When was the golden age of Microscope hardware, and what Scopes from that age have survived the test of time

[Gatorengineer64]

Talking here about binocular scopes. Thinking that the answers I am going to get are going to be similar to cameras the The late 60s to the early 80s.... when there was still QC and plastic wasn't a preferred material....

A following is what objectives from that time are still sound by today's standards

[BramHuntingNematodes]

1920 to around 1950. After that they started making scopes gray instead of black and it all went to pot.

[MicroBob]

1920 to around 1950. After that they started making scopes gray instead of black and it all went to pot.

The german manufacturers stayed with black as the most common colour until the mid-60s, some even longer.

My impression is that the admiration for microscopes slowly became less around the mid-60s and economy got more influence on design decisions. On the other hand side some good developments in this time led to better microscopes, easier to use, less maintenance, more ergonomic eyepieces, plan objectives, DIC...

Which are the long lasting ones? I would put his question the other way round - what should I avoid?
Generally most microscopes will need a full service after this time and the amount of work and the complexity can be very different.
Mechanically the most robust will be the Zeiss West Standard RA and 14-18 with the steel ball planetary fine focus gear. Zeiss West optics have more problems with delamination than other brands, though one might have a wrong impression because of the high numbers Zeiss microscopes were made and the above average complexity of the optics. A simple achromat doesn't have many cemented lens group so delamination is less of a problem than with Zeiss Planapos with 15 or more lenses. Leitz optics of the same complexity and time are less prone to delamination though. Only the Leitz Plan(apo) 100:1 1,32 is very prone to delamination.

In the end individual condition will be more important then the general dependability of the model....


Bob

[Roldorf]

Now !!!!!
In your so called golden age I wouldn't have been able to afford one.

[apochronaut]

Once microscopes started to be primarily made of aluminum , there seemed to be a bit of a change in the precision balance and stability, while at the same time being capable of bigger and better things optically. Objective bodies continued as brass but many of the castings not. AO continued to make the Spencer # 5 large research stand, first introduced in the early 30's until 1955, an all brass, very stable, conventional horseshoe, low fine focus stand weighing in at around 25 lbs. It was normally fitted with 4 apochromats and a fine focus fitted 1.4 N.A. achromat condenser with an integrated oblique diaphragm. After 1955 the apochromats were allocated to the aluminum bodied Apostar. In it's heyday the #5 reputedly cost about as much as a small house.

[Chris Dee]

Early 1970's IMO. Usability and ergonomics got more attention, engineering and quality control was good, plastics not generally used in critical areas (some exceptions).
Styling can be questionable though.
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[Scarodactyl]

For what I do the late 80s and early 90s provide some of the best kit: wafer inspection and measuring scopes, surplused for pennies.
What's best will always depend on priorities anyway. Stereo scopes have had a few different peaks, depending on if you are focused more on build quality or optical specs (and which specs).

[PeteM]

The question probably needs to be divided into three parts; the stands, the illumination systems, and the optics.

1) There haven't been many technological advances in focusing mechanisms in many decades. Ball and roller bearings got a bit better and cheaper. The biggest contributions of new technology has been to make stands cheaper and many early versions of this got it wrong at first. The early plastic focusing gears, now often split in two, are an example. I'd say Zeiss from the Standard era, Leitz from the gray scopes era (superb fine focus) and then the early white scopes (longer range fine focus), Olympus from the BH2 era, and Nikon from the Labophot/Optiphot era (minus the plastic parts) meet every modern need and with the same inherent reliability as those old black bodied classics. Stands from a hundred years ago through to the 21st century can all be quite reliable. The modern trend has been cost reduction, sometimes at the expense of quality and reliability.

2) The sun and mirrors were reliable for illumination, but not exactly state of the art. The first tungsten bulbs were dim. The first tungsten-halogen bulbs often ran hot and their power supplies were large and (decades later) prone to failure. Most of the 100 watt halogen systems from the 80's on are excellent. Modern switching power supplies and the latest higher power LEDS are now surpassing them and at increasingly affordable prices.

