Should I avoid vintage Leitz Scopes?

[Joe Henry]

Correct me if I am wrong but Leitz scopes from the 50's - 60's (the old black enamel) use odd ball objectives of 170MM, which I assume means other companies from the same era objectives will not interchange and/or will result in poor imaging? Is this a reason to avoid these scopes? Thanks and Merry Christmas!

[Scarodactyl]

No brands from the finite era are fully interchangeable. Unless you're doing something weird or specific you ahouldn't have too much trouble filling a nosepiece with objectives that are the correct type or probably close enough.

[PeteM]

This article includes information on which 170mm and 160mm Leitz objectives can interchange.

http://www.microscopy-uk.org.uk/mag/img ... es7rev.pdf

There's a general plus and a general minus for Leitz finite scopes, IMO. The plus is that most are beautifully made (arguably mechanically better than Zeiss, Nikon, and Olympus scopes that competed head-to-head in times past) and with good optics. Compared to Zeiss, you'll find far fewer delaminated optics and a somewhat more direct mechanical design. In some cases, you can buy older Leitz plan apo and other desirable objectives quite affordably.

The minus is that figuring out what parts go with which generation of Leitz microscopes gets complicated - and even more complicated when some sellers label Leitz parts as Leica and sometimes vice versa. Same company, but different eras and managements.

Leitz-Leica ad at least four different head sizes for various generations, four different condenser mounts, and so on - spanning finite to infinite models. There were short barrel and long barrel 170mm objectives, Plezy adapters for backward compatibility, DIN standard 160mm objectives with some backward compatibility (as in the article above), and then four different infinite systems. The present company is owned by Danaher and has bits of history from Wild Heerbrugge in Switzerland, American Optical, Reichert, and several others. All of which is to say, there's a learning curve in sorting out what goes with what.

Once you sort that out, you can have an excellent-performing classic black microscope that will be a pleasure to use. More recent series with off-white frames may have slightly wider fields of view and perhaps better lens coatings and contrast. Even more recent infinity "DM" series microscopes offer superb optics but at a price.

[Alexander]

Correct me if I am wrong but Leitz scopes from the 50's - 60's (the old black enamel) use odd ball objectives of 170MM, which I assume means other companies from the same era objectives will not interchange and/or will result in poor imaging? Is this a reason to avoid these scopes? Thanks and Merry Christmas!

Microscope objectives from different brand are not interchangeable in general. Finite ones need matching correction eye-pieces and infinite ones need matching correction tube lenses. You never get the best quality by mixing brands.

[Scarodactyl]

Microscope objectives from different brand are not interchangeable in general. Finite ones need matching correction eye-pieces and infinite ones need matching correction tube lenses. You never get the best quality by mixing brands.

Only some brands of infinity corrected lenses need matching tube lenses. Some brands can be mixed without any loss in optical quality, though the logistics can get complicated with different parfocal lengths.

[Alexander]

Some brands can be mixed without any loss in optical quality,

What brands beside of Nikon are on the list?

[PeteM]

Some brands can be mixed without any loss in optical quality,

What brands beside of Nikon are on the list?

The loss of optical quality is a matter of degree in my experience. While Nikon aims to do all of its corrections in the objective, the latest Olympus UIS and Leica HC objectives don't seem to rely heavily on their tube lenses for corrections. Once fit with parfocal extenders and thread adapters, they can look good on a "neutral" Eclipse tube lens. Leica will keep its stated magnifications (both Nikon and Leica have a reference tube length of 200mm), and Olympus will be off by a 200/180 factor but still with decent images even as seen through a camera. Since the only infinite 1.5x and 40x water dipping objectives I have are Olympus UIS, I'll sometimes use them on a Nikon Eclipse. I've also tried a Leica 20x Plan Apo with a .65 an shimmed out another 15mm on a Nikon. It was good, but not as good as the spectacular (and spectacularly cheap) Nikon 20x Plan Apo .75na.

I've also tried a variety of RMS thread infinity objectives on Leica DM systems after adapting the threads and making things parfocal. Most look very good to the eye and many still look good to a camera, with only the slightest color fringing at the edges of the field.

I don't imagine nearly as good compatibility with Zeiss since it has the shorter 160mm reference tube length and apparently still does significant corrections in the tube lens and eyepieces. I haven't tried it, though. Zeiss' infinity stuff is expensive and as far as I can tell they picked the wrong reference tube length (from an optical standpoint), perhaps to keep their microscopes compact. Someone here may know more about the pros and cons of Zeiss infinity. I do know researchers who love their inverted scopes with multiple imaging methods.

