What does " Meter: 13.9 EV" mean?

Started Oct 18, 2005 | Discussions
JohnK Veteran Member • Posts: 7,169
What does " Meter: 13.9 EV" mean?

While looking at Phil's gallery of preproduction R1 photos I see that for each photo he lists the camera information, such as this, for photograph #13, "Info: Focal len: 32 mm, Shutter: 1/400 sec, Aperture: F8, Meter: 13.9 EV, ISO 160". I understand all the terms therein, except "Meter: 13.9 EV". I'm used to thinking of EV in terms of plus or minus two or three, but 13.9 EV has got me stumped. Would someone kindly explain Meter: 13.9 EV?
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SMC2002 Veteran Member • Posts: 3,357
Re: What does " Meter: 13.9 EV" mean?

Hiya John,

From the settings used, the "EV" values equate perfectly with the chart, which also gives foot candle and lux equivilants, at the bottom of this webpage.

http://www.fredparker.com/ultexp1.htm

Steve

chris33 Contributing Member • Posts: 642
Re: What does " Meter: 13.9 EV" mean?

GREAt info Steve! Many thanks!

Chris
--------

SMC2002 wrote:

Hiya John,
From the settings used, the "EV" values equate perfectly with the
chart, which also gives foot candle and lux equivilants, at the
bottom of this webpage.

http://www.fredparker.com/ultexp1.htm

Steve

Doug Kerr Forum Pro • Posts: 20,899
Ev (exposure value) designates exposure

Hi, Jihn,

JohnK wrote:

While looking at Phil's gallery of preproduction R1 photos I see
that for each photo he lists the camera information, such as this,
for photograph #13, "Info: Focal len: 32 mm, Shutter: 1/400 sec,
Aperture: F8, Meter: 13.9 EV, ISO 160". I understand all the terms
therein, except "Meter: 13.9 EV". I'm used to thinking of EV in
terms of plus or minus two or three, but 13.9 EV has got me
stumped. Would someone kindly explain Meter: 13.9 EV?

Ev ("exposure value") is the APEX (logarithmic) designation of exposure. It reflects the combined effect of the shutter speed and aperture.

A shutter speed of 1/400 sec and an aperture of f/8 together represents an Ev of 14.6. That is 2/3 stop less exposure than Ev 13.9 (a larger Ev represents a lesser exposure.).

I'm not sure that the "meter" Ev actually means. It could be that the meter, left to its own devices, would have called for an exposure of Ev 13.9 but that exposure compensation (the value you associate with "Ev" notation) was set to -2/3, which would cause the camera to actually use for the shot an exposure 2/3 stops lower than the metering system was inclined to use (that is, Ev 14.6).

The APEX system of notation is discussed in detail in my tutorial article, "APEX - The Additive System of Photographic Exposure", available here:

http://doug.kerr.home.att.net/pumpkin/index.htm#APEX

Best regards,

Doug

Visit The Pumpkin, a library of my technical articles on photography, optics, and other topics:

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imbsysop Veteran Member • Posts: 4,963
Re: What does " Meter: 13.9 EV" mean?

tis very forum will tell you ..
http://www.dpreview.com/learn/?/Glossary/Exposure/Exposure_01.htm

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