active Member

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    ysarex - good to know. Thanks!
     
  5. elisha.jesudason

    elisha.jesudason Member

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    So the in camera DR setting affects RAW too?
    I thought it was purely a jpeg thing like Dynamic Lighting in Nikon.
     
  6. F2Bthere

    F2Bthere Premium Member

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    Great clarification!

    One point to add...the dynamic range of a camera and sensor combination cannot be increased, as far as I know (conceivably someone will come up with som slick trick we haven't imagined at some point), but...you can increase how much of the dynamic range you can capture in a given scene by exposing to the right using RAW files and processing the image correctly in post processing. This is commonly referred to as ETTR.
     
  7. ysarex

    ysarex Premium Member

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    In a Nikon the ADL function likewise effects the raw capture. This is becoming a standard function on modern cameras. Nikon has its ADL variant, Canon has their version (HTP), Pentax has it, Sony has a version, Fuji has DR, etc. They all tend to approach the problem in similar fashion with some twists. The problem is high contrast lighting. An averaged exposure of the scene is unsatisfactory because the shadows are too dark and yet the diffuse highlights may still be starting to clip. All the manufacturers then make the same first assumption: You're taking the metered exposure and the diffuse highlights are starting to clip. First step is to reduce the exposure which ideally is pulling those diffuse highlights back away from clipping and this is where the raw file takes a hit -- reduced exposure. Second step is to apply a special tone curve to render the JPEG brightened, lower contrast and with the shadows lifted.

    Fuji's approach: To achieve the first step in the process (reduced exposure) Fuji forces an ISO increase. You can't use the DR200/400 function with the camera set to base ISO. When you increase ISO the camera meter re-calculates a reduced exposure. Under normal conditions the camera would then take the sensor signal and boost it (analog gain and/or digital scaling and/or both) during the ADC (analog digital conversion) process to create the raw file. This signal boost normalizes the raw file to permit standard JPEG processing. Under the DR200/400 condition the sensor signal boost is withheld and the raw file metadata gets tagged by the function. This is the way in which Fuji's DR function effects a raw file: The DR200/400 raw files lack the normal signal processing through ADC that we expect when the camera is used with ISO values above base.

    It really boils down to do you want the camera JPEG. If you want the camera JPEG use the function and get the JPEG. If you want a best raw file you'll adopt a different procedure.
     

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