ZEISS OPTON W – Let’s make things better

Working a lifetime (I’m 67 now) with microscopes of different brands and types I have learned the strong and weak points of many microscopes. Every microscope has weak points, even those instruments you can trade for a new sports-car. Generally spoken the worst instruments are those which are designed by the marketing department of the firm, being Wetzlar, Jena or Tokyo based. Now I have come to an instrument which comes near to perfect, was to expensive for the market and for that reason was brought in its early youth to the churchyard.

I have fallen in love with the Zeiss Opton Stativ W.

 

The W is one of the first postwar instruments, and designed from scrap by refugees.  In 1945 about sixty Zeiss people fled from Jena to Oberkochen in the free world because they did not want to be send to Russia or elsewhere in the communistic world to develop ‘communistic’ instruments. They were not that welcome in the Zeiss family and after difficult negotiations they started there own  factory, the Opton Optische Werke Oberkochen. Zeiss owned 95% of the company of brave technicians. While Kurt Mitchel was developing his Zeiss L and Standard they went other ways. The result was an uncompromised instrument, made from the best materials, of highest precision and with some very unknown features. For instance you would not find a substage on this stand. The condensers fit with a clever designed bayonet in the subtable. On the condensor a level permits lifting the condenser for 0,8 millimeter. This only for correcting for the thickness of the glass of the slide. The bayonet centers the condenser and I was able to get a sharp projected image of the field diaphragm in all specimens. Mind you: sixty years after the W left the factory!

The substage stageholder blocks the stage in use with one knob. So changing is easy, tolerances are zero.

Fit of the round sliding stage.

Sliding stage with its immersion plate. It works great if you use the right grease to slow down its movements.

The square stage turns around 270 degrees. Again a charm, for you can navigate through your specimen by turning table and knob. This picture has been made to show you a real Carl Zeiss logos.

The Opton designers (this article is a tribute to them) followed the sound L-armdesign of the prewar Zeiss L-stands and changed, like Kurt Mitchel, to one axis focusing on the table. There ends the analogy with the Zeiss Standard and the L and for good reason for the indecent love in those Mitchel-instruments for round curves has a lot of drawbacks in terms of stability and making room for accessories.

 The Opton is not blessed with a great range of accessoires. You have to do it with a fixed revolver for four objectives, interchangeable condensers (darkfield to), an enlargement changer with a Bertrand lens for phase plates alignment and some accessory camera equipment, a filterslot on the illuminator. It is clear: the genial designers wanted a microscope for brightfield and phase contrast and if you want epi, fluorescence or differential interference contrast go to our StepMother.

 Universal condensor 1.30 with three phase plates and slider for oblique illumination.

  Brightfield condensor 0.90.

Precision

If this is a sound idea for the small factory had no means to build more or because a limited arsenal of build-on things leads to more precision in the basic instrument I don’t know. I tend to think simplicity works. Fact is that this microscope is of the highest precision I ever saw and for instance the drawbacks in precision and ease of use in the Leitz Ortholux and Orthoplan are to trace back to the box of building blocks it is.

And the W shows tolerances zero. I had two on my desk (they say only five sold in the Netherlands) and was flubbergasted noticing that on the one a given point in a specimen was after copying the vernierscales on the other exactly X. Hold your breath.

  Binocular tube of unusual design.

Mat hatter

First thing you notice is the most unusual design of the binocular tube. This ‘top hat’,  as the thing was quickly nicknamed, maintains under all circumstances the mechanical 160 mm tubelength. The design of this tube seems to exclude a photoport, but for making pictures they provided a beamsplitter with a laterally offset tube. There is also a straight monotube to mount a camera. A third tube on the top hat would have asked for a most complicated design of sliding prisms and swing out/in relaylenses, etc. So I think the designers did not even think about building it. Besides that Zeiss West produced already a great focusing telescope system on which could be mounted different types of camera’s. That one could be mounted on the supplied Orton monotube, so why introduce a thing that brings in risks for the imagequality. And certainly should not be bought by anybody. I had not a chance to test the beamsplitter.

