50cm Newtonian

50cm Newtonian on very heavy mount

Update 2022-05-14:

Today, we unmounted the big telescope: first the primary mirror, then the secondary and finally we took the “skeleton” (the truss-tube) of the mount.

And we were in for a big surprise: once we cleaned bit mirrors (very very delicately, first removing all the dust under running water – and then cleaning it with an oh-so-soft soapy water) both looked almost perfectly! No oxidation, nor any other deterioration. They are almost as good as new!

After cleaning! Not the slightest trace of oxidation…
Before the cleaning: even in a closed telescope tube one still gets a lot of dust…
After the cleaning…
The truss-tube system (+ the light-weight tube to block stray light) probably weights around 50 kg (not easy to weight such a structure).
The mirror itself weights almost 27 kg. To that, one should add the mirror cell – the secondary mirror and its spider, and of course the focuser. So all in all, this telescope comes close to 90kg…
The primary mirror cell, with three ventilators attached to the bars of the “whiffle tree” system. Notice the black triangle – the other 5 are still glued to the underside of the mirror – together with those 3 bars they make up the “whiffle tree”
One of the 3 bars of the “whiffle tree”.
The gigantic secondary mirror, with one of the 4 vanes making up the spider.
Only the tiniest hint of oxidation right at the lower border (on top on this image)
Underneath the primary mirror: sensors controlling the 3 fans…
Declination motor block: belt-transmission
The sheer size of this mount (Knopf MK100S)! The counterweight bar has a diameter of 50mm, and according to the manufacturer it can carry 150 kg of photographic gear).
Heidenhahn encoders!

The corrector (Philipp Keller, ASA) reducing the focal ratio to f/3.3
The Keller-corrector, here seen next to the huge Apogee-camera for size-comparison.

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