D
Doug Kerr
Guest
I posted this here as there doesn't seem to be good place for general matters of photographic science.
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APEX is the Additive System of Photographic Exposure, a scheme of logarithmic representation of various factors involved in the matter of photographic exposure. We primarily encounter the system today in its quantity Ev, "Exposure Value" (which, unfortunately, we see used improperly about as frequently as we see it used properly).
I have just released to my technical information site, The Pumpkin, an updated issue of my tutorial article, "APEX - the Additive System of Photographic Exposure", available here:
http://doug.kerr.home.att.net/pumpkin/index.htm#APEX
The new issue includes some new information on the history of the system, and makes a number of editorial improvements.
A significant change is that the article now includes the appropriate APEX quantity for incident light illuminance, Incident Light Value (Iv). Previously, I had in this role the quantity Light Value (Lv), which I had (incorrectly) believed was a modern replacement for Iv.
Further research shows that this change never happened. Instead, it turns out that Lv is a quantity unofficially coined by persons unknown to "rehabilitate" a common incorrect usage of the quantity "Ev".
*****************
APEX is the Additive System of Photographic Exposure, a scheme of logarithmic representation of various factors involved in the matter of photographic exposure. We primarily encounter the system today in its quantity Ev, "Exposure Value" (which, unfortunately, we see used improperly about as frequently as we see it used properly).
I have just released to my technical information site, The Pumpkin, an updated issue of my tutorial article, "APEX - the Additive System of Photographic Exposure", available here:
http://doug.kerr.home.att.net/pumpkin/index.htm#APEX
The new issue includes some new information on the history of the system, and makes a number of editorial improvements.
A significant change is that the article now includes the appropriate APEX quantity for incident light illuminance, Incident Light Value (Iv). Previously, I had in this role the quantity Light Value (Lv), which I had (incorrectly) believed was a modern replacement for Iv.
Further research shows that this change never happened. Instead, it turns out that Lv is a quantity unofficially coined by persons unknown to "rehabilitate" a common incorrect usage of the quantity "Ev".
