A 1960s ZEISS AS-100/1000

The Story of a Terrace


This is the story of a terrace.

A small terrace in a countryside house nearby an observatory. A terrace exposed South-South/East that has been screaming for a long time to host an instrument -- a nice refractor (...we are in Refractorland, after all...;-)

A nice refractor for a quick glimpse with dear friends early in the evening (just before dinner) or late at night (just in between two pieces of wood in the fireplace...), when everything around is silence and one can smell nightly nature and listen to crickets and owls; when dragonflies start floating around...

You know, not necessarily an instrument for hard science; just a beautiful classic instrument: one of those "time machines" able to turn Astronomy into a global experience, involving nature, science, memories, history...

The only problem is... this old terrace is really small... a bit more than two square meters... open on two sides, while the two others are old stones...

For a while I gave it a try with a Cde-corrected SYW 108/1600 refractor.

Nice, truly nice. But a bit longish for the space. OK, let's say cumbersome...;-) In short, managing the long OTA spanning over the small terrace was somehow spoiling all the magic of the experience.

Therefore I decided to downsize the scope. The SYW 108/1600 moved out, and a Zeiss AS-80/1200 moved in. That was a more appropriate OTA for the space. Missed a bit the light throughput of the 4", but the Zeiss did deliver resolution up to the previous instrument.

Then at certain point, for life reasons, the AS-80/1200 found a new *happy* owner.


---- Addendum ----

Actually lately another AS-80/1200 moved in...! The one that you may find here. Only, I did not feel that such an old telescope could be kept there for evening enjoyment. I don't know, maybe I have a mistaken feeling. But the previous AS-80 was a "new" OTA, custom-made around a lens. While this other AS-80 is not just "old", rather "historical". It belonged to a renown post WW-II scientist... So I felt, and still feel, this is more something that you look after and you transmit, than something that you use while holding a glass of wine in your hand... anyway...

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In the meantime I had given it a try with a *very nice* Royal-Astro Cde-corrected 76/1200. But no, that was not the way. Although it gave better views than my Unitron 142 (...tried them side by side a number of times: 142 is *really* nice, but the R/A is better when pushing high powers), it was honestly no match for the Zeiss. And I was still missing the light throughput of the SYW-108.

What to do then...?!

The solution seemed to be an instrument that was, at once, a "classic', with the light throughput of the SYW, the contrast+sharpness+resolution of the AS-80/1200, and possibly even less cumbersome. And a refractor, of course..;-) If nothing else, for the no-issue design and for the "quality" of the images.

Thinking it over and over, I always found myself back to the AS series... But the good, old, trusty AS-110/1650 was out of the question for its size, bigger than the SYW... Well, that's my problem: I like long-focus...;-)

But, then, what about a short-one...?! In the end, I thought, a Zeiss AS, in Steinheil KzFN2/BK7 configuration has a secondary spectrum of about 1/2400 vs 1/1850 of a standard Fraunhofer BK7/F2 achro. And, on top of that, has the exquisite Zeiss figure.

I remembered my various tests with two AS-63/840 against two Royal-Astro 60/1200... the R/As were really *white* on everything including Sirius, but, beyond 200x, the AS-63 gave no mercy.

So, what I was looking for, in the end, was a 4" refractor that would have similar chromatic correction of the SYW, with the figure, contrast and construction of a Zeiss... in a smaller package...! Well, in the end the answer for the small terrace was just before my eyes: an old -- but not too old ! -- AS-100/1000. Something in between the AS-80/1200 of the 1950s and all the other instruments that are of 1970-1980 vintage. A cousin of my AS-110/1650. Just shorter.

Well, this is easy to say and to write it down. But to find a 1960s OTA, born behind the Iron Curtain, in full working conditions, together with its mount and accessories... this is not something you get at the shop next door...

So this project started in the silence, and little by little, for some 12 months or more, I went on picking bits and pieces here and there, having the final instrument in mind. An instrument that, in the shadow, took shape. From the single Huyghens eyepiece for Solar projection to a double Huyghens-Ortho series that would cover both Solar and Lunar/Planetary observation (not to mention a bit of deep-sky), to the different Moon filters, to the Sun, and the Mars one, to the filter revolvers, to the big prism diagonal, the huge Porro prism for terrestrial use, the multiple turret, the solar projection screen, the focuser, the OTA, the finder, the case, and then the pier, the mount (a I-b), a working engine and, in the end, the lens. A perfect AS-100/1000 lens.

And then, of course, carefully cleaning and restoring every single piece when it was (and, boy, it was...!) the case, always keeping in mind that small terrace and the blue sky of the early evening, when you await with friends that the meal gets cooked on the fire, having a glimpse of the Moon, or Venus, Jupiter, Saturn, Mars, or M42, M45... just anything that could make one fly high.

And now, after more than one year, it's done. Finished -- if the restoration of a classic is ever finished -- just last weekend.

Here are the first pix: a full Zeiss AS-100/1000 of the 1960s, which more than one year ago did not exist -- although the different components did, dispersed in different parts of the world. It's here: one can see that the whole is indeed *more* than just that sum of its different components.

For your eyes, distant CN friends, and for the dear friends who'll get to use it in Refractorland.



The Zeiss AS-100/1000 in its original case with some of its accessories.
From the left: Porro prism, 90 deg. M44 prism diagonal, the lens in its box, the 4-eyepieces turret in its box.
Solar projection screen. 4 (four!) filter eyepiece revolvers. In the case, just few of the eyepieces.
Among them an Ortho-40 and a Huygens-40 mm.



The Zeiss AS-100/1000 on the I-b mount, on top of its 120 kg solid cast iron pier...!



Idem. Just a closer look. Beautiful.



Getting closer to the "controls".
Note that the counterweights bar end with a dovetail clamp for the 9x12 cm Astro-Kamera (not shown).
Found that one as well...;-)



A better view of the Turret with one of the filter revolvers.
The Ortho-40 does not accept filters. The fourth revolver belongs to the Huygens-40 (not shown)



Reverse view of the whole setup.
Yes, we are on top of a hill.


Now, the main problem is that, unfortunately, the recent earthquake of April 6, slightly damaged that small terrace (and other parts of the house). Nothing very serious in comparison to the dreadful damages occurred only 60 miles nearby. In any event, now the terrace has to be revamped as by no means could safely handle the 150 kgs of the full Zeiss setup concentrated in 60 cm plus people around... Well, now situation seems reversed... got an instrument which is seeking for a terrace...;-)


That's all for now. More pics and report coming soon.
Hope you liked it. Thanks for reading.


-- Max


PS/ If anyone has the lens of an APQ-100/1000 of that era, I could be interested -- in the original Zeiss design one could just unscrew the lenses on this OTA and "upgrade" from AS to APQ. Or, rather, use one for solar work and the other during the night... Good old times...;-)