The Chinese are also now making new infinity clones, mostly of Olympus and sometimes Nikon infinity objectives. I've been slightly disappointed in the ones I've tried, though they were somewhat older Motic, AccuScope, and AmScope branded. Decent images, but just a bit behind in image quality comparing plan achromats to plan achromats and plan fluorites to plan fluorites. Could be they've since narrowed the gap - with no loss of image quality for the clones.

[Scarodactyl]

What brands beside of Nikon are on the list?

Olympus (the slight 180 vs 200mm difference isn't a big deal), Mitutoyo and the fleet of clones and knockoffs made by other companies, plus specialty objectives like those by Thorlabs or Optem. I have used all of these options on my Nikon scope at one point or another. Optically they play together beautifully--if there's any incompatibility in corrections there it's too subtle to affect photography. This isn't too surprising since Olympus and Nikon both claim their objectives are internally corrected.
This is however on a metallurgical microscope with a very large range of travel, so accomodating 45 and 95mm parfocal objectives isn't a problem. On a biological microscope parfocal length is a major obstacle. But for me it has been a real benefit for my photography to be able to mix and match.

[Alexander]

I buy everything you said with the exception of:

I don't imagine nearly as good compatibility with Zeiss since it has the shorter 160mm reference tube length and apparently still does significant corrections in the tube lens and eyepieces.

Zeiss infinity systems do not have correcting eye-pieces. They are perfectly neutral above the tube lens. I own a Zeiss infinity scope.

About the tube length: Zeiss is still the world market leader with Nikon and Olympus 4th and 5th. Looks like Zeiss does at least something right.

[PeteM]

. .

Zeiss infinity systems do not have correcting eye-pieces. They are perfectly neutral above the tube lens. I own a Zeiss infinity scope.

About the tube length: Zeiss is still the world market leader with Nikon and Olympus 4th and 5th. Looks like Zeiss does at least something right.

Thanks, Alexander. The earlier comment was based on this Olympus quote, which I mistakenly extended to eyepieces: "Still other manufacturers (notably, Zeiss ICS systems) utilize a combination of corrections in both the tube lens and objectives."

https://www.olympus-lifescience.com/en/ ... nityintro/

Any idea of how extensive the Zeiss tube lens compensations are?

[Alexander]

. .

Any idea of how extensive the Zeiss tube lens compensations are?

Sorry, I have no idea. I can only discuss what is fact above the tube lens.

[apochronaut]

If you think about the eras when AO( read Reichert and Leica) and Zeiss West embarked on the infinity corrected adventure, there are complex reasons for their choices. All of that took place between about 1960 and 1980+ and when shifting to such a high gear, it was easy to lose your traditional customer base, so allowing for an equipment continuum was very important, especially in the earlier part of that time frame.
AO felt no need to change from 34m parfocal in 1960 because it wasn't until about 1980 that the barrels became too short for them to stuff everything in there to get high end advanced planachromat performance with infinity correction and in doing so , they allowed for existing 160mm 34mm objectives to be used in the infinity system. They work well enough with the caveat that they provide about 20% greater magnification and their older optical design and coatings make generally for poorer overall performance, obviously. Why did AO then settle on 182.5mm for a reference focal length? Well it turns out that they had been playing around with tube lenses for years. The AO series 4 has an apochromatic tube lens that lengthens the tube to somewhere around 180mm. It was a win win win situation . The luddites could use their older objectives in a series 10 and those that wanted to move into the future with an entirely new system and concept could as well. In the late 60's and through the 70's Reichert and their AO parent continued with parallel 182.5mm infinity systems, each jumping to 45mm parfocal objectives when further plan fluorite or planapochromat corrections required more glass in the barrel.

Zeiss, West, started into infinity correction with an entirely new concept, obviously not intending continuity between the past and future. The Axiomat of 1973-1985 was huge with dedicated , montrous objectives and targeted towards research only, all while continuing until the late 80's with R.M.S 160mm microscopes. When they did introduce more compact consumer friendly infinity corrected scopes, they abandoned the rather lengthy 250mm reference focal length of the Axiomat behemoth and settled on 164.5mm. Why 164.5mm? Why 182.5 for AO and Reichert?
Firstly, the optimum reference focal length for an infinity microscope is related to the tube diameter. The larger the tube diameter, the longer the feasable focal length. This is why both Zeiss West and Zeiss East could get away with longer focal lengths for their giant research stands because the microscopes are huge. Brought down to size, a more compact R.M.S. microscope's optimum length is about 180mm, certainly no longer than 200mm. It isn't by accident that Leica quickly evolved the AO/Reichert system that they inherited out to 200mm, along with a larger overall dimensional cross section of their microscopes. Thrre are some potential advantages. The same is true for Nikon, allowing for more features for the professional but again back to a larger ovrrall microscope. Only Olympus held the line at 180mm. with R.M.S. optics and then Zeiss at 164.5mm and R.M.S. optics. But why 164.5 and not 160 ?
I think it has to do with the method of measurement. You can measure from the surface of a lens to the focal point or include the refractive space in the lens from the transverse lens center. With AO, that measurement is 2.5mm. I am guessing that with Zeiss it is a little thicker. Remember that in the 160mm system, the back focal plane or transverse lens center was not part of that 160mm, and in fact when the space between there and the objective shoulder is included, each objective has a unique focal length but there was a general agreement on reference points with which to determine the 160mm tube length and manufacturers designed their optics accordingly . Does this exist with infinity reference focal lengths?
I am guessing that Nikon and Olympus measure from the lens surface and using that criteria , Zeiss West is actually 160mm. Does anyone know for sure?

