Photography light calculator

The combination of shutter speed, aperture and film speed/ISO (and light modifiers) are expressed as EV or "Exposure Value". This number depends on the amount of light present in a scene, either natural light (sun/moon) or artificial (strobe/lamp). A difference of 1 in EV corresponds to 1 "stop" (+1 stop = 2 x more light). This calculation is valid for both analog and digital photography
A ND (neutral density) filter is a piece of glass you can mount on a lens that attenuates the light without influencing the colors

Camera settings

Aperture: f/5.6 - average aperture, could be cheap kit lens

Shutter: 4 sec - long exposure, needs tripod

ISO: 100 ASA - lowest ISO, very little noise

Neutral Density filter: 5 stop(s) - to allow for bigger aperture and slower shutter speeds in daylight

Scene lighting: EV8

-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
starlight to dim ambient lightmoon eclipse to night home interiorneon lights to landscape after sunsetbright light to weak sunbright daylight to direct sunlight
  • Pure Exposure Value: EV100 = 2.97 (based on shutter & aperture)
  • Corrected APEX Value: 7.97 (based on shutter, aperture, ISO and ND)
  • Luminance: 32 cd/m² = 2.97 cd/ft²
  • Luminance: 9.34 ftL (foot Lambert)
  • Illuminance: 640 lux
  • Illuminance: 59.5 fc (foot-candle)

Explanation

EV is an estimation of how much light you need for a decent photo with these settings. If you use camera settings for EV10 and you actually have EV15 in your scene, your photo will be overexposed. If you use camera settings for EV10 but you only have EV3 light in your scene, your photo will be underexposed.

Examples

Definition of EV: 1s at f/1.0: EV0
Sunny 16 Rule: EV15
Shooting film in broad daylight: EV12
Extreme ISO in e.g. a bar at night: EV0
Long exposure in broad daylight: EV12

References

Exposure value
Scantips: Exposure Value (photography)
The ultimate exposure computer