...
Also, it appears that good choices for ISO when shadow detail matters with the A9 are 100, 640, 1600, 3200, 6400. Am I taking the right lesson from the results?
You may be looking to closely at estimated values.
ISO 100 is where Low Conversion Gain (LCG) starts.
And ISO 640 is where High Conversion Gain (HCG) starts.
Other than that the normal advice applies, use the lowest ISO that you can given your conditions.
If you're shooting ISO Auto I think you might want to simply start at ISO 640.
[bclaff] ISO 100 is where Low Conversion Gain (LCG) starts.
[JF] Sorry, I don't know the operational significance of that.
[bclaff] And ISO 640 is where High Conversion Gain (HCG) starts.
[JF] Does that mean that ISO 640 is better for most purposes than ISOs 500 and 400?
[bclaff] Other than that the normal advice applies, use the lowest ISO that you can given your conditions.
[JF] Not sure how to interpret that. Maybe an example or two would help.
[bclaff] If you're shooting ISO Auto I think you might want to simply start at ISO 640.
[JF] Is what you mean is that ISO Auto should with the A9 be used less often, and instead of ISO Auto it is often better to set the ISO, but at one of the good ISOs, 100, 640, 1600, 3200? Is also what you mean that setting at ISO 500 or 400 is generally a bad choice? If so, that is what I was trying to say.
[JF] I hope I am interpreting the information you're giving us correctly, but I'm happy to be corrected.
Everything that follows is a generalization for typical photography.
There are always exceptions.
The best exposure strategy for any camera is to gather as much light as possible at the base/native ISO setting. (No, I'm not going to demonstrate this with examples.)
Then if the image will be too dark you raise the ISO setting.
Raising the ISO setting when necessary is what ISO Auto does for you.
I think ISO Auto is a great tool and preferable to raising ISO manually.
(My opinion, other disagree.)
Since this is a sensor with dual conversion gain technology there are actually two base/native ISO settings: ISO 100 and ISO 640.
Yes, ISO 640 is about as good as ISO 200-250 (so better than ISO 400 or 500 for sure).
In most situations you would either shoot as ISO 100 without ISO Auto or at ISO 640 with ISO Auto.
(Again, my advice, not everyone takes this approach).
There's nothing special or "good" about ISO 1600 or ISO 3200.
Hope this helps.
even though it's bsi... a while ago the 5d4 got new revised data that shows it to be just a bit behind the a7rii and d810. I find it interesting the a9 also trails behind these sony sensors a bit as it seems now.... Does the a9 have the sony dual pixel patent implemented maybe? It would seem we hit a upper limit for DR in cmos desings?
