Simple Exposure Calculator

Lens Aperture Value
f / f / stop

Shutter Exposure Time
second(s)

Sensor Sensitivity
ISO

Exposure Value
EV₁₀₀ =

Lock

Round to nearest third-stop.

How to use:

Enter the camera settings for a known exposure.

Lock the exposure.

Tweak indivdual settings, watch the others adjust to keep exposure consistent.

Use keyboard shortcuts to get around quicker: A, T, S, L, ↑, ↓.

Information:

EV = log₂(N² / t) where N = f-number and t = exposure time in seconds.

EV_S = EV₁₀₀ + log₂(S / 100) where S = desired ISO.

I wrote this tool to plan long exposures outside my camera's typical range.

Get more background on exposure and camera settings from Fred Parker.
Useful wikipedia articles:

Advanced Exposure Calculator

A Tool To Calculate The Camera Settings For Exposure. Enter Three Values, The Fourth Will Be Calculated. Aperture, ISO / ASA And Shutter Exposure Time Can Be Set At The Camera. EV Means Exposure Value. Different Lighting Conditions Require Different EVs, The Brighter, The Higher Is This Value. A Table With Conditions And Their Approximate EVs Is Below The Calculator. You Can Enter Time At H, M, S As Hour, Minutes, Seconds And Then Press ↞ To Convert Into Seconds.

Please Insert 3 Values, The Fourth Will Be Calculated:

Lighting Condition		EV/th>
Full Sunlight, Snow		16
Full Sunlight		14 thru 15
Cloudy		13
Thick Clouds		12
Sunrise / Sunset		12
Dusk / Dawn		5 thru 11
Night, Bright Street		7 thru 8
Inside Buildings, Artificial Light		5 thru 8
Night, Near Lighted Buildings		5
Night, Distant Lighted Buildings		2 thru 3
Night, Dark Landscape At Full Moon		-2
Night, Dark Landscape At Half Moon		-4
Night, Dark Landscape At New Moon		-6 thru -8
Night, Stars		-3 thru -9
Night, Weak Celestial Bodies, Nebulae		-10 and below

The Formula For This Calculation Is:
EV = Log₂ ( 100 * Aperture² / ( ISO * Time ) )

Aperture F-Stop Number (ƒ/):
ISO / ASA Number:
Exposure Value Number:
Shutter Exposure Time Second(s):