3) Optics have significantly improved with computer-aided design, CNC lens grinding, and modern coatings. There were excellent manually designed objectives from decades before, but not every objective in a series was great. In addition they tend to have small fields of view, low contrast, and sometimes problems with delamination. Earliest effective computer ray tracing programs I can recall were from the late 1960's. By the late 1970's we had somwhat wider fields of view and better lens coatings. Those objectives still provide excellent images if in good shape. Today it's possible to get objectives with extremely wide plan fields of view, corrections across most of the spectrum, and options to see deep into the UV and infrared ranges. CNC lens grinding has lowered the cost of production. Digital processing is now providing yet another technological revolution. So far we have digital imaging, focus stacking, chromatic corrections and other post-processing tricks. The future likely holds further advances - spurred by developments behind a billion cell phone cameras, vision systems, and the like.

To me, all this suggests the best buy is a robust stand from the 70's to 90's with a really good and long range fine focus for focus stacking. Plus an illumination system with at least a 20 watt halogen lamp and/or easily upgradeable to LED. Plus a stand capable of hosting modern optics and easily attaching a digital camera.

[Dubious]

For the masses, it was probably during the manufacturing boom after WWII and before television had completely taken over as the household source of wonder. Otherwise, I would nominate the 1600s, when some monarchs actually traveled to visit humble microscope makers.

[farnsy]

The bodies of microscopes from 50 years ago had gears and things that were really heavy duty. Or at least, the ones that are still around today were robust in that respect.

In most cases, bodies are not the big thing, though. There are gears that break occasionally in first generation plastic stuff and you can't as easily break down a door with a modern microscope, but under normal use, microscopes are not high impact items. Today's microscopes have lots of cheaper mechanical parts but that doesn't mean they won't last a long time if used gently. High end microscopes are still built to last a long time even if they don't weigh as much as they used to.

What really matters is the build quality of the optics. Optics have gotten a lot better. Coatings, in particular, work better and last longer. Modern high-quality objectives are large and heavy and over-engineered when compared with older equivalents. The parts of a microscope that matter are better now than they ever have been before. A gear is just a gear. It can be replaced with something someone 3D prints or machines. But an objective is a long-lasting critical element of the performance of the machine.

We have access to a lot of cheap microscopes, not built to last nor built with great optics. They will not be remembered 50 years from now, though, just as cheap microscopes from 50 years ago are not really remembered today, inasmuch as they existed.

[microcosmos]

One hallmark of the golden age, I think, is the typography and engraving of specifications on microscope parts in beautiful technical lettering typefaces instead of simply printing them digitally in arial/helvetica. It doesn't appear to affect the optics or mechanics but it could reflect the quality of the effort and processes that went into making other, more critical, parts of the instrument. More broadly it reflects the culture that went into the design and engineering of microscopes that is different from today.

Some examples from the golden age:

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Even the field diaphragm markings were engraved on the Olympus BH2 series:

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This is what things look like today. I've seen objectives that have had their printed text partially rubbed off with heavy use.

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[Scarodactyl]

Ah, but the up side to that is the chance of spotting delabelled high end optics for great prices. Just have to remorize what the barrels look like.

[apochronaut]

Early painted barrels easily wore off but that situation has been improved upon with more permanent markings. Of as much importance is attached to the plating. Modern barrels are enamelled., anodized, plated with chrome or in finer examples ceramic coated but just as with the loss of engraving from about 1985 onwards, the loss of older protective plating or raw stock also ensued.

Early barrels and most today were brass, and then plated or lacquered. Some barrels were just machined and untouched. The barrels usually only had to be in contact with the oil or salinity from fingers but labs were not always as clean! filtered and ventilated as they are today. Recognition of potentially foul ambient conditions and or contact with reagents dictated some quite variable choices for plating materials.
Picture 1) shows a group of pre- W.W.I objectives built in a fairly standard fashion : 3 lacquered brass barrels with a front lens bezel plated with nickel, a non-tarnishable metal plating and in one case a copper barrel and a solid non-tarnishable front housing.
Left to right. 1) Spencer pre w.w. I lacquered brass homogeneous immersion objective with probably a nickel plated front housing. 2) Turn of the century Spencer homogeneous immersion objective of similar construction. 3) Bausch & Lomb pre-w.w. I lacquered brass objective of similar construction. 4) A circa 1880 Bausch & Lomb First Class objective 1/12" 1.40 N.A. with correction collar. This is one of the first B & L correction collar objectives built right around the time of the 1878 patent issued to their employee Robert Tolles. Interestingly, the front bezel is plated with a non-tarnishing material, very silvery and shiney. Possibly Rhodium? 5) A very old copper bodied objective with a solid shiney silver front lens housing. Rhodium, although rare had little commercial value in the 19th century.
The next group of 5 are the same objectives but the order is reversed. From the left.)
1 ) Bright silver tipped 15X objective with a copper barrel
2) Bausch & Lomb circa 1880 1/12" 1.40 First Class ( likely apochromatic) lacquered brass with correction collar.
3) Bausch & Lomb 60X .85 lacquered brass with a tarnishable tip
4) Spencer 1/12" 1.30 lacquered brass with a tarnishable tip
5) Spencer 1.8mm 1.30 lacquered brass with a tarnishable tip.

