Choose a place (or use your location) and a date. You get the times of the soft golden light, the blue hour, sunrise and sunset, and the height of the sun all day.
Golden hour: the sun between 6° above and 4° below the horizon, warm and soft. Blue hour: the sun 4° to 6° below the horizon, deep blue sky with lights still on.
Times are worked out with the standard astronomical formulas; mountains, buildings and clouds can change what you see by a few minutes.
Change one setting and see what the others must do: equivalent exposures and the EV.
ND filter & timerYour new shutter time with 1 to 20 stops of ND, and a countdown for bulb mode.
Stars without trails (NPF)The longest exposure for pin-sharp stars, by the NPF rule and the old 500 rule.
Flash guide numberGuide number, distance or aperture for your flash, with ISO and partial power.