Light is a simple yet wonderful and sophisticated natural phenomenon. Many great inventions and engineering evolution exist today thanks to the light and its optical properties.
Back in October 2016 I had an amazing opportunity to visit San Francisco, CA. While I was there, I had the chance to see the invention of my favourite artist and engineer, Leonardo da Vinci’s Camera Obscura (literal translation: “dark room” ). All right, let’s not really say it was invented by Da Vinci, as it was already discovered before him. However, as he was into optical engineering, he used Camera Obscura’s principle to study the properties of light. 
|The Giant Camera, CA, USA|
First, the particular design of the camera-like building caught my eyes. A very nice lady greeted me and briefly explained what this building is and what interesting physics can be observed in the dark room The centerpiece is a curved stone plate that functions as a screen. Since it was a very sunny day that day, the image projected on the curved stone plate was life-like. However, it wasn’t just “an image”, it was a live stream motion picture of the ocean waves hitting the rocks that’s right outside of the building.
|The stone plate with the image projection of the rocks outside. Photocredit: ©Bright Bytes Studio |
This Giant Camera is a simple yet astonishing example of the optical applications in nature and art. The principle of projecting the light is through the pinhole onto a big concave stone plate. What is more, there are nice holograms on the walls of the cylindric-shaped building from the inside, demonstrating yet another artistic solution of light and optical properties.
|Schematic drawing of a pin-hole type Camera Obscura |
"The principle of the camera obscura is as simple as it seems magical even today. The windowless box or chamber has a small hole in one site and a white side of wall opposite the side with the hole. Light entering the camera obscura through the hole projects onto the screen wall, and (following the laws of optics) produces and upside-down and reversed image. Most camera obscuras were fitted with a lens in the hole to focus the image. In portable form, the camera obscura became popular for recording landscape and city views. Using a system of lenses and mirrors that allowed the image to appear on a translucent screen, draftsmen could trace the views to produce early versions of tourist snapshots. The rooms-sized version of the camera obscura was useful to scientists interested in the behavior of light." 
If you are a really keen physics or optics enthusiastic who also loves to travel, there are many other Camera Obscura buildings around the world that’s worth visiting. Some of the examples are: Havana (Cuba), several in California, New York (USA), Mülheim (Germany), Edinburgh (Scotland), Bristol and Todmorden (England), and others.
|Postcards from Camera Obscura|
 Cliff House