The original appeared on https://xkcd.com/1855/ (a web site perfectly suited to geeks, photographers or not).

photo credit: anthonycmaki

Sometimes, during Summer time, it’s fine to switch to low gear and to wander far from the normal path of things.

So, if you like lenses (specially long focal length primes), you may be interested in looking at the dinosaur age of tele-lenses: The Telescope era, which started in 1611 (nearly 400 years ago) when the Greek mathematician Giovanni Demisiani coined the word from the Greek τῆλε, tele “far” and σκοπεῖν, skopein “to look or see”; Thus, τηλεσκόπος, teleskopos “far-seeing”).

ArsTechnica has a fine 3-page feature article drawing a history of the telescope, showing how it evolved from the original 2-lens design of Galileo telescope to more modern mirror-based ones. In between the tele-lens derived from that, but it’s another story.

Fun reading. Good lesson ni optics.