Exposure Calculator — Sunny 16 Rule, EV Chart & ND Filter ToolExposureCalculator

The exposure triangle describes the relationship between ISO, aperture, and shutter speed. These three settings control how much light reaches the sensor. Changing one requires adjusting at least one of the others to maintain the same exposure level. ISO controls sensor sensitivity, aperture controls the size of the lens opening, and shutter speed controls how long the sensor is exposed to light.

Exposure Value (EV) is a single number that represents a combination of aperture and shutter speed at a given ISO. EV 0 equals f/1.0 at 1 second at ISO 100. Each increment of 1 EV halves the amount of light (one stop brighter scene). Typical daylight scenes range from EV 12 to EV 16. The formula is EV = log2(N² / t), where N is the f-number and t is the shutter time in seconds.

ND (Neutral Density) filters reduce the amount of light entering the lens without affecting color. Each stop of ND doubles the required shutter speed. For example, an ND64 filter (6 stops) turns a 1/250s shutter speed into 1/4s, enabling motion blur or wider apertures in bright conditions. They are essential for cinematographers who need to maintain a 180-degree shutter angle in daylight.

The Sunny 16 rule is a quick exposure estimation method: on a sunny day, set your aperture to f/16 and your shutter speed to 1/ISO. For example, at ISO 200, use f/16 and 1/200s. For overcast conditions, open up to f/8; for shade, use f/5.6. This rule has been used by photographers since before light meters were common and remains a reliable starting point.

An ND1000 filter is a 10-stop neutral density filter. It reduces light by a factor of 1024 (approximately 1000). A 1/500s exposure becomes roughly 2 seconds with an ND1000. These are commonly used for long exposure photography of waterfalls, clouds, and crowded scenes where you want to smooth out movement.

Multiply your current shutter speed (in seconds) by the ND filter factor. For example, with a 1/125s shutter speed and an ND8 filter (3 stops, factor 8): (1/125) × 8 = 1/15.6s, approximately 1/15s. Alternatively, double the shutter time for each stop of ND filtration. Our ND filter calculator above does this math instantly.

For shooting video at 24fps with a 180° shutter (1/48s) and f/2.8 at ISO 100 in bright daylight (EV 15), you need about 6 stops of ND filtration (ND64). For wider apertures like f/1.4, you may need an ND128 or ND256 (7-8 stops). Variable ND filters (ND2-ND400) are convenient for run-and-gun shooting where lighting changes frequently.

Golden hour (about 1 hour after sunrise or before sunset) is roughly EV 10-12. At ISO 100, good starting points are f/2.8 at 1/125s, f/4 at 1/60s, or f/5.6 at 1/30s. For video at 24fps with 180° shutter (1/48s), use ISO 200-400 at f/2.8-4. The warm color temperature (around 3500-4500K) is what makes golden hour so appealing for filmmaking.

When your subject is backlit, the camera's meter will underexpose the subject by 1.5-3 stops. Compensate by opening up 1.5-2 stops from the metered reading. For example, if the meter suggests f/8 at 1/250s, try f/4 at 1/250s or f/5.6 at 1/125s. Alternatively, spot-meter on the subject's face and expose for that reading. A reflector or fill light can balance the exposure ratio.