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macwest

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    DR has improved by 0.6 stops in ten years

    in Mirrorless Digital Cameras

    Posted

    On 12/5/2023 at 5:20 AM, rodeo_joe1 said:

    The 'dynamic range' - AKA brightness ratio - that can be captured in real life has almost nothing to do with the sensor or electronics of a digital camera, but rather its mechanical construction. 

    It's all about internal reflection of light from the dark chamber of the camera, including the rear of the lens and any additional 'extension tube' that the lens might incorporate. 

    Capturing a 14 stop 'DR' requires a brightness ratio of just over 16,000:1 to actually hit the sensor. And in turn that depends on no more than 0.00625% of the highlight brightness reflecting back into the shadow areas of the picture. 

    Now the best matte black paints or flocking materials in common use have a reflectivity of about 1%, integrated over a 180 degree solid angle. Worse than that at small angles of incidence. While the reflectivity of a digital sensor is probably in the region of 20%.

    So, in order to get only 0.00625% (or less) of the highlights of a scene illuminating the shadow areas, you're effectively asking two surfaces with an aggregate reflectivity of around 0.2% to magically attenuate the highlights by a further factor of 30!? That's a big ask.

    OK; that's a worst case scenario where the shadow area is a tiny percentage of an otherwise bright scene. Which begs the question - "What is an 'average' ratio of highlight to deepest shadow area?" 10%? 20%?

    Even if it's only 5% that still leaves about 50% of the reflected light bouncing around between camera body, lens and sensor to somehow get entirely lost. 

    In conclusion; achieving a 'dynamic range' of more than 14 stops looks like pretty much a wild pipe-dream for the majority of real world scenes. Unless you want to stick to subjects that are nearly all pitch black with only a tiny proportion of highlight area. Maybe the moon on a good dark night and shot with a 24mm lens? 

     

     

    mind blown !

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