By Ian Walker. UK.
Continuing a series of articles about a 'classic' stand.
Introduction.
This article continues a series I have written in Micscape but rather than exploring the maintenance side this one concentrates on the history of LOMO and its connections with Carl Zeiss Jena together with my opinion of the optical and mechanical performance of the stand and objectives.
There has been much said over the years regarding the quality and suitability of the Biolam for routine amateur microscopy which in some circles has been derided as poor and unreliable and even regarded as a toy but from our combined experience of well over 30 years of use between my brother and me this is far from the truth. Dave purchased his first stand 28 years ago in 1978 and since then has added a number of accessories and objectives, it is still in regular use today having had very little maintenance carried out. I have had the opportunity many times to use this microscope whilst also buying, refurbishing and selling several cheap variants of the stand from eBay to learn about the different models and use the opportunity to write about simple methods of bringing back old and unused stands to good working order.
Some history.
Fig 3.
One version of the Carl Zeiss Stand 'L' 1934, the basic design used for the LOMO Biolam.
The connection between LOMO
[Leningrad Optical & Mechanical Enterprise] and Carl Zeiss is an
interesting and rather complex one. LOMO manufactured its first
microscope in 1934 but its history goes further far back to 1914 when
the factory first started producing
optical equipment for the Russian army.
By the mid 1930's the Carl Zeiss Jena factories in Germany were employing a very large work force of highly skilled engineers, technicians and auxiliary staff using very sophisticated manufacturing techniques for the time, over its long history the nature of microscopy would be radically changed by the mathematical theories and optical skills of Professors Abbe and Kohler and the manufacturing of new glass types by Dr. Otto Schott these documents and theories being continuously added to the library since the company was established by Carl Zeiss at the age of 30 in 1846. At the end of World War II in the historic Yalta Meeting Germany was to be divided into what we used to know as West and East Germany and the eastern block was to be administered by the Russians by agreement made between the allied countries, the Jena factory being in the eastern sector was therefore considered much use to them. Russia had lost many of its skilled personnel and machinery from the war and the German workers were initially pleased since they were led to believe the Russians wanted to continue production at the Jena factories but it was not long before a devastating decision was made by the Russian authorities to close the factories and move as much of the Jena equipment that was still in tact [and many of the workforce] to Russia the notice being given of closure and re-location at short notice in late October 1946.
However, this is only half the story since a number of weeks before the Russians reached Jena the Americans had arrived and also considered the plant and highly skilled workforce well worth keeping. The Americans knew Jena was going to fall to Russian administration under the agreement but they had little time to move equipment into the American - English zone what was to become West Germany before the Russians took over so to retain as much expertise as possible they questioned the directors, top scientists and all the key personnel who wished to move before the Russians arrived. So, together with many of the highest skilled workforce and virtually all the drawings, accumulated theory and design of the instruments together with as much of the most important machinery was transported over to the American zone.
Where did that leave Zeiss Jena in the future East Germany? Well, having lost a century of most valuable knowledge and the cream of the top designers and engineers and with only a fraction of the original workers and equipment not displaced either by the Americans or Russians they had to start all over again both in machinery and workforce but they did rebuild the factory and remained as a manufacturer of instruments continuing to be known as Zeiss Jena after much wrangling between various law courts who could still use the name 'Zeiss'. Zeiss of West Germany also known as Zeiss Oberkochen or Zeiss West continues to manufacture today under a unified Germany and is now simply known as 'Zeiss' whilst the name of Zeiss Jena has demised into the history books.
Most of the above is based on an excellent article 'The Story of Zeiss' by R. Winsby from the Manchester Microscopical & Natural History Society Newsletter May 1987.
Fig 1.
The Zeiss factories from the book 'Zeiss Microscopes' 1935.
Some of the earliest post-war LOMO microscopes are copies from the
pre-war Jena catalogue as you would expect since much of the
manufacturing plant was obtained by them but diversification over the
years have produced a number of new designs. However you only have to
look at many of the pre DIN objectives and accessories of older designs
like the Biolam to see a very strong resemblance even today to those
manufactured by Zeiss many years ago in their Jena workshops, indeed
the objectives
such as the apochromatic range are outwardly nearly identical to those
of Jena in the 1930's, the glass however is different the raw material
being sourced in Russia.
On this point I am awaiting an old Carl Zeiss Jena Stand 'F' fitted with a set of four apochromatic objectives three of which the 10x, 20x and 40x being of the same magnification and aperture to those shown in Fig 11. later in the article. The stand was built in the 1920's but the objectives are of the same design as the 1934 catalogue and this is going to form an article shortly on the comparison between the Zeiss and LOMO optics with pictures side by side showing the similarities between the two and notes on the difference optically [if any] between them. By the late 1930's this stand had lost favour to new designs like the 'L' stand with low slung focus controls and horizontal stage and doesn't appear in the 1937 catalogue.
Fig 2.
