J1 lightmeter calibration - ~3.3eV of highlight headroom.
I've used Rawdiger to calibrate lightmeter in my J1. An executive summary: there seems to be approximately 3.3 stops of headlight room in green channel.
The gory details can be found at http://stasvolik.net23.net/J1_Lightmeter.html .
To make a long story short, here are the graphs for the cloudy daylight:
For the incandescent (halogen) lighting:
Special thanks to Iliah Borg and Alex Tutubalin for this tools and for helping me to figure out how to do the job right.