Question about dynamic range (No, not another "what is HDR")

Discussion in 'Beyond the Basics' started by Mr. Murmeli, May 4, 2009.

  1. Mr. Murmeli

    Mr. Murmeli TPF Noob!

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    Hi

    I got wondering: do some DSLR cameras handle dynamic range better than others? And also how do film cameras compare to digital ones in this aspect?

    We all know how useless the dynamic range is in a digital camera compared to our eye so i was thinking if this could be improved in the future. I was just shooting in the woods (weather was rather bright but cloudy) and almost all the pictures required either a graduated ND filter (which i don't have), or multiple exposures from the same place and then some annoying photoshop work afterwards.

    Thanks! ;)
     
    Last edited: May 4, 2009
  2. KmH

    KmH Helping photographers learn to fish Supporting Member

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    Actually, the dynamic range of the human eye sucks. Fortunately, it's connected to a brain which does all kinds of image processing (analog) to make it SEEM as if our eyes have a wide DR.

    "A human can see objects in starlight (although colour differentiation is reduced at low light levels) or in bright sunlight, even though on a moonless night objects receive 1/1,000,000,000 of the illumination they would on a bright sunny day: that is a dynamic range of 90 dB. A human cannot perform these feats of perception at both extremes of the scale at the same time." Like a camera can. "The eyes take time to adjust to different light levels and the dynamic range of the human eye in a given scene is actually quite limited due to optical glare." - Wikipedia

    Yes, some DSLR's have a wider DR than others but not by much.

    "Dynamic range or light sensitivity range of a sensor indicates the ratio of light exposure between the highest brightness a camera can capture (saturation) and the lowest brightness it can effectively capture (typically when noise becomes more important than signal, i.e., SNR < 0 dB). This range indicates the maximum contrast that can be effectively captured by the sensor. The larger the dynamic range, the better, as the sensor is able to capture higher-contrast scenes. Note that dynamic range is expressed on a logarithmic scale in EV (same as f-stop), thus an increase of 1EV corresponds to a doubling of dynamic range." - DXO Labs

    DSLR's are in the 11-12EV range.
     
  3. Dwig

    Dwig TPF Noob!

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    Exactly, and they all have their greatest dynamic range at their lowest ISO. If you need to squeeze the most out of your digital camera use only the lowest ISO. Check out the reports at DXO Labs' DXOmark site:
    Welcome to dxomark.com (beta), a free resource dedicated to RAW-based camera image quality
    and look at how the dynamic range varies with ISO with various cameras. Comparing the older Nikon D70 with a new D700 will show some extremes. Even so, the D70 at ISO 200 beats the D700 when used at ISO 800 and above

    Digital cameras today have roughly the same range as common films. The big difference is the shape of the curve. Digital is pretty much a straight line where each increment in subject brightness results in the same increment in the image whether in the shadows, midtones, or highlights. Film, on the other hand, is very non-linear with shadows and highlights rather compressed. The plots of the relationship between exposure and density for films is called the DlogE curve (Density vs the log of the exposure), though I prefer the old term (H&D curve) that honors the early researchers in this area, Hurter and Driffield.

    see: Sensitometry - Wikipedia, the free encyclopedia
     
  4. Mr. Murmeli

    Mr. Murmeli TPF Noob!

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    Great! Very thorough answers :). Thanks for both of you!
     
  5. GeneralBenson

    GeneralBenson TPF Noob!

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    I thought most dslrs were in the 5-6 EV range? 11-12 stop of light is HDR territory.
     
  6. Dwig

    Dwig TPF Noob!

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    DXOmark pegs the old Nikon D70 (a good benchmark model for producing a minimum quality image, most new DSLRs are as good or better) indicates a dynamic range of 10 stops at ISO200.

    A 5-6 EV range is more like the typical clipped in camera JPEG convertion that results with many camera's default settings. Its less than what the camera is actually capable of.
     

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