LOMO remained a rather secretive enterprise for many years after the war not only manufacturing microscopes but also optical equipment for the military. At this point in time I believe the factory based in St. Petersburg still employs thousands of skilled workers not only producing microscopes but many other optical equipments for medical, astronomical and consumer use. The LOMO name remains and a large range of optics is still offered for sale, indeed you can still buy the Biolam in the U.S. now called the Multiscope together with objectives very similar in appearance to those shown in this article but updated in specification to reflect requirements for improved flat field performance. The Multiscope is offered along with more sophisticated and expensive stands with DIN objectives together with microscopes for polarizing and fluorescence work.
By the mid 1930's the Carl Zeiss Jena factories in Germany were employing a very large work force of highly skilled engineers, technicians and auxiliary staff using very sophisticated manufacturing techniques for the time, over its long history the nature of microscopy would be radically changed by the mathematical theories and optical skills of Professors Abbe and Kohler and the manufacturing of new glass types by Dr. Otto Schott these documents and theories being continuously added to the library since the company was established by Carl Zeiss at the age of 30 in 1846. At the end of World War II in the historic Yalta Meeting Germany was to be divided into what we used to know as West and East Germany and the eastern block was to be administered by the Russians by agreement made between the allied countries, the Jena factory being in the eastern sector was therefore considered much use to them. Russia had lost many of its skilled personnel and machinery from the war and the German workers were initially pleased since they were led to believe the Russians wanted to continue production at the Jena factories but it was not long before a devastating decision was made by the Russian authorities to close the factories and move as much of the Jena equipment that was still in tact [and many of the workforce] to Russia the notice being given of closure and re-location at short notice in late October 1946.
However, this is only half the story since a number of weeks before the Russians reached Jena the Americans had arrived and also considered the plant and highly skilled workforce well worth keeping. The Americans knew Jena was going to fall to Russian administration under the agreement but they had little time to move equipment into the American - English zone what was to become West Germany before the Russians took over so to retain as much expertise as possible they questioned the directors, top scientists and all the key personnel who wished to move before the Russians arrived. So, together with many of the highest skilled workforce and virtually all the drawings, accumulated theory and design of the instruments together with as much of the most important machinery was transported over to the American zone.
Where did that leave Zeiss Jena in the future East Germany? Well, having lost a century of most valuable knowledge and the cream of the top designers and engineers and with only a fraction of the original workers and equipment not displaced either by the Americans or Russians they had to start all over again both in machinery and workforce but they did rebuild the factory and remained as a manufacturer of instruments continuing to be known as Zeiss Jena after much wrangling between various law courts who could still use the name 'Zeiss'. Zeiss of West Germany also known as Zeiss Oberkochen or Zeiss West continues to manufacture today under a unified Germany and is now simply known as 'Zeiss' whilst the name of Zeiss Jena has demised into the history books.
Most of the above is based on an excellent article 'The Story of Zeiss' by R. Winsby from the Manchester Microscopical & Natural History Society Newsletter May 1987.
Fig 1.
The Zeiss factories from the book 'Zeiss Microscopes' 1935.
On this point I am awaiting an old Carl Zeiss Jena Stand 'F' fitted with a set of four apochromatic objectives three of which the 10x, 20x and 40x being of the same magnification and aperture to those shown in Fig 11. later in the article. The stand was built in the 1920's but the objectives are of the same design as the 1934 catalogue and this is going to form an article shortly on the comparison between the Zeiss and LOMO optics with pictures side by side showing the similarities between the two and notes on the difference optically [if any] between them. By the late 1930's this stand had lost favour to new designs like the 'L' stand with low slung focus controls and horizontal stage and doesn't appear in the 1937 catalogue.
Fig 2.
Carl Zeiss Stand 'FZE' 1934,
this is similar to the stand I am waiting for. Zeiss always liked to
provide fully equipped stands for different purposes including standard
research, bacteriology etc this was one of their top stands with quick
release monocular - binocular tubes and a full set of eight
apochromatic objectives together with a special centring aplanatic NA
1.4 3 element slide-in oblique condenser. The 'F' Stand came in several
versions this being the best equipped, mine is lower in the range
having a factory pre-centred and removable aplanatic oblique condenser
and being of earlier vintage an angular foot design not curved as shown
above but otherwise the main features of the microscope are the same.
The price given for the 'FZE' including objectives in 1934 was
£220 3s 6d.... quite a large sum of money! The apochromatic
objectives
reflecting their sophisticated and delicate build being very expensive,
the 60x NA 1.4 oil immersion alone was £30 4s which is more than
some of the complete boxed microscope packages being sold by British
manufacturers at the time. As a guide from the website Economic History
Services website www.eh.net, £220 using retail price index
computed to 2004 prices is around £10,000 whilst for the same year
calculated based on average earnings is around £37,000!