[microcosmos]

Have you considered writing a book/article on the evolution of objective housing materials and manufacturing methods, or has it been written somewhere already? I think it will be very fascinating.

[apochronaut]

A representative collection of circa W.W. I high power objectives, all of which appear to have a nickel plated tip. At least the plating seems to tarnish in a fashion similar to the way nickel does.
From left to right.
1) Bausch & Lomb.
2) Voigtlander
3) Bausch & Lomb
4) Zeiss
5) Schutz- Kassel

[apochronaut]

It seems that for certain applications lacquered brass was not used. Both Spencer and Bausch & Lomb offered objectives in a bright silver plate prior to W.W. I. Whether these are chrome or not is open I guess. As previously mentioned, some of the rarer transition metals, rhodium and iridium had few uses in the periods these objectives were made in but their inertness was known. Chromium was also little used at the time. The Bausch & Lomb objective in particular does not look like chrome to me. It is of a bluer reflectance.
The picture shows a pre-war lacquered brass Bausch & Lomb and Spencer objectives flanking similar construction pre- W.W.I B & L and Spencer objectives finished in a high lustre silver coloured plating..

[apochronaut]

Both Bausch & Lomb and Spencer used a kind of colour code for their objectives that were made to higher levels of colour correction. They both kept this code ( somewhat altered in the case of AO/Spencer) until the end.
After B & L transitioned from brass coloured objectives to chrome objectives they maintained the brass colouration for apochromats and brass upper/chrome lower colour for fluorite.
Until the first W.W. was over Spencer used brass for apochromats nut afterwards, brass ( and later chrome) was the choice for achromats, black upper/chrome lower for fluorite and gold plating for apochromats until 1955. Later apochromats had some gold colouration on them as a code.

The question of why gold?--- comes up. It is inert. Other inert alloys are commonly used for the front lens housing, iridium comes to mind , since microscope objectives are sometimes exposed to reagents or somewhat corrosive samples.
Top to bottom.
Bausch & Lomb 1920's 60X .85 fluorite and 1980's 80X .90 flat field fluorite
Spencer 95X 1.30 fluorite and 4 mm .85 and 43 X .85 L.W.D S.F. fluorite type objectives. 1920's to 1950's
Bausch & Lomb First Class 1/12 1.4 , apochromat 90X 1.30 w./ iris and Flat Field apochromat 75X 1.20 .1880, 1950, 1975
Spencer brass apochromat 10X .30 circa 1910, gold apochromat 44X .95 w./ correction collar 1955, early 60's infinity corrected apo 43X .80 w./ correction collar and 40X .80 plan apo from the 80's
A family portarait of Bausch & Lomb objectves from an 1880 First Class to a 1980 planachro with iris diaphragm.. Note that B & L went from quite long, roughly 45mm objectives to the well known 36.65mm short objective by the turn of the century and for 60 years, then back to a roughly 45mm length subsequently in the flat field and plan era. Bausch & Lomb 160mm systems made after the discontinuance of the Dynoptic/Dynazoom 160mm scopes were imported designs by Olympus, Kyowa and then out of China, sold as lower cost entry level or second tier systems.

[apochronaut]

A family resemblence? Who made the 100X W objective?

[Gatorengineer64]

How do the golden oldies perform compared to modern? If you scored modern 100 the old ones are?

[apochronaut]

Have you considered writing a book/article on the evolution of objective housing materials and manufacturing methods, or has it been written somewhere already? I think it will be very fascinating.

