Toronto. Do you remember submarine movies? Somewhere in the plot you would hear “down periscope” before a dive alarm sounded. Recently, I was surprised to see the term being used today to refer to a smartphone-sized telephoto lens design,
By using this technique, a lens physically longer than the width of a smartphone can be used. An alternative of a smaller size lens and a smaller sensor instead would cause a deterioration of the image.
You can read about this lens design and why it is needed in today’s world of smartphones. (It is said that a smartphone camera is the most popular in the world today.) The blog, “How-To Geek” published an article by Harry Guinness on August 4th titled, “What Is a Periscope Lens for Smartphone Cameras?. At the bottom of the page that I linked in this post is a paragraph about Harry Guinness including this link to his bio.