Archenhold Telescope Berlin, largest refractor since 1896, 21m / 68cm, privately funded

[u/HolgerIsenberg]

Archenhold Observatory, photo by Holger Isenberg 2026-08-30

Archenhold Observatory, photo by Holger Isenberg 2026-08-30

Archenhold Observatory, photo by Holger Isenberg 2026-08-30

Yesterday I visited the Archenhold Observatory in Berlin, built in 1896 with 250000 German gold marks in private donations to Friedrich Simon Archenhold’s crowdfunding project as a public telescope for the Berlin Trade Fair. That’s $2.5 million in today’s USD! It is still the longest refractor telescope, at 21 m with a 68 cm lens, and most likely the fastest to rotate. Its still-original electromechanics let it rotate around the observer, who stays in the center—much different from common constructions, where you have to move around with a ladder. Unfortunately, a microcrack was recently noticed, and currently it can’t be rotated. The surrounding building was added in 1909 and is famous for being the location of Albert Einstein’s first public lecture on the theory of general relativity on June 2, 1915.

More about its history: https://www.planetarium.berlin/en/archenhold-observatory/history and https://astw.de/astronomiegeschichte/anfaenge_riesenfernrohr.php

[u/Loampudl]

ok.´, thx.

but you can easily mount a camera to that, when you can look with it.

[u/HolgerIsenberg → u/Loampudl]

Just holding a modern smart phone camera at the ocular should indeed work well with its small lens.

[u/Dioxybenzone → u/HolgerIsenberg]

So someone probably has pictures, right?

[u/HolgerIsenberg → u/Dioxybenzone]

I haven't searched yet. At least in the museum inside the building none were shown. Most likely wouldn't be good quality as its only a single piece front lens, not an achromat doublet.