Black Enamel Microscope.
Ian Walker. U.K.
There has been much written over the
years about this microscope
and in this article I will try to avoid too much duplication of the
already thorough articles written in Micscape by Paul
James on the Heine condenser
, Gregor & Normand Overney's article on
Leitz Stands in Black Enamel
and the resources supplied
by Gordon Couger on his science-info
website to name but a few. It is
quite possible to assemble substantial documentation on manuals,
accessories, optics etc giving the user detailed knowledge on the
microscope. Here I give a tour and some
hands on thoughts on using the scope perhaps with the aim in mind of
giving details that may be of useful to microscopists considering it as
their next purchase.
At first glance seen in pictures on the web, brochures or books, the
would be purchaser may consider it of large and heavy build, although
substantial using a light alloy casting, it is perhaps smaller than
one would think measuring 32.5cm (12 3/4") to limb top
and 37.5cm (14 3/4") to the centre of the eyepieces on the trinocular
head fitted to this stand. Side by side a Zeiss Photomicroscope seems
noticeably larger, in fact on some desks or work tops it may need a
plinth beneath the base to raise to sufficient height for comfortable
It also has a relatively small footprint due to its 'T'
allowing low slung controls, although it is quite deep due to the
protruding lamp housing at the rear. Provided you are not moving it
about many times it can transported short distances
comfortable grip around the upper limb and support beneath, preferably
with the lamp assembly removed.
Schematic of earlier Ortholux with single lamp. Ernst Leitz
Note the lack of field iris, swing-in auxiliary lens and
diverter mirror for epi-illumination. The lens after the lamp
filament is frosted.
Three variants of the Ortholux black
enamel stand are to be found,
the older one dating back to the late 1930's when the Ortholux was
introduced, this has a single external lamp house attached to the
the light of which can be directable by lever allowing
epi-illumination. With no field diaphragm this is ideally suited to the
condenser for routine work.
Later, two ports are situated on the rear of the limb
allowing mixed lighting of epi-illumination and transmitted. This can
be used as a
rough guide to the date of the stand if you have seen one and don't
know the serial number. In Gregor & Normand Overney's article on
Leitz microscopes of the period they show a version
fitted with dual light source in 1960 and later still,
dual light source and field diaphragm 1966.
In the 1970's the Ortholux
II stand was introduced similar in appearance to the Orthoplan with its
squarer modern lines.
Less detailed schematic from Leitz showing a later Ortholux.
Ernst Leitz Wetzlar documentation.
Using a 1956
Leitz Ortholux fine
engineering can be seen throughout with excellent tolerances on moving
parts whilst fit and finish put to shame many a stand of today. Relying
on decades of experience prior to the Ortholux, Leitz produced a stand
where the quality of all parts speak for themselves, to make a
the same standard today would be costly indeed!
Fine engineering on the Ortholux.
The Ortholux was the earliest microscope to use a totally
approach in the way numerous accessories could be added to the basic
fluorescence, polar, phase, epi-illumination etc. Before this
would sell the microscope for a narrow spectrum of use
limiting its versatility. As
we know, all have followed this route and stands of today of
research grade are built to take many accessories allowing the end user
to build up his or her specific requirements.
Clean uncluttered stage, fitted below is the centrable Berek
In the above picture it can be seen
the attention to detail to
all parts of the scope like verniers, slide carrier and finish on the
objectives, no cheap punched out or painted on parts of today but
engineered machining and all screwed together with impeccably finished
screws. The counterbalanced fine focus which acts on sliding ball races
is noteworthy, it has a lightly weighted action with great
precision at all magnifications (1 division = 0.001mm travel).
the coarse focus controls are relatively small and thin compared to say
Zeiss Photomicroscope they work well and have the right
gearing for precise control at high magnifications. The fine
has limited travel indicated by the white lines etched on the body just
above the left coarse focus control.
Schematic of coarse and fine focus.
Ernst Leitz Wetzlar documentation.
The stage can be
lifted and re-locked on its dovetail mount allowing objectives
with short barrels to
be used like the Lomo range which is useful on occasion, on many
this is not possible. You do have to get used to separate fine and
coarse focus again after using coaxial controls fitted to modern stands
it is cramped around the coarse and fine controls with the
focus lock lever adjacent to the coarse focus.
The nominal tube length
is 170mm but unless high NA dry objectives from 160mm stands are used,
interchangeability of objectives from other manufacturers is feasible
taking into account none
parfocality if mixed with the Leitz range.
