FX/Z1 rated 9 Lux at telephoto setting
 

Here's explanation of 6 Lux Japanese rating. The camera rated 3 lux at F1.6. End telephoto range is F2.8, which means about 9 Lux. You get 6 Lux average. This explains why Canon and other makers have higher lux numbers in Japan. The Japanese ratings are lot more honest.

Did anyone check F-stops/lux ratings at various focal lengths?

I believe the difference is that the Japanses require a signal level of 100IRE (at max gain) while the USA requires a signal level of 50IRE (at max gain).

In both cases, the WIDE setting is used.

A far more professional spec is lux at F-stop with NO gain. I believe this is a 100IRE level.

Without a signal-to-noise ratio, I fail to see how a lux rating is relevent. Does noise enter into the calculation or not?

-Steve

You cannot compare lux ratings between manufacturers. At this point there is no standard in lux rating comparisons between each other. Sony's lux is different from Panasonic or Canon lux . To make clear: 1 Sony lux does not equal 1 Canon lux or 1 Panasonic lux. They are all different. You can compare the lux rating of cameras within Sony but that's it.

One way to compare cameras is by the relevance of the f-stops and the footcandles associated with a particular f stop, let's say f/11 at 2,000 footcandles. But dont make the assumption that lux rating is standardized. It is not !!!!!

Augusto is quite right. The way the manufacturers have treated lux ratings so differently, it's a spec you can forget. Besides, when in doubt, just add light.

For Steve M. -- great to see you at NAB! Hope to run into you again on your own turf in July for DV Expo East.

Thanks, Chris. However, I reread Radek's posting and realized he was aware of the lux rating discrepancies between manufacturers. My apologies.