10” Carl Zeiss Refractor Telescope Ultra Precision Custom Made 25mm


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10” Carl Zeiss Refractor Telescope Ultra Precision Custom Made 25mm

This is a research grade refracting
telescope of ultra-precision quality, both mechanically and optically. The
objective lens is a Carl Zeiss 25cm (10”) clear aperture with focal length if
411cm, approx. 162” or 135’ to focus. The optical correction of this instrument
if superb with minimum chromatic aberration for a 10” lens. However, the small
chromatic error (color) is removed by a custom 100mm fluorite zero power
element 90” up the beam, which was custom made by master optician, Mr Rolland
Christen, a renowned maker of triplet apochromat optics and refractors.

The Zeiss 10” is a one a kind large
refractor of this special color correction. It permits clean sharp studies of
such places as planetary surfaces markings, the sun’s surface details, the
moon, double stars; all at high power and highly precision level of
professionalism. The telescope has a large collection of the best accessories
ever made , such as Clave eyepieces, Brandon custom eyepieces, special devices
for looking directly at the sun’s surface details safely, a special filiar
“micrometer” for measuring distances between double stars, the height of lunar
mountains, etc… There is a Zeiss Bino viewer for using both eyes while viewing,
an optical collimator for aligning the main lens – squaring it to focus exactly
center. There are many more accessories exceeding $8000 in value.

The custom-made optical tube assemble
is a very precision device. The main optical lens and cell (Zeiss) is carri4ed
by a massive adjustable spring loaded cell which allows exact squaring of the
beam to the rear center of the tube within .0001”. The 3” f-10 finder telescope
has a custom Carl Zeiss type A semi-apochromat of optical correction. The tube
assembly for this finder was custom made and designed at great cost and is
precise. There are many precision devices clamped and adjustable round the
tube, which provide balance and other functions. They’re precisely machined and

The prime focus mechanism is a two
speed ultra-precision device with no backlash, no play. The fuill optical tube
weighs approximately 197 lbs. Besides the 10” Zeiss main lens there is also an 88”
lens and custom mounting hardware of equal quality. The two compound lenses in
the Zeiss 10” crown BK7-fint2  are spaced
.018” @ 120 degrees. The equatorial mount, which carries the scope is a massive
ultra-precision example. The 18” diametrical pitch 570 tooth worm wheel is
driven by a 2” 174PH SS worm of precision stability ground to a precision
performance of 2 arc seconds error. The North Polar bearings on this munt are
7”. The shaft is solid 5” O.D. with pre-load adjustment at the rear of the mount.
The declination axis has a massive tangent arm driven by a globe D.C. planetary
gear motor. The electronics that control his scope offer precision tracking of
solar, lunar, planetary, stellar and all are adjustable I n increments via a
precise micrometer read out pot mounted on a handle [paddle. The hand paddle
also provides slow tor fast movement in right ascension or declination with
instant stop. The entire 197lb scope can track like a watch, a planet or be
moed away to position it at the push of a button. The color correction
mentioned earlier rides in a complex adjustable carriage. When released,
3-split clamps allow sliding to and fro for proper distance up the beam for
best color correction, once set never has to be changed so this adjustable carriage
is over-kill but nice. There are just too many other things to mention
concerning the telescope tube accessories and their functions.

There are 11x 18lb counter weights
with nylatron acme threads, 8 per inch for smooth adjustment. The mount also
has a unique differential gear system behind a lit glass window, which allows
slow and fast corrections – without disturbing the clock tracking. The 7’
tapered pier the mount sits on is made on a Bridgeport Jig Mill from 2024 T6 ½”
aluminum sheet and assembled by drilling, countersinking, and tapping 1200
allen screws aporied and hidden  in the
semi-black cardinal polyurethane paint, which was professional sprayed. The
paint job alone was $3000.

The telescope is a rugged precision
professional instrument for studying planetary features, solar, etc. and is for
someone who wants a fine instrument and is interested in astronomy or if
scientifically curious. The telescope will last for an untold amount of years,
is highly color corrected and took over dozens of drawings, over 20 years and
$80,000 to build. The builder had planetary and lunar photos published.

The mount and electronics to control
it alone woud be over $50,000 to manufacture and assemble today. It’s extremely
difficult regardless of expenditure to acquire a 10” refractor of this optical

The owner has offered to help the
buyer set up and adjust it with up-keep tips. He’s done much successful work
with it and has made many scientific friends here and in the world by creating
this instrument. He is now ready to pass it over to a new home.

What it would cost to make this today
would be staggering, let alone being able to find this optical quality lens,
which only a few people in the world could make this well. Tolerance on this
type of optics are extremely difficult to make 1/1,000,000 of an inch final
correcting that can only done by hand of a master optician. Only a hand-full
were able to make really good ones, but they couldn’t mass produce them. Good
lenses, excellent lenses and superb lenses were a result of these talented
opticians and the difference can be seen.



The heart of the instrument is a
first class Carl Zeiss Type E objective lens with excellent color correction – considering
its aperture. The Rolland Christian 100mm zero corrector makes it a super
apochromat of large aperture and stable performance. The mount and pier are
painted with semi-gloss black polyurethane that cost $2600. The finder is a
custom Carl Zeiss Type A Semi-apochromat F-10 75mm 3” diameter objective,
handpicked and fitted into a highly custom finder brackets and 304 SS focus
knobs and internal stops. A Carl Zeiss 60mm Ortho with crosshair eyepiece is
included. The mount is massive with an ultra-precision 18” gear, 5722 diameter
pitch and a 2” precision ground worm of 17-4 PH SS. 5” diameter solid Polar
axis through the North bearing is a 5” precision differential gear system for
“flaso” correction in declination and RA without disturbing the tracking rate.
Declination is controlled by tangent arm of ultra-precision. The cradle holding
the tube assembly is machined and on precise hinges of 304 SS. An adjustable
rod for clamping declination is centerless ground 304 SS. There is also a
precision electronic drive clock and hand paddle with precision RA track
corrector in slow motion settings. Electronics custom munt on piier and weight
of munt is 305 lbs.

A 100mm zero color corrector over the
complete field yielding a stable image, a 25cm F-16 apochromat Carl Zeiss Jena refractor,
which provides sharp & clean images. The main lens cell fits in an
elaborate, self-adjusting push-pull cell for precision squaring. The corrector
rides in a precision adjustable assembly. There is also a beam splitter,
optical objective lens collimator with its power supply included. The main tube
is approximately 12’ long, has a 12” outer diameter and has a satin white epoxy
powder coating. The dew cap is 21” long and is 13.5” in diameter. The precision
machined tube has 6 stops, the tailpiece is segmented for access to different
focal points, a precision feather touch focuser with custom mounting assembly.
There are custom clamp brackets of 70-75 T-6 aluminum hold 304 SS, ¾” rods,
centerless ground and aluminum weights; which slide for balancing up and down
the tube. The pier is custom made of ½”, 20-24 T6 aluminum and has a massive
foot with a very stable outcome.

There is also a custom massive
adjustable latitude wedge for settings anywhere in the world. The mount is
currently set for 34 degrees latitude. The pier is bolted to a custom platform
with 8” casters and custom leveling screws of 304 stainless steel.








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