What if the Dynamic Range discussion on social media is inaccurate?

[Siegfried]

Hi Folks.

I discussed this in my recent articles. I also explained why the exposure triangle is not a complete solution for digital cameras. Take some time and study the included schematic. We control 3 of the exposure equation's variables (shutter, aperture & ISO). It is possible to control four variables. Which one is the 4th, and how do we control it? Think of reflected light (luminance) and using a flash.

The DR discussion on social media is inaccurate in most cases. Saying the ISO adjusts sensor sensitivity is false. The sensor's sensitivity is set at the factory. The ISO function adjusts image brightness.

Do the following experiment with these steps:

- Select ISO800 and A-Mode (aperture mode). It's better to use a tripod for this.
- Set the camera up for a typical landscape with clouds (use a 12 or 14mm M43 lens)
- Point the camera up/down until you have a small amount of clipping in the clouds.
- The histogram will be to the right (ETTR). (the histogram will show the clipping)
- Write down the exposure settings, select M-Mode, and enter those settings...
- Turn the ISO to 200 (the clipped highlights should disappear) and record the image
- Open the raw file in Workspace and increase the EC until the brightness is OK. (with no clipping)
- Use the different tonal adjustments (gradation, highlights/shadows, tone curve) to fine-tune your image...
- In most cases, you need less than a stop lower ISO to recover the blown highlights in the camera
- Would you use the ISO Low option? In other words, apply ETTR at ISO200 and go back to Low...

Why does this technique work? Because the ISO function is one of the three exposure variables, the ISO adjusts image brightness, and the sensor stays saturated throughout the experiment. That means I did not recover blown highlights. I reduced the image brightness with the ISO function and corrected it again in WS. Try the inverse by taking the same image at ISO800 and reducing the brightness in WS. Why? Because the ISO and Exposure Compensation (EC) in Workspace do the same thing (amplifying the image signal).

That said, it is possible to clip the sensor. How will we know that, and how would one control/manage the sensor?

This example illustrates the importance of accurate information and knowledge...

Best

Siegfried


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I took the image with the EM5 II and the 12-45mm f4. I saturated the sensor at ISO200, dropped the ISO to 100 (low), and corrected the brightness in Workspace... Go to my Fuji color and FX-Blue chrome article for an illustration of the Workspace editing pallet. I organized the WS editing pallet to follow the image signal path in the above schematic. This simplifies the raw conversion sequence in WS.

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