Or for that matter, similarly to AO, did Zeiss 160mm objectives work passably in the infinity system, to give the luddites a break and allow a slow transition to infinity, if a customer was overly attached to an objective.

[PeteM]

Phil, I don't know how Zeiss measures infinity tube length, but numerous sources list their reference tube length as 160mm.

There are also discussions suggesting that a longer tube length is capable of better performance: ". . . Tube lengths between 200 and 250 millimeters are considered optimal, because longer focal lengths will produce a smaller off-axis angle for diagonal light rays, reducing system artifacts. Longer tube lengths also increase the flexibility of the system with regard to the design of accessory components."

https://micro.magnet.fsu.edu/primer/ana ... intro.html

[apochronaut]

Yes, the longer tube is optimal but only in the context of a broader optical pathway. Who used(es) a long tube on a more compact microscope? Maybe the East Germans. I don't know their product line well.
I think the 160mm is just people rounding off. Authoritative sources, those with in depth knowledge of the patents nail it at 164.5.. You would be disputing that with the wisdom of Herbert Gross and Yueqian Zhang, not me : way out of your league.

[PeteM]

It might well be that 160 mm reference tube length is a rounding error or, as you suggest, that there are different ways of measuring it. I've also seen 165 mm as a claimed spec.

I don't know - you might - if Zhang actually measured reference tube lengths, asked Zeiss, or pulled them from the patents. His lens index has them all at 164.5mm. In contrast, the FSU link by Prof. Davidson puts it at 160mm. Maybe he just asked Zeiss? In any case, Zeiss's own "campus magnet" website repeats that reference lengths from the major makers range from 160 to 200mm. Davidson might well be careless or wrong. He might also be right. Zeiss might have patented one thing and decided to build, measure, or advertise it in a slightly different way. "164.5" doesn't sound all that snappy.

In any case, the up-to-5 mm difference doesn't matter in any practical sense I'm aware of. The 25-40mm difference to the Leica and Nikon 200 mm standard, along with their wider optics, might. Leica and Nikon make that case.

For what it's worth, the newer Zeiss "Primo" line uses the Olympus 180mm reference tube length - a departure from Zeiss's other scopes. This is probably because that is what Motic builds and can label as Zeiss rather than being based on optical considerations.

[apochronaut]

Professor Davidson also states this " the German microscope manufacturer Reichert originally pioneered the concept of infinity optics. The company started experimenting with infinity-corrected optical systems as early as the 1930s followed later by Leica and Zeiss, but these optics did not become standard equipment with most manufacturers until the 1980s "

That partial paragraph has so many ludicrous falsehoods in it that I hesitate to repeat it because a whole bunch of amateur microscopists will still blindly believe it because it came from what is positioned as an authoritative source. It must be the gospel. There are also a whole bunch of people out there who don't know enough to know what they don't know. That's how the gospel gets spread.
I pointed the falsehoods out to Michael Davidson and received an acknowledgement of them many years ago but nothing was ever changed in the text.


Of course Zeiss uses an off the shelf wonky system for their entry level China made offering. It is essentially Motic, can be found as other brands with minor cosmetic changes and is more Olympus than Zeiss. That's the plan. Nikon uses a China made stand with 45mm parfocal R.M.S. objectives instead of 60mm parfocal M25 on theirs. Bausch & Lomb used a China made 160mm finite stand for theirs instead of the modified infinity system. The China made CX 31 is not upgradeable within the Olympus system. In many cases manufacturers purchase inexpensive entry level off the shelf products that do not complement their product line nor can be complemented by it. This serves a number of purposes but mostly It keeps the brand in schools and puts the brand in the hands of new users, which hopefully translates into brand loyalty. However, that loyalty is expected to be realized in the purchase of a new system ready microscope, not an upgrade to the existing stencil brand. It's the microscope company version of upselling.