Dynamic range best at lower ISO : help me understand

Started 2 months ago | Questions thread
knickerhawk Veteran Member • Posts: 6,954
Re: Dynamic range best at lower ISO : help me understand

jrtrent wrote:

Iliah Borg wrote:

knickerhawk wrote:

David1961 wrote:

It would only be too dark if your objective is producing an OOC JPEG (that's what I mean by referring to prioritized image lightness output). How light/dark it is in-camera is irrelevant if your goal is prioritizing an optimal raw output and you prioritize protecting important highlights that were actually or potentially clipped because of the extra lightening boost that came with the ISO boost. With raw, the goal should be to deliver the most useful data to the converter so that you have the greatest flexibility to determine how to output that data within the DR and color space constraints of your ultimate output medium.

The only valid reason to use ISO as the means for increasing shutter speed is because you're prioritizing the maintenance of the given image lightness over any possible increased highlight clipping.

Not true.

Sigh. We've already gone round and round on this. I really don't want to see another thread go off the tracks. I've done as much as I can to explain to you what my "opinion" on this topic is. I'll let others pick up the baton and continue, if they're so inclined.

The idea that ISO rating is input sensitivity is so rooted that it will probably never go away completely. Even if a person can explain what ISO rating is, his way of thinking about exposure in practice is not fully in-line with his theoretical knowledge.

I've seen it explained dozens of times at this site, either directly to me or just reading other posts on the topic, and I still can't get my head around ISO being anything other than sensitivity. The ISO setting tells me how much exposure I need to achieve a given image brightness. Just like the sunny f/16 rule tells us.

Direct sun on a bright, sunny day means 1/100 second at f/16 for ISO 100; 1/400 second at f/16 for ISO 400.

I know you haven't liked it in the past, but Nikon's explanation still makes sense to me:

"Photography is built on the three pillars of exposure: shutter speed, aperture and sensitivity. Shutter and aperture are controls for adjusting how much light comes into the camera. . . How much light is needed is determined by the sensitivity of the medium used. That was as true for glass plates as it is for film, and now digital sensors. Over the years that sensitivity has been expressed in various ways, most recently as ASA and now ISO." https://www.nikonusa.com/en/learn-and-explore/a/tips-and-techniques/understanding-iso-sensitivity.html

That article also tells me that "raising the ISO means . . . an increase in what's called noise," a relationship I can confirm has been true with every digital camera I've owned.

And I can confirm that what you saw with every single digital camera is a correlation between raising ISO and the increase in noise. That is NOT the same thing as saying that it's ISO that caused the increase in noise. In fact, it was the decrease in exposure (shutter speed and aperture) that was also correlated with the increase in ISO that was the real cause of the increase in noise. If you haven't yet absorbed this distinction, then erroneous marketing department fluff pieces like the Nikon one you reference will continue to make sense even though they're dead wrong.

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