Panasonic Extended ISO Highlight Recovery in ACR

G7 Highlight recovery, Extended ISO 100, ACR 9.1.1  The pretty magenta/pink color is entirely an unwanted artefact.

Many Panasonic Lumix  cameras have a regular ISO range with the option to select [Extended ISO] in the Rec Menu.

Model	Regular minimum ISO	Lowest with Extended ISO
G7	200	100
LX100	200	100
FZ1000	125	80

For reasons beyond my comprehension low extended ISO settings can cause problems with image integrity if highlight recovery in Adobe Camera Raw is utilised.

I tested three cameras for this today. The test consisted of applying plus exposure compensation in 0.3 EV step increments until the image was obviously very overexposed in the EVF and monitor.

In Adobe Camera Raw 9.1.1 I dragged the Exposure and Highlights sliders to the left for a best subjective result.

Results

G7 Same amount of highlight recovery as the top photo, ISO 200

G7    

* At ISO 200 the camera handled +3 EV steps of overexposure very well. With highlight recovery a good result was achieved.

* At ISO 100 the +2.66 EV image went a bright magenta/pink color when highlights were recovered.

LX100  Extended ISO 100  Loss of detail with highlight recovery

LX100 Highlight recovery with ISO 200

LX100

* At ISO 200 the camera handled EV+2.66 steps with no problems. Recovered highlights looked good with no color cast or other problems.

* At ISO 100 there was no color cast but the amount of detail able to be recovered was markedly reduced.

FZ1000

* At ISO 125 highlight recovery from +2.0 stops gave no problems.

* At ISO 125 highlight recovery from +2.3 stops gave a slight blue color cast.

* At ISO 80 and +2.0 EV there was a small amount of magenta/blue color shift after highlight recovery.

Conclusion

For general photography with each of these three cameras I do not use Extended [low] ISO settings.

For special situations where I know there is limited subject brightness range and highlight recovery will not be required and I want absolute maximum resolution, I set the minimum Extended [low] ISO available.

Auto ISO does not utilise the Extended Low ISO settings.

Overall the two cameras with a 21.5mm sensor (although that of the LX100 is cropped to 19.2mm) allowed slightly more highlight recovery than the FZ1000 with the 15.9mm sensor.