LOMO remained a rather secretive enterprise for many years after the war not only manufacturing microscopes but also optical equipment for the military. At this point in time I believe the factory based in St. Petersburg still employs thousands of skilled workers not only producing microscopes but many other optical equipments for medical, astronomical and consumer use. The LOMO name remains and a large range of optics is still offered for sale, indeed you can still buy the Biolam in the U.S. now called the Multiscope together with objectives very similar in appearance to those shown in this article but updated in specification to reflect requirements for improved flat field performance. The Multiscope is offered along with more sophisticated and expensive stands with DIN objectives together with microscopes for polarizing and fluorescence work.
Fig 3.
One version of the Carl Zeiss Stand 'L' 1934, the basic design used for the LOMO Biolam.
LOMO Biolam, some cautionary notes
to new users.
One thing more than anything else
lets older samples of the microscope down is the Russian grease which
has caused more problems over the years than just about anything else;
it has the consistency and look of thick green axle grease and
appears to
be somewhat acidic spoiling the finish of brass and aluminium sliders
and seizing components if left for years without attention but I have
not found so far a stand or parts which could not be worked on and
brought back into working order with the minimum amount of household tools and simple cleaning methods. It is not my intention to
reiterate what I have already discussed in detail in my previous
articles; regarding this matter just follow the links provided at the
end of the article.
The older stands require an external light either by LOMO [not easy to source now except for the overpriced OI-35] or of your own making but I don't consider this a disadvantage since it gives me the flexibility of using different light sources like LED and fluorescent which I like to design and also helps new users of the microscope to go and pick up a good microscopy book and learn a lot more about setting up the lighting compared to a modern stand. At its simplest a good quality 60 watt angle-poise lamp with pearl bulb and shade can provide adequate illumination for most purposes.
It is a moving limb design so more caution has to be used when adding heavier items like the trinocular head or camera attachments so getting the coarse focus friction and lubrication right is important to prevent damage to slides or objectives. This in its right own cannot be called a negative feature since many designs are of this type including the Wild M20 and models from Carl Zeiss and Ernst Leitz from the early 20th century. You could say it is outdated now but LOMO provide higher priced stands with fixed limb if you wish to pay extra but with care and attention to operating practices there is not much to choose between moving stage and moving limb for focusing.
The older stands require an external light either by LOMO [not easy to source now except for the overpriced OI-35] or of your own making but I don't consider this a disadvantage since it gives me the flexibility of using different light sources like LED and fluorescent which I like to design and also helps new users of the microscope to go and pick up a good microscopy book and learn a lot more about setting up the lighting compared to a modern stand. At its simplest a good quality 60 watt angle-poise lamp with pearl bulb and shade can provide adequate illumination for most purposes.
It is a moving limb design so more caution has to be used when adding heavier items like the trinocular head or camera attachments so getting the coarse focus friction and lubrication right is important to prevent damage to slides or objectives. This in its right own cannot be called a negative feature since many designs are of this type including the Wild M20 and models from Carl Zeiss and Ernst Leitz from the early 20th century. You could say it is outdated now but LOMO provide higher priced stands with fixed limb if you wish to pay extra but with care and attention to operating practices there is not much to choose between moving stage and moving limb for focusing.
Some good points.
On used microscopes, gains and pitfalls.
These notes are from personal experience, you may have very different views.
Like the original Zeiss 'L' stand
the Biolam comes in several variants
and optional accessories depending on the vintage and price of the
microscope these include:
Fig 4.
Zeiss simplified mechanical stage 'A' 1934, similar to Fig 5. below.
Fig 5.
LOMO rotating stage fitted with mechanical stage control CT-12.
Fig 6.
Zeiss mechanical stage control 1934.
Fig 7.
Original Zeiss large mechanical stage 'E' 1934.
Most of these options are still available either new from outlets in Germany / U.S. or in small quantities from RAF Camera or eBay, you may have to wait a while but they will turn up. The latest stand also has built in 20 Watt halogen illumination. So we can see from this list we can have bright-field, dark-field [low and high power], phase contrast and with some simple home made accessories Rheinberg and polarized light microscopy... not bad for a modest stand. There is even specialized fluorescence and epi-illumination options on the modern stand. More importantly most of these options are quite affordable after you purchase the stand especially if you buy used, compare this to some of the prices you may have to pay to get apochromatic objectives or aplanatic condenser from Leica or Olympus for instance.
- Plastic rectangular stage with stage clips, this is the simplest and most often seen on ebay.
- Rotating stage with clips or detachable mechanical controls, main components of metal but finished in dense plastic as shown in Fig 5. below.
Fig 4.
Zeiss simplified mechanical stage 'A' 1934, similar to Fig 5. below.
Fig 5.
LOMO rotating stage fitted with mechanical stage control CT-12.
Fig 6.
Zeiss mechanical stage control 1934.
- Large mechanical stage with built in controls based on the design of Zeiss Stage 'E' as shown in Fig 7. these are not so common and fitted to older stands.
Fig 7.
Original Zeiss large mechanical stage 'E' 1934.
- Modern large rectangular stage with drop down
controls, this is the one typically found on the LOMO stand in the U.S.
