Pluto Trigger - Manual (Page 34)

civil sunrise and official sunrise, together with the period between official
sunset and civil sunset, are called civil twilight. The sun is below the horizon,
but its light is visible because it illuminates the upper layers of the
atmosphere. Due to diffused light and different shades of color in the sky,
civil twilight is ideal for portrait and landscape photography.
The sunrise/sunset time is also very useful if you are taking sunrise/sunset
Holy Grail time-lapse. You will need to set the start time of Bulb-Ramping
based on sunrise/sunset time.
For convenience, two countdown clocks are provided to show the
forthcoming sunrise/sunset events.
7.3 ND F
ILTER
ND Filter Calculator is a utility that helps you determine the correct
exposure time/shutter speed when using Neutral Density Filters. Set the filter
you are using and the shutter speed without the filter and the calculator
calculates the new shutter speed with your filter(s) fitted. Press the button
to start the camera exposure.
7.4 S
TARSCAPE
R
ULE
When taking pictures of the sky with stars at night, a long exposure time is
preferred in order to get as much light as possible onto the image sensor of
your camera. However, there is a limit if you are not taking star trail pictures.
To get sharp dot stars, you should not cross this limit. The exposure time limit
is calculated with a formula called Rule of 500.
You select camera model and actual focal length; the slowest shutter
speed is calculated automatically with the crop-factor of your camera
already accounted. Press the button to start the camera exposure.