Luminance or Illuminance ?

Started Mar 28, 2013 | Discussions thread
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GeorgianBay1939 Veteran Member • Posts: 4,044
Luminance or Illuminance ?

For my personal use I am writing a note on how I use my GH2 to ETTR (sometimes whilst bracketing) a scene using the camera's spot meter.
 My hands and eyes know what I am doing but my maturing brain is well challenged.
Last fall I decided to replace the potentially misleading terms in popular photography with more accurate ones.
See why:
A while ago I started using the term Luminance Range of a scene to replace DR in my own thinking.   I thought that I had the correct term.  But now I am not so sure.
I use the camera's spot (exposure) meter to "look" at a scene with the histogram showing in the EVF and play with the half-press.   I think that I am surveying the Range of Luminance in the scene.  But I might be surveying the Range of Illuminance.  Both are (light) energy per area.  
Obviously what I am measuring (off of the sensor in the GH2) is also affected by the f/ (more accurately the T) of the lens.  I am NOT so worried about that.
I am trying to get at the notion that what "loads" (energizes) the sensor is determined by
the Luminance/Illuminance of various parts of the scene
the f/ (T) of the lens, and
the SS (the length of time that the shutter is open)
Luminance?  Illuminance?  ______________?
Thanks for your help.  

 GeorgianBay1939's gear list:GeorgianBay1939's gear list
Panasonic FZ1000 Panasonic Lumix DMC-GH2 Panasonic Lumix DMC-GX7 Panasonic Lumix DMC-GH4 Panasonic Lumix G Vario 7-14mm F4 ASPH +10 more
Panasonic Lumix DMC-GH2
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