Lens hood

What is the purpose of a lens hood and why the odd shape

On Sep 12, 7:45 am, Denis <denisphe...@gmail.com> wrote:
> What is the purpose of a lens hood and why the odd shape

Not all lens hoods have the weird shape. More on that later.

When direct sunlight impinges on the front of the lens, it leads to
artifacts called ghosts and flare, which reduce contrast of the
image. Even multicoated lens surfaces always reflect SOME light. And
interior parts of the lens and camera, in spite of being blackened,
still reflect a few per cent. Since the sun is far brighter than any
light source in the scene, sunlight bouncing around inside the camera
eventually gets to the image chip. The more complex the lens (the
more elements/surfaces) the worse flare (and ghosts) become. So the
lens hood is a way to keep sunlight off the lens front when you are
shooting with the sun to the side or in front of you.

In order to keep sunlight off the lens with short focus (wide field of
view) and zoom lenses, the shade would have to be VERY large, larger
than many consider convenient.

The fancy petal shaped sunshades allow you to have a reasonable
sunshade that is useful for wider FOV images, though they do not work
as well as a real, full size sunshade.