@HarryChest 24 May 2021 more from that month

The user https://noise.cash/u/Mr.Trenzs posed a question I took a bit too seriously, lol The picture shape depends on the hole that lets light through towards the sensor and the sensor itself. It has nothing to do with the shape of the lense. The lenses are circular, so it is easier to make the mechanism to move them relatively to each other. Now when it comes to astrophotography things get funnier as there is actually no need for a body around the lens as there is virtually no local environment interferance (no light). In most cases there virtually also is no lens, only a spherical mirror acting as focuser to guide the inflow of light to a camera sensor. The sensor is sqare .. Also: you need a black/white camera to take color photos of the night sky. There is a trick involved. But that is another story altogether.