Zeiss
Telementor 63/840 Review
The Telementor was made by Zeiss in communist East Germany as
a response, so the story goes, to a government edict that all schools shall
have a telescope (and who said communism was all bad), hence the name!
Today the Telementor is much prized for its high optical and
mechanical quality, although unfortunately is has also been swept up in the
general collector’s mania for all things Zeiss, so prices from dealers can be
high and some are a bit jaded from a hard life at school (something any teacher
will relate to).
The original for this review was owned by a friend. Many
years later, I bought myself a Telementor OTA to re-visit it and expand this
review.
At
A Glance
|
Telescope |
Zeiss
Telementor |
|
Aperture |
63mm |
|
Focal
Length |
840mm |
|
Focal
Ratio |
13.3 |
|
Length |
81.5cm w/o
visual back |
|
Weight |
OTA – ~3.2Kg
w/o rings |
Data from Me/Zeiss.
What’s
in the Box?
The box for the original Telementor in this review came
wrapped in a big piece of heavy orange sailcloth or tarpaulin – all part of the
“they don’t make ‘em like this anymore’ Telementor
mystique. I can’t find the photos, unfortunately.
Design
and Build
The Telementor has a unique style and
build, partly because it was designed in East Germany, mostly because it was
designed for the gentle handling of generation after generation of school
children.
The Zeiss Telementor objective is a ‘C’
lens – no spacers.
Air-spaced Zeiss 50/540 ‘E’ lens. Note
the foil spacer.
Optics
The 63mm F13 (840mm F.L.) achromatic doublet is held behind a
lock-ring in a beautifully-made black metal cell (nothing like your typical
60mm achromat), but you never get to see it because it sits way down inside the
OTA. A torch reveals quality coatings, even if single.
These lenses have a very strong reputation for quality and
from what I’ve seen of bench tests that reputation is warranted. The same bench
tests indicate a level of chromatic aberration similar to a fast ED doublet semi-apochromat,
but the deep sky image below suggests it’s a bit worse than that, at least for violet
bloat.
The Telementor lens cell design is similar to later versions
of the Zeiss 50/540 Optiksatz lens. The Telementor
has a slightly slower focal ratio, but false colour is much more noticeable in
the Telementor: the 50/540 really is at fast apochromat levels, whilst just
10mm more aperture means the Telementor is a well-corrected small achromat,
albeit a fine one.
However, there is another small twist to the tale: the early Optiksatz ‘E’ lenses (like the one I reviewed) are
air-spaced doublets and perform slightly better than the later ones which are
cemented doublets (‘C’ lenses). The Telementor is a cemented doublet – a ‘C’
lens like the later Optiksatz lenses – no foil spacers.
It even says ‘C 63/840’ on the brochure (see below).
Tube
Just a 63mm scope it may be, but the Telementor is large and
unusual in design. It also weighs about as much as a truckload of Chinese 60mm
scopes on account of being built from spare battleship armour (well that’s how
it looks and feels). If you teach, or can still recall your own school days,
you’ll know why. Compared to a functionally-similar Takahashi FC-60 it’s huge.
If not actual armour plate, the tube really is very solid
metal for a telescope (steel, a good 1.5mm thick), which accounts for its 3.1Kg
basic weight (sans visual back and dovetail). Appropriately, the tube is coated
in a hard battleship-grey enamel.
The Telementor has no optical finder, just a pair of
gunsights at top and bottom of the tube: less for over-enthusiastic school
children to snap-off or for me to knock and mis-align.
That long, grey tube is a Telementor hallmark and the OTA
does have a certain charm: it looks a bit like a small howitzer. I imagine a
stern but handsome school-mistress brandishing it at a class perched on hard
chairs in front of small, ink-stained desks.
Internally, the OTA has three knife-edge baffles to kill
stray light and help contrast. These baffles are not fixed in the tube like
usual, but are part of the objective lens assembly that slides to focus.
Internal quality is very high, with careful blacking and micro-ridges like a
camera lens. The workers at Zeiss Jena evidently wanted their kids to get an
inspiring view!
You might expect the Telementor to be all odd proprietary
sizes, but in fact the tube is a very standard 80mm diameter and ends in an M44
thread. No daft pounds and inches for those coldly rational Commies.
Telementor
focuser assembly moves the objective inside the tube.
Older version of the Telementor with a helical focuser (image
credit Ed Harrison).
Focuser
The focuser is very unusual for a
refractor – much more like your typical SCT or Mak’.
The visual back stays put and focusing is achieved by moving the lens cell up
and down the tube via a single knob mounted about a quarter of the way up the
OTA. Of course, CZJ designed it that way to make the scope more rugged.
