On 10/10/2019 10:42 AM, Wayne Shumaker wrote:
rambling on iso-invariance...
Moose linked to a dpreview article on iso-invariance. I was reviewing what it
says and was questioning....
https://www.dpreview.com/reviews/panasonic-lumix-dmc-zs200-tz200/5
I also linked to a sample.
<http://www.moosemystic.net/Gallery/tech/GX85/GX85Shadows.htm>
. . .
To me this means I can under expose at lower ISO, but if over exposed at higher
ISO, it could blow out highlights - sensor saturation or clipping.
Exactly so.
From a user point of view, I don't see the advantage of cranking the exposure
knob to -3 versus cranking the ISO knob +3 stops.
For the reason above, to avoid clipping. Upping the ISO, with no EV compensation change will just change aperture and/or
shutter speed to give the same exposure. Unless shooting manual.
Other than the exposure knob is more accessible than the ISO knob? and the need
to then post process the exposure setting. Am I missing the point? Perhaps this
changes the way auto-ISO selects ISO when the exposure is at -3? Or changes the
way the camera captures highlights.
In conclusion, iso-invariance has nothing to do with sensor performance or
improvements.
Here, you have missed the point. Some newer sensor systems have vastly improved noise and color accuracy in the shadows.
If I were home, and so inclined, I could do the same thing to a shot of the same subject as above with an older sensor.
With the shadows pulled up that far, they would be very noisy, and the colors would be way off.
If you go back and re-read the comments to my originals posts of this sample, you will find comments on exactly this
major improvement.
DPR wouldn't be talking about ISO invariance if it wasn't something new, the
result of sensor improvements.
One potential use of iso-invariance might be from the difference in how cameras
capture highlights. The sonies tend to preserver the highlights, say, compared
to a nikon which preserves shadows.
Are you talking about JPEGs? Any such difference from Raw files would be the
result of the conversion software.
Up From the Depths Moose
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