Leitz eyepiece question

[wporter]

I have a Leitz 23mm eyepiece marked "Periplan, OK. 8xB" , and was wondering what the OK and the B signified.

I have previously learned that an "o" (in the catalogs printed as a superscript) means a slightly larger field diaphragm (to prevent vignetting in photo use), and that "M" means a focusable eyelens. I've seen "Proj" on some ebay eyepieces, on the lens just before an OK, signifying use as a projection lens. But the B and the OK aren't called out in any of the Leitz literature I have.

[MicroBob]

OK means "Optisch Kompensiert" = CVD correction for stronger achromats or apos
B means "Binocular" = One of a pair of specially hand selected eyepieces that work together especially well in a binocular tube.
The magnification and field aperture were fitted especially well together in these pairs.
Probably from the 1950s.
Later all eyepieces were deemed acceptable for bino use. Probably a combination of increased manufacturing precision and reduced expectations.
I guess that many eyepiece pairs today wouldn't pass the old Leitz test.

[wporter]

Great information, MicroBob, thanks a heap! Good to have some knowledgeable Leitz people on the forum.

I guess you're right about the era; none of my literature resources pre-date the late 60's, and they don't mention OK & B.

[apochronaut]

Different glass batches in the old days would have slightly different properties, so in building a design the mfg's would have to do some mechanical adjustments in order to meet spec.This is why two identical objectives often have different shimming and slightly different parfocality.
With eyepieces, I suspect that rather than make physical alterations to the eyepiece, they probably selected pairs that performed equally from a given mfg. lot. Many of course went for monocular use.
For pairs, as close to identical focus would be ideal but not absolutely necessary, due to the diopter but magnification factor would need to be pretty close and the diameter of the field stop would need to be perfect. Some of them can be moved.
Glass has become more consistent as time has marched on and mechanical mfg. more precise.

[ebenbildmicroscopy]

This is a wonderful post...

it speaks to a sortuv homespun almost "craft industry" notion of manufacturing that few people have an understanding of today. The Leitz plant in Wetzlar, back during this era, employed about 500 workers. Of all the "manufactured" things I collect, Leitz microscopes demonstrate the greatest diversity in form. I'll do a post soon that illustrates this but, just off the top of my head, I can think of about 6 or 7 different microscope components that, when compared over the span of these same ten years, vary enough that, having the same function, I've always blamed the differences on either a machinist or engineer who wanted to vary the form for the sake of appearance, or being able to offer the highest quality, or both.

I'm not suggesting these differences don't exist in manufacturing today, but I would tend to attribute modern changes to be more influenced by economy rather than aesthetics or standards.

[MicroBob]

In this era monocular microscopes were the norm and binocular was new and had it's advantages but also disadvantages (more glass in the optical train, weak or no coatings). I can imagine that there were critics that closely looked at new binocular instruments to proove the superiority of the monocular instrument. For the manufacturer binocular was more attractive because some competitors didn't have it available and becaue the instruments were more expensive. So they might have taken care to ship only perfect instruments. I have no proof for this theory but it sounds likely.

[ebenbildmicroscopy]

YES! And, we almost take styrofoam packing and form-fitted packaging for granted these days. I was trained by a machinist who went through the German 4 yr apprentice program for master machinist and trained in the shadow of the Leitz plant back in the late 1950s. I asked him one day (while packing up some custom optical components we had made "special order"), "How did they ship microscopes back when you were an apprentice?" He almost had to look to the sky and contemplate before answering, "EVERYTHING was shipped in 'excelsior'... and it left dust and shavings everywhere and it got fairly matted down by the time it arrived here from Germany on a ship!"

[apochronaut]

I have a German hobby microscope from the 30's. No mfg., just a magnification table on the door marked above, microscope # 1266, with the 2 rewritten in pencil as a 3, so I guess it is microscope # 1366. It is society size and has one of those stacking objectives. It is all brass and cast iron and has the finest dovetailed hardwood case you could imagine. When I opened the case, that stuff fell out all over the place, as well as a few pages of the Berliner Morgenpost from Jan.24 1931. The wood shavings had been wrapped in the newspaper sheets and installed in the case as units of packing.

[MicroBob]

As far as I know Leitz, compared to Zeiss was more open for special demands from their customers. So if a company or a professor needed something that was not in the program they were willing to design and build it. For the collector this means that he chooses a lifelong project if he decides to collect Leitz microscopes!
Here is a website that concentrates on Leitz Ortholux boat anchors:
http://www.leitz-ortholux.de/

[apochronaut]

I have a German hobby microscope from the 30's. No mfg., just a magnification table on the door marked above, microscope # 1266, with the 2 rewritten in pencil as a 3, so I guess it is microscope # 1366. It is society size and has one of those stacking objectives. It is all brass and cast iron and has the finest dovetailed hardwood case you could imagine. When I opened the case, that stuff fell out all over the place, as well as a few pages of the Berliner Morgenpost from Jan.24 1931. The wood shavings had been wrapped in the newspaper sheets and installed in the case as units of packing.

A few pictures of the scope. Zero markings and I was wrong. It is not society size. The eyepiece bodies #3 and #5 Huygens type, are brass and the barrels are unplated. The size is strange. 22.7mm, so they will not fit into an R.M.S. tube. The tube length is 170mm.

It does have a unique feature that seems a bit odd for so modest a microscope. It has a stage leveler. If you look at the underside of the right hand side of the stage there is a spring loaded knurled knob for raising and lowering one side of the stage. It is quite tall, at 14 1/2" when focused at low power.
It magnifies 240X and with the extra aux. objective for the deluxe model, 400X.
Wood shaving Berliner Morgenpost wrapped packing. The piece sitting beside the microscope still has the crease in it where it was pressed over the arm and focusers.

[Hobbyst46]

It does have a unique feature that seems a bit odd for so modest a microscope. It has a stage leveler. If you look at the underside of the right hand side of the stage there is a spring loaded knurled knob for raising and lowering one side of the stage.

Is the stage leveler a functionally fine focus mechanism? Since there is only one "ordinary" focusing knob on the scope?

[apochronaut]

It's a pretty coarse thread and it only lifts one side of the stage. The rack and pinion is fairly precise and the microscope only magnifies 400X anyway and that is with the # 5 eyepiece , which is probably around a 15X. Most usage would be below 240X so the coarse focus is adequate. It was probably a naturalist's microscope and the leveling feature a nod to the difficulties encountered while viewing aquatic samples in an uneven environment.

[billbillt]

MAYBE IT COULD BE USED AT A PARTY AS A SHOT GLASS IF IT IS UNUSABLE.. THINGS LIKE THIS ARE ALWAYS A HIT!..

[Sabatini]

Thanks for the nice information, I've expanded the knowledge and on the way it's been a lot of fun.