It sounds like a recipe for image shift
and horridness, but in fact it works well. The action is a bit stiff, but it’s
accurate and has loads of travel to accommodate different eyepieces or a camera
with no extension required. There is virtually no image shift.
Note that some older Telementors have
an external helical focuser (see above).
The Telementor’s supplied visual back is only set-up to use
0.965” EPs. This has the reputation of being hard to get around; it isn’t: you
just need to buy an M44-T2 adapter and a T2 eyepiece holder. I bought these
cheaply from Amazon and they arrived next day. Your camera T-mount will thread
straight on to the adapter too and no worries about whether the focuser will
take the weight.
Mounting
The Telementor’s mount is a simple, robust, non-driven (in
most cases) German equatorial, finished in the same grey as the tube. The mount
has precise setting circles and nice chunky slow motion controls which are brightly
colour-coded to indicate which ones you should twiddle in the dark and which
not (maybe I’m an idiot, but how many times have I reached for the wrong
identical knob on my Takahashi P2Z, TG-SP or Vixen SX2?)
The mount is supported by a lovely beech-wood tripod with
sculpted and curved wooden legs and blue metal parts. The tripod reminds me of 1960’s
Ercol, of school desks and chairs; if only Tele Vue
tripods (or even Berlebach) were built this way.
The
Telementor attaches to its mount via a dovetail. The dovetail is slim and
shallow, but the chamfer is the same angle as a Vixen/CG5 dovetail and all you
need is a longer clamp screw to fix it to most Vixen and Skywatcher
mounts. Alternatively, undo the three screws holding the dovetail on and mount
the Telementor in any pair of 80mm (a very common size) tube rings or
clamshell.
Some
Telementor mounts had a drive motor under a strange-looking curved metal shield
(thanks to those kids again).
Catalogue
image shows the Telementor on its original mount.
Accessories
Zeiss
produced a range of distinctively-styled 0.965” eyepieces for their scopes –
mainly orthoscopic and Huygens types - and the orthos
particularly command quite high prices today (if not in the Abbe Ortho’
league). My experience writing this review is that they are indeed of high
quality, even the Huygens.
The original
visual back doesn’t work for ‘normal’ eyepieces, so the main accessories you
will likely need are that M44-T2 adapter and T2 eyepiece holder discussed
above.
Then the OTA
is usefully a standard 80mm O.D., so rings or a clamshell are easy to source. I
used a Takahashi FS-60 clam initially and later a pair of Borg
hinge-less 80mm rings (I had to remove one of the gunsights to slide them on).
The Telementor
was supplied with several quality 0.965” Carl Zeiss Jena eyepieces, including
this Huygens 25mm and Orthoscopic 16mm.
Converting the Telementor to use 1.25” accessories just needs
an M44-T2 adapter and a T2 eyepiece holder.
In
Use – Daytime
At 56x with a 15mm Tele Vue Panoptic,
the view is very sharp, but with some minor false colour.
My usual test, branches in silhouette
at ~100x, gives a sharp view; but there is some purple and green when focusing
through or around any parts of the view not perfectly in focus. The level of
false colour here is a bit worse than a 60mm F6 doublet apochromat like
Takahashi’s FS-60, or the Zeiss 50/540 ‘E’ lens.
You can see this false colour in the
snap taken through an eyepiece at 93x below.
However, lower contrast views during
the day are good at moderate powers, although the single lens coatings mean the
Telementor is noticeably dimmer than a modern 60mm for a given power.
Eyepiece view at 93x.
Prime focus – sharp but with
significant false colour.
In
Use – Astrophotography
I often talk about modern refractors
‘tuned for imaging’, i.e. to control the blue-violet end of the spectrum to
avoid bloating on O-A stars. Well, the Telementor is evidence of the exact
opposite. For visual use at night, chromatic aberration is always well
controlled. But images through the Telementor show a lot of blue bloating, even
with short exposures: worse than a Tele Vue Genesis, another well corrected
achromat, for example.
The example below is just 30s, a short
exposure at F13, but still shows a lot of violet bloat.
That violet bloating of stars doesn’t
spoil things for the Moon and the Telementor produces good lunar images.
APS-C sub of Pleiades: 30s at ISO 3200.
In
Use – The Night Sky
General
Observing Notes
The field is
very well corrected, even in a 32mm Plössl, with just minor
elongation of stars towards field edge. Zeiss Jena knew a thing or two.
The Zeiss
H-25 and O-16 eyepieces (Huygens and Orthoscopic) are a good match, as are
Takahashi’s MC orthos. Perhaps it’s my imagination,
but orthoscopics seem to work a little better than Plössls in the Telementor, with a slightly easier,
sharper view.
