eli5 / why are zoomed lights in movies composed of octagons?


I mean..in movies when there are a lot zoomed lights, like car lights, street lights or similar they all looks like octagons. Do you know why?

In: 1

It’s called “bokeh” and it’s the shape of the lens that you’re seeing – or, more accurately, the shape of the shutter that closes inside it. They come in all different shapes, depending on the lens – even triangles!

It’s because of the shape of the aperture blades in the lens different lenses can have different amounts of blades which changes the bokeh.

For fun you can put paper with shapes cut out over a lens to make different shapes in the out of focus lights.

This is caused by the shape of the aperture (not the shutter)

The aperture is a hole in the lens through which the light passes to get to the film or sensor. The aperture can open or close to control the amount of light that passes through in a given amount of time, with a bunch of other side effects (the one folks are usually most interested in is the depth of field, which is the distance between the where something is too close to be in focus and where something is too far to be in focus)

It’s called “bokeh” and occurs for things that are out of focus (usually implying a short-depth-of-field lens, low f-number, usually a lens that’s physically big compared to the sensor – and they use huge lenses in film-production).

The shape of the bokeh effect depends on the shape of the aperture in the camera.