- Clock-work or 'base disc' fine focus mechanism depends on age of the stand, the newer ones all use the 'disc', older ones either clock-work or 'disc'.
Typical accessories.
- Phase contrast set supplied in a wooden box with achromatic phase objectives.
- Aplanatic NA 1.4 condenser with oblique slider control supplied in a wooden box.
- High power dark-field condenser supplied in wooden box matches specific objectives from the LOMO range.
- Monocular vertical/inclined, binocular, trinocular and photographic heads with photo eyepieces.
- A large selection of pre DIN achromatic and apochromatic objectives [use with compensating eyepieces] derived from the original Zeiss Jena designs.
Most of these options are still available either new from outlets in Germany / U.S. or in small quantities from RAF Camera or eBay, you may have to wait a while but they will turn up. The latest stand also has built in 20 Watt halogen illumination. So we can see from this list we can have bright-field, dark-field [low and high power], phase contrast and with some simple home made accessories Rheinberg and polarized light microscopy... not bad for a modest stand. There is even specialized fluorescence and epi-illumination options on the modern stand. More importantly most of these options are quite affordable after you purchase the stand especially if you buy used, compare this to some of the prices you may have to pay to get apochromatic objectives or aplanatic condenser from Leica or Olympus for instance.
The stand.
Here is a list of the objectives my brother has, the numerical apertures not listed are standard for the type, the machining and finish are uniformly excellent:
3.5x plan, 8x, 9x, 20x, 40x, 40x NA 0.75 and 85x NA 1.0 water immersions, the latter with correction collar and 90x oil immersion achromats.
10x NA 0.3, 20x, 40x and 90x phase achromats but not shown in the pictures since they have very similar appearance to the standard achromat range.
Fig 9.
Typical LOMO achromatic objectives, the 40x NA 0.65 is the best achromat in this standard numerical aperture I have come across.
Fig 10.
40x NA 0.75 and 85x NA 1.0 water immersion objectives, 85x let down by stiff collar on our sample making it difficult to use.
Fig 8. below shows a
collection of LOMO apochromatic objectives, the 10x NA 0.3, 20x NA
0.65, 60x NA
0.7-1.0 oil immersion for high power dark-field and 40x NA 0.95 dry
correction collar. An old 90x NA 1.30 oil immersion
is the latest to be added and is on order so has not been tested but I
will add a mention in a future article if particularly good or bad.
Fig 11.
10x NA 0.3, 20x NA 0.65, 60x NA 0.7-1.0 diaphragm [DF], 40x NA 0.95 [CC].
Now to my favourites the apochromatics. All our samples are optically excellent my favourites being the 20x NA 0.65 and 40x NA 0.95 these would normally be used with compensating eyepieces marked on the LOMO as 7K or 10K etc for residual colour correction. The 20x gives superb dark-field results on my old brass scope with the supplied stop providing very bright subjects on a velvety black background unobtainable on a lot of older achromatic objectives which can give a 'foggy' appearance for this magnification. With its high NA it also gives a real crispness to bright-field subjects and needs higher power eyepieces to reveal hidden detail not seen with the 7x eyepieces.
The 40x NA 0.95 can give stunning results on modern slide preparations but is let down by the correction collar which runs very stiff indeed in colder weather due to hardened grease but I often use this on my Edwardian scope fitted with its rack and pinion monocular tube so I can correct for different cover thickness by tube length rather than correction collar which I find more convenient anyway leaving the correction set to 0.17mm on the objective. As with objectives from any manufacturer producing them in large quantities there will be variations in output so there is the possibility of an occasional poor sample something I have noted with more modern Zeiss 40x achromatic objectives which from my samples both for 160mm and infinity corrected seem to under perform.
A mention must be made also of the 60x NA 0.7-1.0 with internal diaphragm. This objective has been specially made for the high power dark-field condenser but with diaphragm set to 1.0 it gives excellent results in bright-field and is a nice intermediate power between the 40x dry and 90x oil immersion objectives. I am awaiting the original Zeiss Jena dark-field condenser for my Zeiss microscope which I hope will be cross-platform and also fit the LOMO stand. I will possibly write an article in the future on the results obtained and some sample images.
The LOMO apochromatic objectives are based on early 20th century Zeiss designs, good field flatness could not be achieved only at the expense of reducing aperture which in those days was deemed totally unacceptable for apochromatics the highest numerical apertures always being strived for.
The LOMO aplanatic condenser.
Fig 12.
Aplanatic NA 1.4 oblique condenser with alternative NA 0.3 top element above.
