Ever since I was interested in the so called "blue hour". Initialial just at normal photographs but increasingly also at panoram-photographs. There is nothing more beautiful but a wonderful blue gradient in the sky with an rest of sun redness that slide into purple. It always cut me to the quick seeing photographs that show a total deep black sky in the background. O.K. - of course it is easier to have the whole night for taking pictures, but...

However the "blue hour" does not take 60 minutes, in fact it just takes 30 till 50 minutes after sunset in our degrees of latitude. This period is called the "civil" dusk or dawn and variates duration according to the variating sun standing in the midsummer and midwinter - between that two turning points the blue hour is obviously shorter. And by the way it is quite evident you can only enjoy the blue hour in cloudless sky!

Certainly the blue hour is not completely predestinated for taking pictures. There are several different phases. Personally, I am particulary interested in last third of the blue hour. So if the dusk after sunset takes 30 minutes, the last third does not take more than 10 minutes. I called that special, period by my own creation, PRT, what means "photo relevant time" and prepared therefor a little tool for calculating named "Sun Position Calculator" that I placed to your disposal. The beginning of the PRT is mostly set in accordance to the point the street lightning is switched on or rather starts shortly after. The switch on of streetlightning is territorial different between 30 and 40 lux remaining daylight. Incidentally the PRT seems to be quite dark for taking pictures, but don't worry, through the time exposure of your camera the sky will be brighten up. The remaining light is enormously amplified by the time exposure, so that it takes 10 seconds by using aperture 10.

It is in the nature of things that these special 10 minutes have to be prearranged very detailed. So it is advantagegous to visit the location in daylight and in this connection you should define the directions. As everyone knows the sunset is in the west and therefor the most beautiful blue gradient is in this direction. In contrast there is no or just a few blue gradient in the east. Therefor it is the best way taking pictures in occidential direction. You should plan the blue gradient more accurate by panorama-photographs, for example by 360°-panoramas you should start and end in the east, so that the blue gradient is centered in the middle or made a golden ratio.

What can you calculate with this tool?

The tool is able to calculate the blue hour all over the world by its location-search. Because the blue hour also exists at the dawn, in this case it is often called "golden hour", this tool calculates the blue hour in the morning before sunrise and in the evening after sunset. Inside this period the PRT (photo relevant time) is respectively calculated. Inside the PRT it is advisable to take pictures because of the wonderful blue gradients in combination with the streetlightning. Furthermore this tool gives some additional informations.

The following informations are placed to your disposial:

As aforementioned this tool calculate the PRT inside the dawn and dusk. Additionell it is possible to calculate further events:

The astronomic dawn: the period with the lowest light that is measurable.

The nautical dawn: this period follows the astronomical dawn and got enough light to see the horizon and still some stars.

The civil dawn: this period follows the nautical dawn and is called "the golden hour" and ends with sunrise. In this time you are able to see some bright planets, e.g. the venus.

Sunrise: shows the moment of sunrising.

According to this morning features this tool also calculate the same periods in the evening. that are the moment of sunsetting, the civil dusk, the nautical dusk and the astronomical dusk.

This tool shows the data of a whole month of the selected location in a table. You are able to change this data into a PDF-Document for printing, saving or sending as mail.

The Blue Hour Tool is a free of charge Joomla component that will develop further! Every Joomla Admin is able to install this tool in a little while into his Homepage.  Download the tool here! You can also download a Guide to our Tool.

Following features are planed for the next version:

-module for frontpage including the actual wether, for instance the concetration of clouds

-the possibility inside the table-module to change into the daily view

-e-mail to a friend

-moon-display

-automatic calculation of the worldwide timezone movement

-monthly outlook import

-I-Phone and PDA optimizing