Dynamic range best at lower ISO : help me understand

Started 2 months ago | Questions thread
knickerhawk Veteran Member • Posts: 6,957
Re: Dynamic range best at lower ISO : help me understand
1

David1961 wrote:

knickerhawk wrote:

David1961 wrote:

knickerhawk wrote:

David1961 wrote:

knickerhawk wrote:

Photographers get into trouble when they try to straddle both worlds by trying to optimize for lightness output and raw output at the same time (and ISO adjustment is often the specific mechanism that gets them into trouble here).

How will ISO adjustment get them into trouble?

As I explained to you in our last encounter, one way to get into trouble is using ISO to maintain the same lightness level while also using it to force a change in exposure level (i.e., using it while in a priority mode). If based on your scenic conditions and metering choice you're already in the highlight clipping danger zone at base ISO, then raising ISO in aperture or shutter priority mode will likely result in unnecessary clipping - that is, clipping that could have been avoided by using a direct EC adjustment to accomplish the desired exposure adjustment instead of using ISO.

But if in say Aperture priority mode you might need to raise ISO from base, or whatever, to get a fast enough shutter speed to freeze action, obviously while still avoiding clipping highlights and assuming aperture has been set to the largest to give the DOF you want.

Except, as I previously explained to you, you don't need to raise ISO in order to increase shutter speed. You can simply use EC.

But then my image will most likely be too dark and I would have to raise ISO anyway.

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.

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