The older stands in general are best
described 'workmanlike'
not exuding the paint finish of say a Wild M20 or Zeiss Standard but
its original price
reflects this being a fraction of the
cost of an M20 when it was new. It does the job though and it is well
worth at some
point removing
the original grease from the coarse focus sliders if it becomes stiff
and lumpy rather than carrying on, you will be
extending the
life of the instrument and it will feel so much better with a modern
lubricant like those supplied by Nye. The same with the rotating stage
which is of particular problem with some older samples, a tip here
after meticulously cleaning all grease and hardened deposits from the
rotating surfaces is do not grease again but use a light to medium
viscosity oil, greasing it and the rotation becomes
stiff and thoroughly unpleasant to use but lightly oil all rotating
surfaces on re-assembly will provide a 'glide' stage with the motion
and feel of any good model on the market. The mechanical
stage controls both as a detachable unit [CT-12] and as part of the
more
complex rotating stage can be adjusted for slack but do tend to loosen
over extended use requiring re-adjusting from time to time but from our
samples seem to work well with the original grease surprisingly and
haven't needed much work over the years.
Fig 8.
LOMO Biolam with binocular head and Abbe condenser from the late 1970's.
In contrast to the rather utilitarian paint finish the mechanics lurking within the stand are very good with solid castings and engineering with few plastic parts critical in the construction to crack or break over the years. Where plastic is used in the condenser height control for instance it is because the action should be of a light and delicate nature not requiring sufficient force to require larger brass fittings. The older clock-work fine focus mechanisms being embedded well within the body of the stand usually doesn't cause any problems and our two stands are free from any undue play or back-lash. If you have to work on it and I think this is based on the same mechanism as the Zeiss Jena stand 'L' is after cleaning any debris or grease that shouldn't be in the mechanism anyway is to use no lubrication on any of the small delicate cogs and teeth, they should run dry.
Fig 8.
LOMO Biolam with binocular head and Abbe condenser from the late 1970's.
In contrast to the rather utilitarian paint finish the mechanics lurking within the stand are very good with solid castings and engineering with few plastic parts critical in the construction to crack or break over the years. Where plastic is used in the condenser height control for instance it is because the action should be of a light and delicate nature not requiring sufficient force to require larger brass fittings. The older clock-work fine focus mechanisms being embedded well within the body of the stand usually doesn't cause any problems and our two stands are free from any undue play or back-lash. If you have to work on it and I think this is based on the same mechanism as the Zeiss Jena stand 'L' is after cleaning any debris or grease that shouldn't be in the mechanism anyway is to use no lubrication on any of the small delicate cogs and teeth, they should run dry.
Optics.
Here is a list of the objectives my brother has, the numerical apertures not listed are standard for the type, the machining and finish are uniformly excellent:
3.5x plan, 8x, 9x, 20x, 40x, 40x NA 0.75 and 85x NA 1.0 water immersions, the latter with correction collar and 90x oil immersion achromats.
10x NA 0.3, 20x, 40x and 90x phase achromats but not shown in the pictures since they have very similar appearance to the standard achromat range.
Fig 9.
Typical LOMO achromatic objectives, the 40x NA 0.65 is the best achromat in this standard numerical aperture I have come across.
Of the achromat objectives listed
most of the achromats are competent for their
class but a
special mention must be for the 3.5x and 90x NA 1.25 oil immersion. The
3.5x with LOMO none compensating eyepieces provides as near 100% plan
across the field as one could desire and provides bright sharp images
specially suited to botanical, mineral and rock sections with the
rotating stage
version of the stand.
Only a few weeks ago tests were done with the achromatic 90x oil immersion with the aplanatic condenser 'watered-up' to the bottom of the slide with a strew of the diatom Amphipleura pellucida mounted in sirax comparing this with the Zeiss Photomic III with achromatic-aplanatic NA 1.4 condenser oiled to the slide using a Zeiss 100x NA 1.25 achromat and phase neofluar NA 1.30 objectives the scopes being side by side. The test was interesting in that the humble LOMO setup provided an excellent account of itself with markings of the diatom clearly shown with a modest amount of oblique illumination and produced little in the way of residual colour from the objective producing a clear and most satisfying image. On the other hand the image from the Zeiss phase Neofluar in brightfield with oblique illumination created a rather unpleasant colour caste on the markings of green-purple [depending on focus] and was considered unsatisfactory whilst the 100x achromat was deemed satisfactory. The 'X' 'Y' controls on our mechanical stage are a little 'jumpy' on the LOMO at 1000x and above magnification but still perfectly usable whilst the Zeiss Photomic stage controls were smoother but no means faultless.
Of the objectives running in phase contrast my favourite is the 10x NA 0.3 which gives a bright crisp image whilst looking at pond samples and gives particularly pleasing images on common subjects like spirogyra, the others are competent but not in the same class as Wild's phase fluotars with high numerical aperture which really excel in this area, the Wild 10x NA 0.45 and 20x NA 0.60 could hardly be bettered in this respect provided field flatness is of no concern to the user.