I have seen some smatterings of writings. It would be difficult to assemble enough material to do a thorough analysis. It would take years and years with a lot of major gaps in information still.
The little skinny black objective pictured above for instance. My impression of it as a fluorite type is speculation. It is 4mm and has an N.A. of .85. The performance is outstanding .; very good resolution and exceptional colour correction. It performs like a fluorite or better, yet nothing is written on the barrel. Just the tube length : 160mm. I have seen quite a few of them, around 10 or so and they all perform really well but there appear to be two types. Some have a normal 4mm cover slip correctrd working distance of about .5mm but others seem like they may be no cover . The barrels don't say. I have never seen any reference to them and there must have been something in their application that required the barrels to be so thin? They are made of brass tubing.

.

[apochronaut]

How do the golden oldies perform compared to modern? If you scored modern 100 the old ones are?

They are all different but in general I would say that by 1900 most of them performed to their type. That copper objective with the rhodium front cell is fairly primitive . The 1880 1/12 B & L , pretty good but not as resolved as the Spencer 1/12 from 1905.
Most I have used, if you attend to the adjustment of the condenser critically , will give an image with resolution as good as modern objectives of similar N.A., only lacking some contrast. Some, have remarkable contrast. Most do have a noticeable lack of planarity but with the eyepieces intended for them, this is corrected for somewhat. The fields of view are seldom over 13mm so that is a distinct difference. They do respond in some cases to certain modern wider field eyepieces to give an almost contemporary grade image. All of the apochromats, even those from 1905 are excellent but there has been a continuity of development with apos that has allowed the fields to broaden a lot. Apochromats up untí 1955 or so could only be expected to produce a fully corrected field of only about 13mm maximum. The Spencer gold plated 10X .30, 20X .65, 44X .95 and 90X 1.4 is a superb apochromat set which I have found some more modern compatible well corrected 18mm f.o.v. compens eyepieces for.


The brass plated B & L 75X 1.2 N.A. oil flat field apochromat and the AO 40X .80 planapo are only about 35 years old, so they produce contemporary wide field imaging consistent in quality with any modern plan apo.

To put their performance into perspective as a group is difficult but they pretty much all perform to specification. One difference between most of the microscopes they are from and a contemporary off the shelf mass marketed scope is that the operator of a vintage stand needs to be more highly skilled at condenser adjustment. Modern led fitted scopes don't respond so badly to condenser maladjustment, so amateurs might not need to be good microscope technicians in order to enjoy their hobby.
When it comes to the older fluorite and apochromat systems, you would have to pay handily in order to equal their performance with a contemporary scope. An off the shelf $1000.00 oriental scope, just isn't going to cut it. Apochromats are apochromats. Condenser and illuminator adjustment were regarded seriously with those older instruments and can make the difference between so so imaging and stellar imaging. The Spencer # 5 was even fitted with a 1.4 N.A. achromat condenser carrying a circular iris and oblique iris with the entire mechanism regulated by a coarse AND fine condenser focusing system. That was the stand those gold plated Spencer spochromats were made for.
Many older quality stands had multitudes of stage options , from simple clips to very precise and intricate circular revolving models. Having a fine stage, sets these older gems on another plane, something average modern microscopes cannot easily attain without a massive cash outlay.

I use older stands occasionally. A Spencer 5 built after 1937 with 4 apochromats sometimes or a 1925 # 7 with 2 apochromats and a fluorite. The 7 was borne out of the Spanish flu pandemic, one of the first dedicated binocular research microscopes. It has an upright tube and can be optionally shifted over to a monocular mode. The # 5 originally was a monocular research stand from 1915 right through the middle of the pandemic, using similar optics. Most stands were monocular then. It seems that the rationale for binocular viewing came to the fore during that period. The # 5 went away for a while, eclipsed by the # 7 , then was reborn in the early 30's as a low fine focus heavy binocular research stand. 15X eyepieces are default on it due to their wider apparent field and the high working N.A's of the objectives. Magnifications up to 1350X in increments of 50X, 100X, 150X, 200X, 300X, 400X, 440X, 600X, 660X, 900X and 1350X are possible without entering into empty magnification. I recently discovered so me modern 18mm compens eyepieces that work perfectly. The stand can also be fitted with any other 34mm parfocal Spencer objective, if lower magnification or greater w.d. is required.
The whole system including a 100 watt illuminator for high resolution DF ( there is a funnel stop for the 90X objective) was about 500.00, picked up in bits and pieces.