Leitz DIN objectives with longer 45mm working were introduced later
suiting the phase condenser after Zernike, this earlier stand is fitted
Pv phase objectives suited to the Heine condenser and cannot be
used in phase with the turret condenser as the phase rings are
mis-matched although the bright field position is fine.
The thick black enamel still has a
lustre after 54 years, the focus lock lever can be seen in front of the
left coarse focus control. The lever on the left near the base front
swings in an auxiliary lens for the illumination, this is normally
left in the light path. The style of this lever changed on the later
Ortholux becoming a thin wedge.
Typical standard equipment from looking at the price listings of the
time for my Ortholux were a square stage with drop down X Y controls,
four turret nose piece (brochures also show a five as an option) which
works well with a positive click for
positions and numbering for objectives, at least on the four turret
fitted here. It works on the old
technique rather than a ring of many small ball bearings in the
turret perimeter often found in todays higher priced stands but
works with smooth, precise action and to complete the
up, a centrable Berek condenser seen fitted above.
The Berek condenser is a two diaphragm design the lower ring taking
over the role of the field diaphragm situated on the base of
most microscopes, the earlier Ortholux did not have a
field diaphragm in the base but later ones did
allowing use of the more modern Leitz turret phase
condenser. The long arm above the ring sets condenser aperture.
The condenser is of excellent optical and mechanical design being well
corrected and with the standard screw-in top allows maximum aperture
dry 0.95 but with the oil top (often missing today in sales) NA 1.4. If
you own the Heine condenser you can use the push on spring
filter clip that comes with the Heine allowing a small green or blue
filter specially shaped to
fit as this is inter changeable with the Heine condenser as they both
the same diameter tube at the bottom. The Berek top element may be
swung out of the optical path by a substantial knurled aluminium
control for low
power objectives increasing its versatility with minimum fuss.
Dry and oil top for the Leitz Berek condenser.
Detail of trinocular head fittings.
pictures below shows the
sprung release leaver for the viewing head, the latter being removed by
pulling up on the dovetail slider seen on the right picture. Also seen
on the left picture is the slider which permits 100% of the light to be
either directed towards the photo tube or the viewing head (this later
changed to 80:20% photo/viewing or 100%viewing) this became a push-pull
knob situated at the front
of the trinocular body. Other viewing heads were the standard binocular
head and a monocular with upright camera attachment. Various camera
options were available at the time including large format film and a
smaller adapter with built in shutter for Leica cameras shown later in
Modern digital SLR bodies can be fitted to the trinocular port as a
standard 23mm tube is used and adapters are available today to convert
this to T2 mount or with further adapter rings to Canon, Nikon etc
suitable eyepiece will have to be selected, I believe there were
dedicated photo eyepieces but I would think a Periplan would suffice
purposes but this has not been tested up to writing this article.
It is surprising I think that
being of research grade the stand did not
have a dedicated slot for an analyzer or filter on the older Ortholux,
later ones did, seen as part of the nosepiece, the picture on the
shows a position recommended in the manual to place an analyzer which
was available as a Leitz polar accessory, here fitted with a home
made analyzer adapted for the purpose snugly sitting on top of the
protruding nose piece optic.
Details of trinocular mount, the right picture with home made
The large knurled control shown in
the above picture on the right is the release control for the
nose piece, care must be taken with this that it is sufficiently tight
not to let a fully populated nose piece and objectives slip and strike
the stage. This also fits on the lower part of the same dovetail and
the nose piece offered up
from below until it hits the stop provided with the stage dropped to a
low point and condenser removed, this action normally done at the first
assembly stage of the stand.
Illumination is in two parts, the
housing finished in black 'crinkle' paint is pushed home and clamped
into the optics enclosure. Three insulators isolate the heat from the
the main body of the microscope whilst some heat is allowed to exit
from the top of the ducted black metal enclosure, the optics enclosure
tight push fit
into the rear of the scope with no clamping whilst a filter slot next
to the port
can accept large glass filters specially made for the purpose. With the
filter fitted and 4 amps selected on the power supply bright, even
with good white balance can be obtained after adjustments, at the
maximum bulb rating no filter should be required for camera attachments.
Glass filters, left for Heine or Berek & right,
A 30 watt low voltage filament bulb
driven by an external AC power supply is normally used with the
Ortholux with the possibility of adding higher wattage specialist bulbs
and supplies for more demanding techniques with additional fitments to
stand. Directly after the bulb there is a fixed frosted glass lens
this prevents true Kohler illumination but is typical of many stands
and has become the norm of today. I would have preferred a swing out
frosted glass as this is inefficient and reduces light output when you
most need it at the limits of highest
magnifications and oblique illumination.
