What is EV mode

Discussion in 'Lighting Equipment' started by sarah_lange, Jun 6, 2009.

  1. Hi, Could someone explain what EV mode is when using a light meter and how it is different from measuring ambient light using either aperture or shutter priority? I am using a Sekonic L358. Thank you!
  2. EV stands for Exposure Value. It is the combination of aperture and shutter speed (often at ISO100) rolled into one. For instance EV5 @ISO100 means a certain amount of light (80 lux). The exposure could be f/1.4, 1/15s or f/5.6 1s or any other equivalent combination. More about it here: http://en.wikipedia.org/wiki/Exposure_value
  3. Hybrid auto owners refer to Electric Vehicle mode as EV mode as well, which might complicate your search.
  4. On certain cameras (old style Hasselblads for instance) you can set a Exposure-Value and lock it with a button. If you lower the shutterspeed the (cross-locked) aperture will close accordingly. Pretty neat for doing flash-bracketing outdoors for example.
  5. ****An EV of 0 is defined as F1 at 1 second over 1/2 century ago; with NO ie ZERO ties to ASA; DIN or ISO at all.

    An EV of 13 is 1/125 at F8; what many of us used with old Kodachrome II (asa 25) on a bright sunny day.
    Tying a EV of say 10 to an iso of 25 means one is in open shade; tying it to an iso of maybe 200.
    Since the internet many errors have been introduced about EV; many newcomers preach wrongly how it is based on asa/iso 100; when EV has nothing to due with asa or iso; it is an exposure setting; a combo of f stop and shutter speed.

    With bright sun and asa 25 film ;the exposure meter may give out an EV of 13; or 15 for asa/iso 100 film.
    With a 1950's camera; an EV system was a fad on many models; the meter gave out an EV number; then one set the EV ring on the camera; maybe a Retina IIIc. Thus with an EV of 13; one could use 1/125 at F8 for family shots; or 1/250 at F5.6 for sports; maybe 1/30 at F16 with a tripod for alot of DOF with a scenic with a foreground too.

    I mention about the EV not being tied to asa because this is rather a new event in the last decade; trying to rewrite what EV is in the SPIE handbooks.
    If you yell out to set ones 1950's camera to an EV of 13 and it is bright sun; one should of course knwo waht film he has. If its is asa 800 print film; one has a gross overexposure. But to yell out what EV to use using a meter; one has to set the asa/iso dial on the meter first to get an EV number to yell out to another.
    As mentioned before; an EV of 0 is F1 and 1 second; whether one has as 6 microfilm; or 6400 tri-x pushed with eye of newt.

    An EV of 10 is 1/1000 second at F1; no matter what asa or iso is used.
  6. An EV value is a combo of shutter speed and fstop; ie exposure.
    One can used EV values with reflective or incident light meters.
    in older ancient cameras of the 1950's and sometimes later; the shutter speed dial and fstop wer linked togther; thus if one set the camera to an EV of 13; turning the ring/assembly changed the fstop and shutter speed in step; so the combo still had the same EV of say 13.
    When your Sekonic L358 is set to iso 100; it will readout an EV value of -2 to 22.9 according too its specs. A dumb low cost Sekonic leader here only goes from 2 to 19 at an iso setting of 100; it is a simpler meter with an less active meter cell and circuit. A 5 buck self powered 1960's selenium unit here only goes from an EV of 7 to 18; it is a Joni-Mini.
    The EV system should have nothing to do with shutter or aperture priority.
    Is your question about using EV with a flash?; since the meter you have also has a flash mode too?

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