Why do I think DR is overrated...

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Erik Kaffehr
Erik Kaffehr Veteran Member • Posts: 5,187
Why do I think DR is overrated...
5

Here is an image shot with my Hasselblad 555/ELD combined with P45+ back. It is an HDR image built from several exposures.

And here is one, processed from a single exposure.

Now, look at some of the darkest parts...

The left part is single exposure and it has a lot of readout noise. The image on the right side simply uses another exposure from the series and avoids readout noise.

Looking at a brighter patch the non HDR image is a bit more noisy. The noise here is mostly 'shot noise' and that would not really be affected by DR.

The camera used here is a Phase One P45+ back. It has low DR by todays standards.

Source The P45+ uses a sensor very similar to the Pentax 645D. Even a modern APS-C camera like the Fujifilm X-T3 would outperform it in DR.

But the P45+ can deliver a nice image and the darks can be pushed quite a lot, see that framed box to the right.

Left side is normal processing, right side pushed shadows.

We can achieve a pretty similar image from a single shot image with a camera having high DR and HDR photography.

But midtones will be noisy, and improving DR doesn't help with that...

Midtones are noisy on non HDR image.

So, having great DR helps keeping the deepest darks somewhat clean, but making use of it means making mid tones noisy.

This is an artificial subject with extreme luminance range, as shown in RawDigger.

This is the bright side ColorChecker, from both images. Noise levels are very simimlar.

This is the dark side ColorChecker, pushed (Exposure = +8) in Photoshop. We can see that the P45+ image is much more noisy in the dark areas. So, high DR essentially means clean darks.

Obviously, if we have clean darks, we can reduce exposure to protect the highlights and push in development to compensate. But, that means that our midtones get more noisy.

So my take in short is:

  • In most cases most cameras have plenty of DR, so DR doesn't play a role.
  • In demanding situations, we can expose for the highlights and push the shadows, but doing that too much, we will get more noise in mid tones, DR does not help with that.
  • In many cases, using HDR is a better option.

Best regards

Erik

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Erik Kaffehr
Website: http://echophoto.dnsalias.net
Magic uses to disappear in controlled experiments…
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Fujifilm X-T3 Pentax 645D
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