bfitzgerald wrote:Simple if you post linking to DxO I "assume" you have some kind of faith in those measurements.
Allowing for the usual "margin of error" that any test has, DxO clearly show fudged ISO numbers..
Ever since I was a child I have been able to hold multiple ideas in my head at the same time. Therefore, I can accept that with the way DxO does things they can come up with the numbers they do and at the same time I can think and try things and see that in some cases I can find no practical affect for my photography of what they show. And I can accept that both can be right. I can also read about digital ISO such as the article I linked to on dpreview to try and understand a bit more. I assume other people can do these things also.
You wrote a lot, but still didn't answer what practical difference it makes? I am open to being shown that it makes some practical difference to me. I haven't found it yet, but maybe you can convince me.
bfitzgerald wrote:So in summary here is my problem
Do I trust Henry's "unseen" test with a G3 v a OMD-EM5?
I don't care or expect you to trust what I found when I experimented. I make certain assumptions about most of the people I deal with and one of them is that they are reasonably capable of checking lots of things for themselves. Since this whole issue is of such interest to you (based on your multiple posts over a period of more than a year) I am sort of surprised you haven't done any simple experimenting or reading on your own.
As DxO says:
As tests show, the ISO settings reported by camera manufacturers can differ significantly from measured ISO in RAW. This difference stems from design choices, in particular the choice to keep some “headroom” to avoid saturation in the higher exposures to make it possible to recover from blown highlights.