Exposure calculator

This web-app will guide you step by step through the estimation of the right exposure for hemispherical photography (and also for normal photography). You can open or close each box by clicking on its title.

You can choose between 2 modes: normal photography and hemispherical photography. In normal photography, the exposure value (EV) is calculated for the whole picture, but in hemispherical photography it is estimated for the sky only, then applied with an offset of -1.
Four different ways to get the exposure are proposed. First you can obtain a measurement by using a spotmeter and entering the value directly. Second, you can estimate EV from the ambient light conditions. Third, you can use any camera and look at the ISO sensitivity, aperture (F number) and speed that this camera uses in automatic mode. Finally, it is also possible to use the EXIF metadata, i.e. data stored within a picture that you have taken, either with the device on which you use this web-app or with another camera. Note that some cell phone cameras do not save all necessary data, in which case "NaN" (not a number) will be displayed and no EV will be calculated.
The lowest field of this web-app lets you change individually the ISO sensitivity, the aperture and the speed, always adapting the other settings so that they match to the target EV.

target EV	sensitivity ISO	aperture F/A	speed 1/s