In detail:

An important exception in the German drone law applies to model airfields. There only the marking of the drone is mandatory. Other regulations such as the maximum flight altitude etc. do not exist on such airfields. In addition to police and rescue services, there are various places where flying is prohibited: in residential areas, industrial plants, constitutional bodies, federal and state authorities, prisons and on certain traffic routes (especially motorways and railways). The law is very inaccurate when it comes to exact distances. For prisons, a distance of 100 m is given, which apparently also applies to the other buildings in this category. For airfields there is also no exact distance prescribed. However, since in most countries the standard is 5 km, this can be taken as a good guideline. It is also true in Germany that the owner of the drone has the responsibility to avoid the aircraft or helicopters. One should also check whether the chosen insurance covers the use of the drone, if this is not the case, flying is not allowed. Flying at night is prohibited without exception. The law also mentions video glasses. These can be used by drone pilots to see the drone image directly in front of them (similar to virtual reality glasses). These are permitted as long as a second person is present who has visual contact with the drone and can point out any problems to the pilot.

For a simple overview of the laws before take-off, the BMVI flyer is helpful (translated to english by me).

Exceptions:

If you want to fly near an airfield or other forbidden zones, you have to ask the responsible persons. On the website of the Federal Supervisory Office for Air Navigation Services you will find various maps with prohibited zones and contact persons, as well as application forms for exceptions.