Everything About ___
Live briefing

Everything about Light value

In photography, light value has been used to refer to a "light level" for either incident or reflected light, often on a base-2 logarithmic scale. The term does not derive from a published standard, and has had several different meanings:An arbitrary value indicated by an exposure meter such as the Weston Master V, discussed in Adams. This may have been the origin of the term. The indicated light value was transferred to the meter's exposure calculator, which then was used to determine camera settings. Ray (2000) uses the term, with the acronym 'LV', in this sense. The Honeywell/Pentax 1°/21° spot meter indicated in "light level" ("LL"), with LL essentially exposure value (EV) for ISO 100 film speed. The later Pentax Spotmeter V and Digital Spotmeter indicated directly in EV for ISO 100, but they made no mention of "light level", "light value", or LV. A synonym for incident light value, from the Additive system of Photographic EXposure (APEX). Zakia and Stroebel (1993) and Stroebel, Compton, Current, and Zakia (2000) used the term in this sense. They used the APEX symbol , normally used for luminance value. An apparent synonym for luminance value, from APEX. Stroebel, Compton, Current, and Zakia (2000) referred to "scene illuminance" in the text of the article, but the example used units of luminance. The defining equation used the symbol . The table at the end of the article used units of illuminance and the symbol , as noted above. A synonym for exposure value (EV). A synonym for "EV at ISO 100 film speed". This usage appears on many web pages, usually without attribution of an authoritative source. Eads (2000) proposed a revised APEX in which luminance value was equal to EV for ISO 100 speed, but he did not use the term light value. Literally speaking, the English term light value could be translated as "Lichtwert" in German language, however, this is not what the term Lichtwert, as it was introduced by the German shutter manufacturer Friedrich Deckel in 1954 and defined as Belichtungswert in DIN 19010, is used for in German-speaking countries. Instead, the established term Lichtwert describes what became known as exposure value (EV) elsewhere. Wikipedia →

🧭 Start here: a 6-step reading path

  1. Read the overview: Light valueA 5-minute orientation
  2. Skim a recent paper: Dynamics and prognostic value of serum neurofilament light chain in Guillain-Barré syndromeInfluential work since 2022
  3. Pick up a classic book: Regulatory analysis for the resolution of generic issue 94, "additional low-temperature overpressure protection for light-water reactors"The most-reprinted book on the subject
  4. Read the landmark paper: Diagnostic Value of Cerebrospinal Fluid Neurofilament Light Protein in NeurologyCited 742 times
  5. Go sideways: Exposure valueA closely related topic
  6. Go sideways: APEX systemA closely related topic

📖 Definitions

No dictionary entry for this exact phrase.

🗂️ The subject at a glance

No outline available.

🏆 Landmark papers (most cited)

🆕 Influential since 2022

📚 Books worth reading

Ranked by number of editions on Open Library, a rough measure of how lasting a book is.

🔗 Related topics