When taking wide angle photos underwater we observe a remarkable effect: if we look up in quiet water, it appears that we can look at the world above water through a circular window.
Circular window
The reason is found in Snell’s law, which states that light is refracted when going from one medium to another medium with different ‘refraction index’. In our case light goes from air to water. Light propagates not in a straigt line, but is refracted.
These articles I wrote for the scuba diving club:
Deel 2: Lens, brandpunt en belichting
Deel 5: Uitlichten: natuurlijk licht en menglicht
At some dark parts on this globe we have a beautiful view on the milky way. It shows as a lighted band on the nightly sky. It is possible to capture it on camera. The fun part is: The camera can see more than the naked eye.
It requires a SLR on tripod and a bit of technical knowledge. This shows how easy it is. Hardest part is probably to find dark night sky, real dark night sky.
More info on https://www.studioblueplanet.net.
ISO200, 12mm, F/5.0, this photo has an effective exposure time of 90 minutes
The trick is not to expose one image very long, but to combine multiple photos into one image. The image above consists of 9 photos that were exposed for 10 minutes each (1.5 hour total).