Tag EffectiveLV - Values

[dosdan]

Edit:  I found a post in the Pentax forums which may answer some of your questions.

I wrote the LV calculator referred to in that link. 

An interesting related topic to LV is the old APEX system. I've explained it here:
http://www.pentaxforums.com/forums/photography-articles/126203-stops-shutter-speed-aperture-iso-sensitivity.html#post1717721

Exif 2.3 already contains APEX data which can be used, with a bit of mental arithmetic, to work out LV:
http://www.pentaxforums.com/forums/photography-articles/126203-stops-shutter-speed-aperture-iso-sensitivity.html#post1721119

Dan.