[Usual disclaimer ... I hope this is not replicating info, but have not been able to find relevant thread elsewhere].

These questions can easily apply to other digital Panasonic lenses, but I have the 14-140 ... ( So, weigh in with other lenses if you like)

• Is there an OFFICIAL figure on actual light loss through the 14-140? (i.e. T stop correction factor?)
• Is the lens callibrated to F-stops or T-stops? (i.e. what are we actually setting "in-camera"?)
• What method do people recommend for DIY verification of light loss, on Pana or manual lenses?
  (e.g. spot meter on through back of lens onto grey card? waveform and grey card somehow? other???)
• Could the "known issue" of the GH2 under-exposing by 2/3 stop be (partially?) explained by it failing (or attempting?) to compensate for the T-stop light loss factor? ... Or does the metering system work around this somehow? (I guess this could be verified by comparing the light loss and resulting under-exposure factor on Pana prime v. Pana zoom but I don't have primes). I read somewhere that the GH2 is callibrated for 40% grey not 50% grey, but I am not sure how this interacts with the T-stop issue. Maybe the 40% and T-stop issue compound each other giving the -2/3 stop result???

Hope to hear from you, oh learned GH2 tribe ....

Cheers!