Only a few weeks ago tests were done with the achromatic 90x oil immersion with the aplanatic condenser 'watered-up' to the bottom of the slide with a strew of the diatom Amphipleura pellucida mounted in sirax comparing this with the Zeiss Photomic III with achromatic-aplanatic NA 1.4 condenser oiled to the slide using a Zeiss 100x NA 1.25 achromat and phase neofluar NA 1.30 objectives the scopes being side by side. The test was interesting in that the humble LOMO setup provided an excellent account of itself with markings of the diatom clearly shown with a modest amount of oblique illumination and produced little in the way of residual colour from the objective producing a clear and most satisfying image. On the other hand the image from the Zeiss phase Neofluar in brightfield with oblique illumination created a rather unpleasant colour caste on the markings of green-purple [depending on focus] and was considered unsatisfactory whilst the 100x achromat was deemed satisfactory. The 'X' 'Y' controls on our mechanical stage are a little 'jumpy' on the LOMO at 1000x and above magnification but still perfectly usable whilst the Zeiss Photomic stage controls were smoother but no means faultless.
Of the objectives running in phase contrast my favourite is the 10x NA 0.3 which gives a bright crisp image whilst looking at pond samples and gives particularly pleasing images on common subjects like spirogyra, the others are competent but not in the same class as Wild's phase fluotars with high numerical aperture which really excel in this area, the Wild 10x NA 0.45 and 20x NA 0.60 could hardly be bettered in this respect provided field flatness is of no concern to the user.
Fig 10.
40x NA 0.75 and 85x NA 1.0 water immersion objectives, 85x let down by stiff collar on our sample making it difficult to use.
The 40x NA 0.75 achromatic water
immersion is a good objective but it gets little use since the
numerical aperture is of insufficient gain most of the time to water up
the slide. The tendency is to use the 40x NA 0.65 dry achromat being an
excellent all rounder easily resolving Pleurosigma angulatum without
oblique and if further aperture is required moving on to the 40x NA
0.95 dry apo or oil immersion objectives.
The 85x NA 1.0 WI on the other hand is an objective to use when you wish to avoid oiling slides providing good detail and contrast on most diatom structures however its correction collar is very stiff [typical for LOMO] and so the tendency is to leave it set on 0.17mm and use modern preparations where cover slips are of more uniform thickness. I still think the 90x NA 1.25 oil immersion is the better objective giving crisper and better definition to more difficult subjects and is very forgiving of Victorian slides.
The 85x NA 1.0 WI on the other hand is an objective to use when you wish to avoid oiling slides providing good detail and contrast on most diatom structures however its correction collar is very stiff [typical for LOMO] and so the tendency is to leave it set on 0.17mm and use modern preparations where cover slips are of more uniform thickness. I still think the 90x NA 1.25 oil immersion is the better objective giving crisper and better definition to more difficult subjects and is very forgiving of Victorian slides.
Fig 11.
10x NA 0.3, 20x NA 0.65, 60x NA 0.7-1.0 diaphragm [DF], 40x NA 0.95 [CC].
Now to my favourites the apochromatics. All our samples are optically excellent my favourites being the 20x NA 0.65 and 40x NA 0.95 these would normally be used with compensating eyepieces marked on the LOMO as 7K or 10K etc for residual colour correction. The 20x gives superb dark-field results on my old brass scope with the supplied stop providing very bright subjects on a velvety black background unobtainable on a lot of older achromatic objectives which can give a 'foggy' appearance for this magnification. With its high NA it also gives a real crispness to bright-field subjects and needs higher power eyepieces to reveal hidden detail not seen with the 7x eyepieces.
The 40x NA 0.95 can give stunning results on modern slide preparations but is let down by the correction collar which runs very stiff indeed in colder weather due to hardened grease but I often use this on my Edwardian scope fitted with its rack and pinion monocular tube so I can correct for different cover thickness by tube length rather than correction collar which I find more convenient anyway leaving the correction set to 0.17mm on the objective. As with objectives from any manufacturer producing them in large quantities there will be variations in output so there is the possibility of an occasional poor sample something I have noted with more modern Zeiss 40x achromatic objectives which from my samples both for 160mm and infinity corrected seem to under perform.
A mention must be made also of the 60x NA 0.7-1.0 with internal diaphragm. This objective has been specially made for the high power dark-field condenser but with diaphragm set to 1.0 it gives excellent results in bright-field and is a nice intermediate power between the 40x dry and 90x oil immersion objectives. I am awaiting the original Zeiss Jena dark-field condenser for my Zeiss microscope which I hope will be cross-platform and also fit the LOMO stand. I will possibly write an article in the future on the results obtained and some sample images.
The LOMO apochromatic objectives are based on early 20th century Zeiss designs, good field flatness could not be achieved only at the expense of reducing aperture which in those days was deemed totally unacceptable for apochromatics the highest numerical apertures always being strived for.
The LOMO aplanatic condenser.
Fig 12.
Aplanatic NA 1.4 oblique condenser with alternative NA 0.3 top element above.