The binocular tube has a remarkeble feature I discovered lately. On turning the right pipe for adjusting your personal pupil-to-pupil distance both pipes are out of their horizontal line. To correct this one can turn the whole upperplate of the binocular tube. Doing this I discovered another thing and that was that both my eyes are not in an exact horizontal line.  Conquering the deviation with the tube I believe this services tireless observation. Great for the analyst who had to observe hundreds of say bloodsmears on a day and great for me sitting besides my pond and observing for long periods all little things.

Yes, I intend to equip the illuminator with a led and are breeding on ways to do it without modifying the bulbholder.

   

The illuminator can slide on its foot which is a great way to center the filament.  This slider is metal but in the first instruments made of glass. The bulb is factory precentered.

Köhler is watching you

A sign with glowing capitals HERR DOKTOR KÖHLER IS WATCHING YOU was erected in the atelier I suppose for I never encountered a microscope on which with a light touch of the finger you can achieve total Köhlerlight. That thanks to the precentered 6V bulb, swing in groundglass positioned between collector and bulb (no noise in the image), precentered condensers (only a hammer will decenter them), and a most sophisticated illuminator. Well, it is covered with real leather, but that is not what I mean. The mirror in it is surface coated, no double filament projections.

On the phase condensor are two centering screws for each phase plate. In the original design the pair of centering screws were of different ‘feel’. On ‘my’ condensor they are the same, presumably because this instrument is one of the latest. On both condensers the diaphragms has no lever but a small hoop which is difficult to fiddle. In the big condensor you can obtain oblique illumination. Great.

  

The Plan 40x is fitted with a lock which makes (for safety reasons) the objective shorter. Not in the picture and never seen a dry achromatic objective 63x/0.9 with correctioncollar. (Seen it from Zeiss West and it is a most usefull objective for those who hate fiddling with immersion oil.)

This stand deserves the best optics and they are. The plan achromats 2,5x and 40x are even plan combined with widefield eyepieces. The phase 40x and 100x objectives bring the most undisturbed, clean phase images I ever saw, of course in combination with the supplied monochrome filter. I think those objectives surpass Leitz phase achromats of the same epoch. All objectives are of the highest correction and you don’t feel the need for fluorites. In other words, if you don’t intend to make colour pictures those are the things to use. Of course no comments on sharpness, and vivid bright images with not a trace of analogue artefacts.

The table is marked Carl Zeiss as is the binocular tube. That makes me believe this instrument is one of the latest marketed. In 1948 Opton went fully to Zeiss and production of the W gradually finished.  Zeiss West could not claim ‘we make the two best microscopesystems in the world’, but murder in the first degree of the W is a shame for everybody who wants the best. And the W is the best. Working with it is a delight and a honour. The W is the prima ballerina on my desk.

LED

Of course because there are no spare bulbs to find I like to build in a led. Because the W is promoted working horse I feel I  have the right to do that. And it will not be that difficult to replace the bulbholder, saving the original piece of bad plastic. And by the way no more plastic to find in this instrument.

Factory numbers

For those who will be able to tell more of this instrument I give the factorynumbers of the different parts: Carl Zeiss stage 204533, Carl Zeiss tube 201533. Everything else is Zeiss Opton: Plan 2,5x 183011, Plan 40x 226327, achromat 10x 118911, phase 40x  226327, phase 100x 210355, condensor 0.9 218552, universal condensor 1.25 207240. The stand self bears no number and rests on three little cork rounds. A small detail which tells of the love for their trade of the designers.

Acknowledgment

Thanks to Mike Samworth of Britain, Secretary of the Postal Microscope Society who draw my attention to some literature about the ‘Arbeits- und Forschungs-Mikroskop Stativ W’.