Zeiss Ikon Nettar 515/16 was a folding, 120 film (6x6 format) camera made in Germany. The model was initially introduced in 1937 and continued during WWII. After the war the production continued from 1948 to around 1951 using different lens and shutter combinations. The camera shown here was made after the war and uses a Vario shutter with Novar 1:6,3 F= 7.5cm lens.
The camera takes square (6x6) photos, so it doesn't matter if you hold it vertically or horizontally. There is a folding viewfinder on the top, which helps you to compose your image.
To take a photo you first need to advance the film (there is a red window on the back which reveals the frame counter), then you cock the shutter and press the shutter release button. You always need to advance the film before taking each photo unless you want double exposures. Using cable release can be useful, especially if you are making long exposures with "B".
You can use a tripod with Nettar 515/16, but you will need a 3/8'' to 1/4'' screw adaptor, because the camera has the older screw type (3/8''). The camera also has a flash sync socket.
Using the camera is rather easy. Avoid using high ISO film because the shutter speeds are a bit low for modern standards. As with all cameras with bellows, before using, it is important to check the bellows for holes. If there are holes (even little ones) your photos will result with light leaks, or in cases where there are big holes, your film will be ruined. To check the bellows for holes, open the back and extend the bellows in a dark room. Insert a flashlight from within and if there are any pinholes you'll be able to see them by looking at the camera from the outside, while moving the torch around the interior.