This software was created to help you to configure the approximate value for the Light Value (LV), Exposure Value (EV), shutter speed, ISO and aperture.In photography, exposure value (EV) denotes all combinations of a camera’s shutter speed and relative aperture that give the same exposure.How to use itWith your touch or keypad down/up, you move de ruler.Establish the brightness (EV) of your subject, using either your hand-held light meter or the descriptions on the calculator. (Note that the descriptions are only a guideline – if you’re working from them you may wish to bracket your exposures.)Slide the sliding scale so that the ISO value of your film lines up with the appropriate EV value. Then you can read off aperture/shutter speed combinations from the lower pair of scales.This version of the calculator is reversible. Use the side with EVs 8-16 for bright conditions, and the 3-11 side for dim light.