[microcosmos]

The little skinny black objective pictured above for instance. My impression of it as a fluorite type is speculation. It is 4mm and has an N.A. of .85. The performance is outstanding .; very good resolution and exceptional colour correction. It performs like a fluorite or better, yet nothing is written on the barrel. Just the tube length : 160mm. I have seen quite a few of them, around 10 or so and they all perform really well but there appear to be two types. Some have a normal 4mm cover slip correctrd working distance of about .5mm but others seem like they may be no cover . The barrels don't say. I have never seen any reference to them and there must have been something in their application that required the barrels to be so thin? They are made of brass tubing.

Have you tried this black objective with crossed polars to see how strain-free it is? If I understand correctly there was a convention for pol objectives to have black barrels, although I don't know when this convention arose.

I tend to like the look of fat objectives but this thin black one looks very nice and stands out.

[apochronaut]

I do assume pol for those but Spencer doesn't seem to have that convention, at least after W.W. II. Strain free optics were designated with some form of red indicator, usually a red mark or red lettering. Objectives were given an SF designation, later an S suffix where the cat. # was stamped. There were some older black Spencer objectives though, looking just like black versions of regular objectives.
I do have an entire set of Bausch & Lomb black objectives from the 50's, again looking just like the chrome ones, each with a red dot on them.

[apochronaut]

I edited my answer a bit above gator.
Here are some links from some older posts about the Spencer stuff.

viewtopic.php?t=2689
viewtopic.php?t=1042

[BramHuntingNematodes]

I had thought that B&L made black objectives for their projector microscopes for whatever reason.

[apochronaut]

That might make sense since the cheaper to apply enamel might not be as durable but not needed to be on a projection microscope. Also there would be less reflection in a darkened room. The group I have all look like standard B & L objectives just black with a red dot. 10X .25, 20X .50 and 43X .65. I have a further 97X 1.25 in brushed chrome with a red dot.
What is your understanding of the red dot?

[BramHuntingNematodes]

I only have Zeiss strain free optics, but in B&L I have a red dot on my 12.5x compens eyepieces and 215 TL metallurgical fluorite 4mm eq. focus objective.

[apochronaut]

I thought that S.F. on a lot of those old Zeiss objectives stood for StrainFull .

[BramHuntingNematodes]

The most wack lens I have is actually on a Wild condenser. Looking through it with crossed polarizers reveals two very dark waves. It's completely unusable for pol.

[AntoniScott]

The answer to this very interesting question is dependent on when the individual became interested in microscopy. For sure, the mid to late 1950's saw a huge influx of "entry level" microscopes to fill a huge void and demand for an inexpensive alternative to what was currently available at the time. It was inconceivable at that time that any reputable microscpe manufacturer would produce a sub-standard instrument with their name on it. It opened up an immense market for an inexpensive alternative.
Names like Spencer, American Optical an Bausch and Lomb in the USA and Leitz, Zeiss and Beck-Kassel in Europe produced outstanding instruments of the finest optical and image quality available at the time. This, however, came with a hefty price tag. Most individuals could never afford such an instrument.

In the mid-1950's Japan entered the market with miroscopes of varying but acceptable quality. Althought these microscopes could not compete with the professional quality microscopes, as far as optical quality, they did offer acceptable optical quality with affordable prices. Japanese microscopes were synonomous with cheap prices and substandard quality. However the hidden secret was that just about everyone could afford one. It probably opened up a huge demand for individuals that wanted something even if it wasn't the best. But it would be a mistake to think that Japan was incapable of manufacturing top end high quality microscopes.

Dozens of inexpensive brands were available everywhere during the mid to late 1950's, and all from Japan. First and foremost to capitalize on this market came from many USA catalog companies and chain stores like Lafayette Radio and Electronics that offered a staggering variety of microscopes from inexpensive to outright expensive.

I can't imagine the impact on people at the time, but I did think that these inexpensive microscopes and the myriad accessories associated with them, made a huge imapact on interesting people to furthr their interest in science and associated areas of study.

Antoni Scott