The 2 element aplanatic lens
configuration provides enough aperture with a drop of water applied
between its upper surface and the bottom of the slide for the 90x oil
immersion. My brother has found this method works well and had no
problems with leakage into the elements also saving the messy business
of removing oil every time you wish to change slides or change to
lower power objectives. This appears not to be a direct copy of the
1930's Zeiss design which uses 3 elements but in other
respects they are quite similar. We have had a problem with the sliding
surfaces and diaphragm becoming stiff over the years and needing a good
clean
and slider re-lubricating but this
is a one-off procedure and needs no more maintenance for many years. If
your condenser diaphragm needs to be dismantled because of jammed
leaves or stiff
operation due to an old thick application of grease they should be
individually and carefully
cleaned and re-assembled dry. A swing-out filter tray is supplied
beneath the diaphragm.
The LOMO Abbe phase condenser.
Fig 13.
The phase telescope fits in the velvet lined slot at the bottom and not shown.
Fig 13.
The phase telescope fits in the velvet lined slot at the bottom and not shown.
This LOMO phase condenser comes as a
boxed kit with supplied optics, the rings being matched to specific
objectives unlike
Zeiss which are labeled positions I, II, III and can take a
variety of different objectives for each ring. I like the simple light
weight design with smooth easy rotation on our sample and nice positive
click stops and well made glass phase positions with thickly painted
phase rings, no delamination
problems here. Centring of the rings is achieved with two simple side
adjusters and comes with swing-out filter tray and phase telescope.
Fig 14.
Phase condenser in position on the microscope with phase objectives on the turret.
Compare this to phase condensers from Zeiss like the one shown on the right in Fig 15. which have had phase rings come off from the glass, seized diaphragms [grease] and very stiff rotation [grease], each one I have owned has needed work doing on them before being usable. A much more modern Zeiss aplanatic-achromatic condenser that my brother bought recently had top glass elements full of oil, considering its specifically designed for oil immersion suggests the seal was not very good and since it was sold as checked and working.... buyer beware.
Fig 15.
Comparison between LOMO and an old Zeiss aplanatic NA 0.63 LWD phase condenser.
Fig 14.
Phase condenser in position on the microscope with phase objectives on the turret.
Compare this to phase condensers from Zeiss like the one shown on the right in Fig 15. which have had phase rings come off from the glass, seized diaphragms [grease] and very stiff rotation [grease], each one I have owned has needed work doing on them before being usable. A much more modern Zeiss aplanatic-achromatic condenser that my brother bought recently had top glass elements full of oil, considering its specifically designed for oil immersion suggests the seal was not very good and since it was sold as checked and working.... buyer beware.
Fig 15.
Comparison between LOMO and an old Zeiss aplanatic NA 0.63 LWD phase condenser.
Tube options.
The standard binocular tube with its
1.5x mag factor is good with well collimated optics and provides
relaxing images, a difference in
brightness can be seen when looking through the tubes singly but
this is typical of the design and I have seen this in several other
microscopes both from English makers and Germany especially between the
1950's - 1970's.
The angled monocular I can highly
recommend, this simple tube giving substantially brighter images than
the binocular head but remember the binocular has a 1.5x magnification
factor due to its design so to get the same magnification for a given
objective you would require say 7x eyepieces on the
binocular and 10x on the monocular but for critical work for
short periods I
think this is sometimes the best option.
The simple vertical tube has no optics of its own and can be used with or without an eyepiece being mainly used with video or still cameras.
The trinocular attachment shown in Fig 16. with built in magnification changer and Bertrand lens position is rather bulky and heavy and I personally think unbalances the stand - the whole thing becoming rather unwieldy, although Dave bought an old second hand one to try some time ago it has had little use preferring the simple vertical tube and a camera setup like the Sony S75 digital camera with T2 attachment to accept an eyepiece and Nikon reversed lens.
Fig 16. and Fig 17.
LOMO trinocular and photographic attachments.
The monocular photo attachment shown in Fig 17. is much lighter than the trinocular head and has an angled focusing eyepiece tube to obtain parfocality with the vertical attachment to take T2 mounts etc but in the old days was primarily designed for the Zenith camera back. Again, an old second hand one was bought some time ago but the fit and finish on our sample doesn't seem to be as good as the rest of the LOMO accessories and is rather crude.
The simple vertical tube has no optics of its own and can be used with or without an eyepiece being mainly used with video or still cameras.
The trinocular attachment shown in Fig 16. with built in magnification changer and Bertrand lens position is rather bulky and heavy and I personally think unbalances the stand - the whole thing becoming rather unwieldy, although Dave bought an old second hand one to try some time ago it has had little use preferring the simple vertical tube and a camera setup like the Sony S75 digital camera with T2 attachment to accept an eyepiece and Nikon reversed lens.
Fig 16. and Fig 17.
LOMO trinocular and photographic attachments.
The monocular photo attachment shown in Fig 17. is much lighter than the trinocular head and has an angled focusing eyepiece tube to obtain parfocality with the vertical attachment to take T2 mounts etc but in the old days was primarily designed for the Zenith camera back. Again, an old second hand one was bought some time ago but the fit and finish on our sample doesn't seem to be as good as the rest of the LOMO accessories and is rather crude.
On used microscopes, gains and pitfalls.
These notes are from personal experience, you may have very different views.
