Getting my head around EV adjustment

[sunshinewelly]

I am trying to get into pro mode with my drone and have been using the filters and trying to lock the shutter speed to 2x frame rate etc

Trying where possible to keep iso around 100

What I can't work out though is what does the EV setting do. It changes the zebra exposure warning but actual changes is it making to the camera settings etc

 

[Meta4]

What I can't work out though is what does the EV setting do. It changes the zebra exposure warning but actual changes is it making to the camera settings etc

If you are using manual settings, EV is an indication, not a setting.
It's indicating how the brightness of the scene compares with the exposure settings you've made.

If the camera's meter agrees with you and would use the same exposure setting, it would show EV0
If the scene was 1 stop brighter than appropriate for the settings you've made, it would show EV+1.0 etc.

If you use automated exposure settings, you can use exposure compensation to adjust the camera to over- or underexpose above or below what the camera's meter would have used, by a specified amount.
eg You could set the camera to underexpose by 0.3 stops by dialing in EV-0.3.

 

[zocalo]

I am trying to get into pro mode with my drone and have been using the filters and trying to lock the shutter speed to 2x frame rate etc

Trying where possible to keep iso around 100

What I can't work out though is what does the EV setting do. It changes the zebra exposure warning but actual changes is it making to the camera settings etc

EV is technically a scale of scene brightness, but at a simplistic level most typical scenes will average out to about 18% grey (which appears darker than you might think). Cameras use that assumption to try and estimate a "correct" exposure that will give a good balance between dark shadows and blown highlights, although more recently that has been supplemented by more intelligence in recognizing what the scene is and apply a more educated guess. EV adjustment lets you correct for that when you are dealing with a very bright scene (e.g, snow) or very dark scene (e.g. a nightime street) to give a more accurate image in-camera. Generally, it will do that by adjusting either the exposure or aperture, depending on the shooting mode.

EV compensation basically lets you bias the camera by a preset value so that it will adjust the exposure by a given amount to correct for that difference. In the two examples above, dialing in some positive exposure compentation will help make snow appear white rather than grey, and negative exposure compensation will help avoid a nighttime scene appearing too bright. There are technical approaches and various charts to do this, but you really only need a little experience to make a guess that's good enough, and in the meantime the following will usually avoid any especially serious exposure issues:

Dark street scene, limited street lights: -2 stops of EV
Dark street scene, lots of lights: -1 stops of EV
Normal landscape conditions (likely ~18% grey) - no compensation
Snowy landscape, dull light: +1 stops of EV
Snowy landscape, bright sun: +2 stops of EV

Keep in mind though that there isn't really a "correct" exposure for a given scene, only for what the photographer was hoping to achieve when they captured it.

 

[EsaT]

Indeed EV itself is very old photography term meaning exposure value, which was huge deal in fully manual photography era.

Exposure value - Wikipedia

en.wikipedia.org

But in modern automatic camera era it's been demoted and is used in relation to exposure compensation from that calculated by camera automatics.
+1 EV means one stop more light, which can be achieved by either doubling ISO value, doubling exposure time (50% slower shutter speed) or one stop bigger aperture.
Again -1EV means one stop less light.

In case of fixed aperture camera like Air 2S, you can't adjust exposure by changing aperture and can only lower exposure (per time) by using ND filters.
Whose number tells what part of light it lets through:
ND2 halves the light and is equal to one EV/stop difference
ND4 drops light to quarter and is equal to two stops.
ND8 is third stop down, followed by ND16 etc.

Same limit applies when you want to use certain shutter speed to blur/soften fast motion in video. (whose fps is too low for motion speed)


Other direction is lot harder if you've already removed filters, aperture is maxed and shutter speed can't be slowed down anymore.
In those situations you simply need to increase ISO to maintain image brightness.

 

[sunshinewelly]

cheers