That focusing
mechanism is odd, but it certainly protects the lens and it works well enough –
with plenty of travel. This one is a bit too stiff in places, though.
Cool
Down
Despite its weight, the Telementor
cools fast like any small refractor and still offers decent views whilst doing
it.
Star
Test
The star test
is basically perfect, identical either side of focus, as you’d expect with
well-figured spherical surfaces. A bright white star like Rigel does give some
purple in the star test.
The
Moon
One cold
morning in late November, I woke to a slightly hazy sky but stable seeing. A 23-day
waning crescent Moon was high in the sky on the Meridian. Meanwhile, darkness
was falling on Craters Plato, Tycho and Eratosthenes.
A
magnification of 93x with a 9mm Nagler easily embraced the whole Moon and gave
a fantastic view – hard and full of contrast in shadowy crater and brilliant
highlands, from limb to limb. At that magnification there was almost no false
colour except a thin rim of purple between bright rim and black space.
Upping the
power to 119x, the Telementor stayed just as sharp and the whole Moon still just
fitted into the field of a 7mm Nagler. This turned out to be the Telementor’s
favourite power for the Moon. A 5mm giving 166x was still sharp, but revealed a
bit more false colour on the limb and no extra detail.
I followed
the terminator from north to south. Plato’s rim was spreading long peaky
shadows past the middle of its darkening floor whilst Eratosthenes’ floor was
already in black night-time. East of the Terminator, Copernicus showed its twin
central peaks and terraced walls. Further south in the shadows of evening was Pitatus and beyond it Tycho, now a bottomless black hole
with just the western rim dazzlingly lit.
Right in the
far south was Clavius, its arc of craters throwing long shadows. Beyond, on the
very horn of the crescent, a single peak stood out surrounded by blackness.
Nearby, rounded mountains rose from the very edge, the bright limb abutting
black space, revealing the true shape of lunar mountains – something you only
see with a quality optic.
All with a
60mm achromat! The
Telementor, true to lore, makes a super Lunar scope.
Planets
Some brief views of the planets – Saturn, Mars and Jupiter - in
unfavourable (i.e. at altitudes of 15° or less) circumstances
suggested the Telementor performs well. When the planets return to higher
altitudes in 2020, I will (the Fates willing, of course) update this review
with more planetary observations.
Deep
Sky
The Great
Orion Nebula, M42, looks quite bright and with some nebular detail, a view typical
of a good 60mm and not very different from my Takahashi FOA-60. I particularly
liked the view with the originally supplied Zeiss H-25 at 24x: yes, it
distorted the sword stars off axis the way a modern EP would not, but the
nebulosity seemed a touch brighter and more structured. The O-16 at 53x acquitted
itself well too – sharp and bright.
All seven
sisters fit nicely in a 32mm Plossl or 40mm Tak’ MC
ortho and the good optical figure means pin-point stars. But I thought they
were a little less sparkly, the nebulosity less misty and obvious, than through
the next door Tak’ 60mm with multi-coatings. For such
an extended object, the H-25 distorted the outer stars and the shape of the
cluster too much for a really good view.
The
Telementor has a reputation for double stars and deservedly. The Double Double was a very easy split at 120x in decent seeing. I
struggled with Rigel in poor seeing, but the faint companion did pop out
briefly a few times, only to disappear back into Rigel’s boiling diffraction
rings.
The Starfish
open cluster in Auriga (M38) looked an attractive dusting of stars with
radiating arms, perhaps just a bit fainter and more needing of averted vision
than through the modern 60mm next door.
With a small
aperture and long focal length, the Telementor isn’t an ideal deep sky tool,
but it gives great images nonetheless; as it must have done to a generation of
school kids in East Germany.
Summary
The Telementor, whether as an OTA or a complete setup, is a wonderful
classic scope that’s frankly way more usable than most small Tascos and even Unitrons on the opposing team during the Space Race era. It
works well on most things, but is truly excellent for the Moon and doubles,
just as legend has it.
Overall, the Telementor has a rugged, serious, dare I say
scholarly charm that is hard to explain. It all has a no-nonsense Eastern Block
practicality and solidity I really like.
Optical and mechanical quality are ridiculously high for its
intended purpose, close to military equipment standards, in keeping with its
looks. Something similar would likely be very expensive to produce today.
It is a great optic, but don’t believe stories about this being the
same as a 60mm apochromat with modern coatings – it really isn’t. Also, try not
to pay collectors’ prices. These shouldn’t be priced like an APQ.
The Telementor is one of the most usable and useful classics,
especially if you like the Moon and double stars. It is very highly
recommended, but not at Zeiss collectors’ prices.