Sometimes I see the argument don't
buy LOMO buy a second-hand Zeiss, Wild etc
they are more reliable. With many stands and parts of stands coming up
frequently on eBay there is as much chance getting a poorly maintained
Zeiss which may have delaminating optics or faulty mechanics as there
is getting a poor example of a LOMO Biolam. At the typical low price of
£60 - £120 for a second hand LOMO if there is a problem
chances are with a
little work and minimum outlay it can be brought back to good order.
Zeiss sadly there is a nasty affliction going on in eBay recently were some sellers are reducing good complete stands to boxes of disembowelled parts to squeeze the last few dollars out of buyers; this means fewer and fewer good stands will be available for microscopists in the future.
Zeiss between the 1960's and 1970's produced thousands of objectives that are now delaminating. This of course does not include DIC prisms, sliders and polarizers afflicted with the same problem. I have yet to see a LOMO objective that has delaminated.
Zeiss made phase rings for their older condensers that had a tendency to flake or fall off.
LOMO is not alone in the grease problem, I have found Zeiss condenser and field diaphragms seized, phase condenser mechanics seized and correction collars on objectives very stiff and difficult to operate.
Wild used plastic for some of the cogs in their mechanical stages which may crack as they grow older with spares not easy to obtain and the stands themselves are not as straightforward to work on being a more complex design than LOMO.
Nikon used plastic gears in some of their old microscopes and these also had a tendency to crack, be broken by careless use or wear out, buy one of these stands and you may have trouble getting it repaired.
In the secondhand market the point I am trying to make is just because it's called Zeiss or Wild etc, the names we are supposed to trust for quality and reliability don't expect a trouble free ride when the delivery man knocks on your door with your microscope.
Do I hear the word 'dealer' being mentioned? Buy from a dealer, they check everything before dispatch right and sell you a nice working microscope. Well, yes and no from my experience, I have had some very good equipment from dealers both in the U.K. and abroad but I have also come across optics and mechanics that should have been checked more thoroughly before dispatch together with packing of items which has been very poor on occasion and you still have the problem of sorting it out especially if ordered from overseas.
So now we come full circle back to the LOMO Biolam. A stand which you can easily work on without detailed drawings learning about the microscope as you go along together with engineering of brass and aluminium. One which you can make simple parts for yourself and a system that is still supported after all these years with objectives and accessories. I have used and refurbished a good number of different scopes spanning 150 years from early Victorian to modern Leica and Zeiss infinity but the Biolam has stood the test of time, enough said.
Zeiss sadly there is a nasty affliction going on in eBay recently were some sellers are reducing good complete stands to boxes of disembowelled parts to squeeze the last few dollars out of buyers; this means fewer and fewer good stands will be available for microscopists in the future.
Zeiss between the 1960's and 1970's produced thousands of objectives that are now delaminating. This of course does not include DIC prisms, sliders and polarizers afflicted with the same problem. I have yet to see a LOMO objective that has delaminated.
Zeiss made phase rings for their older condensers that had a tendency to flake or fall off.
LOMO is not alone in the grease problem, I have found Zeiss condenser and field diaphragms seized, phase condenser mechanics seized and correction collars on objectives very stiff and difficult to operate.
Wild used plastic for some of the cogs in their mechanical stages which may crack as they grow older with spares not easy to obtain and the stands themselves are not as straightforward to work on being a more complex design than LOMO.
Nikon used plastic gears in some of their old microscopes and these also had a tendency to crack, be broken by careless use or wear out, buy one of these stands and you may have trouble getting it repaired.
In the secondhand market the point I am trying to make is just because it's called Zeiss or Wild etc, the names we are supposed to trust for quality and reliability don't expect a trouble free ride when the delivery man knocks on your door with your microscope.
Do I hear the word 'dealer' being mentioned? Buy from a dealer, they check everything before dispatch right and sell you a nice working microscope. Well, yes and no from my experience, I have had some very good equipment from dealers both in the U.K. and abroad but I have also come across optics and mechanics that should have been checked more thoroughly before dispatch together with packing of items which has been very poor on occasion and you still have the problem of sorting it out especially if ordered from overseas.
So now we come full circle back to the LOMO Biolam. A stand which you can easily work on without detailed drawings learning about the microscope as you go along together with engineering of brass and aluminium. One which you can make simple parts for yourself and a system that is still supported after all these years with objectives and accessories. I have used and refurbished a good number of different scopes spanning 150 years from early Victorian to modern Leica and Zeiss infinity but the Biolam has stood the test of time, enough said.
There is no longer a U.K. or European
distributor of LOMO microscopes but detailed information on the LOMO
range can be found at LOMO America
whilst the microscopes can be purchased at the U.S. dealer OpticsPlanet
[a typical stand with drop down controls and 20W lamp being $495, sadly
import duty and VAT for the U.K. mean this works out more expensive but
still a good scope for the money]. Also
there is a European supplier of LOMO objectives and
accessories in
Germany.