A variable collector lens in the lamp enclosure actuated by a long arm
adjusted to provide an even field which can be adjusted while viewing
with a 3.5x objective and wide field eyepieces or putting a
frosted glass on the base of the scope and viewing the effect of
adjustments. The substantial
alloy screw clamp holds the bulb housing in position also allowing some
further adjustment by loosening and pulling out the lamp slightly for
illumination whilst concentric
controls adjust the centering of the filament.
220V/120V ac mains power unit.
Measuring 19 x 12 cm (h w) this unit
provides low voltage ac power to the Ortholux, due to
the nominal 220V working for Europe, the 240V of British supplies
increases the amount of hum from the
transformer laminations although the Leitz documentation says it can be
used for 220-240v ac. The hum will vary from one sample to
the next and is made worse by the metal enclosure but was noisy on
this unit. Unlike Wild power supplies
with similar construction I have seen which have a dedicated
transformer primary tap for 240V
as well as 220V this does not.
There is no voltage indication only
current, a red line indicates the maximum recommended 6 amps for the
lamp whilst a large plug with its own on/off
switch brings the mains supply in together with on/off and variable
current supplied by the rheostat on the front actuating a sprung metal
with carbon roller which rotates up and down on the specially cut
of the transformer, crude but effective if contact surfaces are clean,
had no problems with flicker and output is steady.
A large range of objectives are
available for the stand too long to list here from high numerical
aperture apochromatics to long working distance and
epi-illumination in sophisticated single mirror mounts, both the
earlier 37mm and later DIN 45mm working objectives can be accommodated
as mentioned, the latter may be a safer bet as less likely to be
suffering the delamination problems which also cause grief
amongst buyers of Zeiss objectives of the period.
The Leitz pre DIN objectives mentioned in this paragraph worked
competently. Fitted to this stand were the 3.5x 0.1
achromat and three
Pv phase objectives: 10x 0.25 & 20x 0.45 achromats & 90x
1.15 oil immersion apochromat. Missing was any 40x objective. Although
not marked as such the 3.5x and 10x achieve good plan characteristics
for their age and give a fair account of themselves on many subjects
including larger preparations like plant sections or insect mounts, the
20x I think is rather under
whelming both in and out of phase use as the numerical aperture is
limited. The 90x apo performs OK within the limitations of its NA and
is suitable for dark field with the Heine (with oil top) or the
dedicated dark field condenser.
Out of a rather large but odd
optics and accessories supplied with the scope an
older style Periplan eyepiece and a 100x objective with iris were
suffering from severe delamination together possibly with the latter of
oil contamination behind the front element.. the objective was useless,
the former passable at best.
Worse was the
trinocular head forming a substantial part of the
stand. The scope was bought from a European dealer supplying optics on
eBay and was sold as optically and mechanically tested. Seen down the
left hand eyepiece tube was a 'near square' this required no testing
looking down the tube with the naked eye, so much for testing, it
doesn't even require the scope to be switched on! Delamination of the
splitter prism had caused a progressive shadowing of the field of view
worsening at the outer edges, the right tube seemed mostly unaffected.
An ultimatum was passed to the seller, either the lot goes back or a
substantial amount should be refunded and this was agreed.
paragraphs are for background reading, you can
skip to the condensers section later if you wish.
Hopefully the next few lines should form no part of a successful
purchase but included for completeness. All too
frequently things don't go to plan buying at a distance, especially
microscopes, objectives or accessories! We have all
probably had our fair share of supposedly tested items both on eBay or
from dealers only to find otherwise...
View down left eyepiece tube.
Do not try this at home!
into detail the defective splitter prism was separated into its two
component parts, the prism splits the
light path to the left and right hand tube prisms and consists of two
prisms the contact surface being
a 50% deposit (or thereabouts) mirror
allowing light to pass direct
to the left tube prism whilst at the same time reflecting light
right hand tube and is extremely
delicate. After cleaning where some dryback of the cement had caused damage to the surface, the
two prisms were offered back together with a very thin
layer of immersion oil, the two prisms 'locked' together by tape via
the none optical surfaces and offered
back to the mount, the latter is a simple copper or similar metal bar
with two screws
(see picture below).
