The Milky Way has fascinated humanity for thousands of years and is the galaxy in which our solar system and Earth are located.
It itself is estimated to consist of around 100-300 billion stars. It has a diameter of approximately 170,000 - 200,000 light years and an approximate thickness of up to 15,000 light years with bulge.
It stretches 360 degrees across our night sky and is seen by us as a bright band. Because of its band, which appears as a whitish veil to the naked eye, it is called the “Milky Way”. We perceive it this way with the naked eye because we cannot see individual stars, but only an enormous number of many faint stars in the galactic disk and the galactic center. If we photograph the Milky Way as a 360 degree panorama, it will appear as an arc. When we as photographers talk about the visibility of the Milky Way, we mean the visibility of the galactic center, because this is the part of the Milky Way that is actually interesting to us.
The Milky Way is basically visible all year round. In the northern hemisphere, however, we can only see the galactic center between the months of March and October. Between October and March it lies below the horizon and is therefore not visible to us. In the northern hemisphere, the galactic center is always close to the horizon, while in the southern hemisphere it is the other way around which means it is visible towards the zenith. The Southern Hemisphere is therefore better suited for Milky Way photography if you want to photograph the galactic center in isolation or want to highlight it more clearly.
The further south you are, the better the Milky Way is visible; it can be seen best from a latitude of around 50 degrees north. To be able to photograph the Milky Way well, you should look for a place that has as little light pollution as possible and it should be a new moon night or a night when the moon is not up at the time when you can see the galactic center.
The moon would shine so brightly that it would illuminate / outshine the stars and they would not be visible. Ideally, you should choose a suitable location during the day so that you can then be well prepared for Milky Way photography at night. In our area it is not always easy to see the Milky Way with the naked eye straight away, as there is practically no area with minimal light pollution, as even a small village many kilometers away can still provide enough light pollution on the horizon.
Basically, the larger a place or city is, the further away it has to be in order to be able to photograph the Milky Way. In spring, the galactic center is only visible shortly before sunrise and is located east to southeast in the sky. Towards early summer, the Milky Way can be seen in the south-southeast direction, it rises earlier and earlier and is visible for longer. In the summer it is no longer as flat above the horizon as it is in spring, it is actually practically vertical and can be seen in the south almost all night long.
In autumn you can see the galactic center in the south-southwest direction directly after sunset, the visible time becomes increasingly shorter before it disappears below the horizon again from November to March.
As far as camera settings for Milky Way photography are concerned, as with night photography, you should choose a very light sensitive wide-angle or ultra-wide-angle lens with an aperture of f2.8 or smaller. The ISO should be set at 3,200 to 6,400 depending on the darkness and noise behavior of the camera.
The exposure time for a full-format camera with a full-format lens at 16mm focal length with an aperture of f2.8 and an ISO of 3,200 is a maximum of 20 seconds so that no star trails appear and the stars can still be seen as sharp points. For an APS-C sensor and all non-full-frame cameras, the so-called crop factor must be calculated, which indicates the exact exposure time that can be selected as a maximum without getting star trails. The crop factor can be calculated by dividing the length of the 35mm format by the length of the image sensor.
The crop factor describes the ratio with which the image is cropped and the factor with which the focal length is extended.
You can find simple tables on the internet to find the right value for the corresponding camera and lens.
A further technical explanation of the details would be too scientific and too long at this point.