# 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/22` - small aperture, any lens, typically used with bright sunlight or flash

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: EV11.9

 -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 light moon eclipse to night home interior neon lights to landscape after sunset bright light to weak sun bright daylight to direct sunlight
• Pure Exposure Value: EV100 = `6.92` (based on shutter & aperture)
• Corrected APEX Value: `11.92` (based on shutter, aperture, ISO and ND)
• Luminance: `478 cd/m²` = `44.4 cd/ft²`
• Luminance: `139.4 ftL` (foot Lambert)
• Illuminance: `9554 lux`
• Illuminance: 888 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.