Balsam was considered for the contact surface but considered a one off
process and if something went wrong in the alignment of the two prisms
the whole tube could be rendered useless so immersion oil was
considered the better option although medium term 'dry back' is likely
Alignment of the combination splitter
not to be taken lightly as it is a 3
dimensional puzzle, pressure from the two mounting screws together
with the prism slew in the mount in minute amounts affects alignment,
we are talking fractions of a mm here. Using a graticule
eyepiece and a finely divided micrometer slide alignment was achieved
with 1 division lateral error and zero vertically between the two
Small amounts of error between left and right tubes can
cause eye fatigue but I am happy to say I have had no problems.
I now see two round evenly illuminated discs with eyepieces
removed, the mirror damage is not visible whilst viewing but
can be seen looking down the eyepiece tubes with eyepieces removed. The
alignment itself is slow as an adjustment is made and the viewing tube
offered up accurately to the trinocular port, measurements made and
the process continued. A long term project is to seek a UK company that can resilver the prism face with a 50% mirror for a proper repair.
Viewing tube removed from trinocular port. note schematic
'flipped' 180 degrees.
Right image from Ernst Leitz Wetzlar documentation.
didn't get much better purchasing a Leitz 40x 0.95 apo objective
with correction collar later bought from a well
known European dealer to complete the turret as I have no Leitz 40x
objective, initial findings suggested it was defective
as the correction collar was always right at one end independent of the
range of modern and older slides tested and images were ill defined and
lack the 'pop' from a good apo. It turns out it had multiple
problems within the elements easily seen with a phase telescope and
indeed partially by a simple 5x lens with objective held up to a
More time wasted chasing refunds and yet another trip to the
office, they know me well down there! The response from the dealer
after time wasted checking, packing, paperwork, emails and sending it
back was 'better luck next time' ... there will be no next time! This
is by no means an isolated occurrence with eBay sellers and dealers
across the board over the years.
[Editor's note: Unfortunately Ian Walker's reported poor experiences with some mainland Europe microscope dealers also mirror mine, both buying and building up a Zeiss Photomicroscope III and major unnoticed faults of a Leitz Diaplan purchased.]
Is this the picture of a new planet, no it's one
plane of delamination on the defective 40x 0.95 objective pictured
using the Betrand lens of a Zeiss Photomicroscope!
A quote from an American
dealer left both me and my brother speechless, asking for a price by
email on their advertised Leitz 40x 0.7 Pv phase objective as no prices
were given on any items listed, the response was $700 and a further maybe
'up to $100' for shipping! It was obvious they had no interest in international
All the condensers on the Ortholux
use (approx) a 46mm sliding mount allowing quick placement, no
locking screw is provided you just push home the condenser to its limit
in its mount. All are solid and well finished and provided grease
hasn't hardened which is possible in the centering mounts and moving
parts which may need attention, are a pleasure to use mechanically.
Heine condenser with oil top removed, spring filter clip
and blue filter.
The above picture shows the Heine
condenser together with oil top removed and spring clip which can be
fitted to the bottom to allow the purpose made small blue or green
filters to be inserted safely. Some sales on eBay that I have seen, the
oil top and filters were not sold with the basic unit, I guess many
have been separated over the years from the condenser and get lost
which is a shame as it increases the versatility of the unit.
Unlike the Berek which I like for general use, so far I have not had
success with this condenser, yes it is
versatile allowing circular oblique illumination (COL), variable phase
and dark field to be achieved by the rotation of a single control for
different objectives but the ring of light I think is too thin no
matter the aperture
set creating what appears to be diffraction artifacts using COL, a
study of the optics I can find
no obvious problem but due to this phenomena phase is inefficient due
narrowness of the illumination ring and COL has gone past what I think
is its optimum
I do not agree with Leitz in their
documentation that the condenser operates smoothly at all settings
between bright field and dark field as the illumination always remains
one of circular oblique whether of larger (filling the back focal plane
of the objective) or smaller diameter (say within the phase ring of a
Pv objective). Yes, there is a bright field 'effect' but not the same
as say a standard brightfield condenser like the Berek and again the
image to me looks one of a condenser too stopped down at the majority
Heine condenser illuminating ring 20x Pv phase objective in use,
due to camera flare this is in reality a little narrower than shown
The illuminating ring is approximately approximately 1/2 of the phase
ring width on the objective.
I have done hundreds of tests with COL using numerous stands
and objectives from 1850's Victorian to modern together with tests
and dark field positions on condensers like the achromatic-aplanatic NA
1.4 from Zeiss and indeed many home made stops fitted to filter trays.
Experimenting with these I have always found an optimum width for
the illuminating ring, too thin and excessive reduction of illumination
together with artifacts introduced and this sample of the
condenser verges on that, so I remain unconvinced of the results but I
will persevere with it and possibly find combinations of
objectives and settings where it performs better.
Dry achromatic NA 0.9 turret phase condenser.
The condenser could take many years of use!
Compact Leica camera
Ideally suited to the later version
of the Ortholux
with built in field iris on the base this can still be used on the
older stand. Focusing the condenser can be
achieved by placing a thin opaque object on top of the glass
plate on the microscope base and bringing into focus. A swing out top
power objectives to be used. Mechanically the condenser works with
oblique illumination, bright field (H), dark field can be achieved with
the older Pv phase objectives but the annuli do not match so cannot be
used for phase...
This can be rectified by using the later 'Phaco' objectives
but I have not purchased them, interesting though the
annuli match my brother's Zeiss Neofluar phase objectives from the
Photomicroscope III as tested on ph2 position, 16x 0.4, 25x
0.6 & 40x 0.75 work well, I suspect that the ph3
position would work too for the higher power Zeiss's but this was not
Leitz dark field oil condenser NA 1.2-1.4.
Easy to use and
unassuming this is a favourite with me for COL on diatoms, ideally
suited to modern preparations as slide thickness will affect results.
Using a drop
of water the drop sitting nicely in the small concave dip of the glass
condenser top as it is offered up to the underside of the slide and
using a high performance objective like a Zeiss plan-apo 100x
NA 1.30 (DIN 160mm) oil
immersion superb results in COL can be achieved. The overall
characteristics of the COL illuminating ring was determined by choice of
objective and condenser immersion medium used, but in this case was
brilliant in its nature benefiting from the well computed optics
of the Zeiss and the visual image of subjects portrayed with noticeable
absence of flare or artifacts.
Recently I acquired a Klaus Kemp strew slide of Amphipleura pellucida in a high
refractive mount RI 1.9, thin cover slip and with 10x eyepieces (note the
viewing head has a 1.25x magnification factor) the striae were
portrayed with great contrast and definition whilst punctae within
limitations of eyepieces and my eyes, well defined.
The centering when
first used was found to be seized due to hardened grease in the mount
refurbishment works well and once set needs little adjustment on
further insertions into the microscope stand. I would have liked to
test the condenser with a Leitz fluorite NA 1.30 objective of the
period but unable to source at the current time.
'MIKAS' micro attachment for the Leica film camera body.
This came with the microscope and
occasionally they can be found at dealers or on eBay. The eyepiece is
slotted in the alloy ring at the base of the adapter after unscrewing
from the main body, only certain eyepieces can be used the older
OK, the newer ones won't fit. A focusing telescope is used which has
graticules marked. The unit is offered up to the 23mm camera port on
Ortholux and clamped in position. Different adapters can be screwed
onto the 39mm thread originally designed for Leica camera bodies, here
shown with an adapter for a Sony NEX mount digital camera.
A cable release allows speeds from 'T' & 'B' setting up to 1/125th
second, later 'MIKAS' attachments may differ in style and the highest
shutter speed used. The complex
'Compur' shutter mechanism also found on press cameras and many others of the
time is notorious now for not working on one setting or
another, this one is fine on all settings except 'T'.
cable release with long pin protrusion is required to operate the
mechanism successfully, the one which came with the adapter was
shown above is a short lead one from years ago hiding away
an old accessories box!
As yet I have not attempted
any digital camera work with the microscope, this article may be
followed up with another covering this in more detail.
The Leitz Ortholux is a fine
microscope built to standards not seen in the modern age, it would be
too expensive to produce and last far too long so wouldn't be cost
A good range of accessories were available originally although getting
harder to source now including a
sizable selection of objectives. The pitfalls
(and this is most noteworthy) must always be one of finding a good
sample that has not been abused
and relying on the experience, quality of checks and honesty from the
whether eBay or dealer in regards all is well with both stand,
It is becoming much harder to source 50 year old optics
whether Leitz, Zeiss or others that are in first class condition, free
of defects and no matter
what the fineries of any microscope it is only as good as the
eyepieces and condensers fitted, this is why many prefer to use more
Microscopy UK or their contributors.
the August 2010 edition of Micscape Magazine.
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