Finally found a working 47.5 B&L Apo what a fine lens

[BramHuntingNematodes]

I found a 45x which predates the more common 47.5x and it had pretty bad delamination and a crack. A second 47.5x had severe separation in several lens elements. A third 47.5x had a spiderweb of cracks and separated pieces. The fourth had a fine web of mold on the top, but a swab and some canned hexane set that straight and I finally have the full classic B&L Apo set (less the 61x immersion an example of which I have never seen but I do have both the 90xs). I still need a little practice setting the collar right but wow, such nice looks and what great colors! Merry Christmas to Bram!


Fly proboscis


Laguncularia root cross-section (I believe safranin and fast green but not sure, ho, ho, ho!).

I could get rid of the fuzzy edges by cutting maybe 5mm off my camera adapter-- the eyepiece field stop is immediately outside the fuzzy fringe.

I was able to return one of those three bad lenses. It also had a stuck collar so good riddance. It took about eighteen months of looking around, and almost as long to get anything like a decent picture with this scope, but I am pretty pleased with the result. I should be able to document findings better maybe even see some stuff I couldn't before from prepared specimens. I also got the 20x planachromat and 40x flat field phase on the Dynazoom too, with an old Tiyoda turret condensor that fits pretty good so looks like I'm set for looking at worm heads

[apochronaut]

Great find. They used to be fairly common but good ones are becoming scarce. You probably know all this but in case. The 61X exists as a .95 dry objective with a collar and as an oil immersion 1.4, I think it was. There is also an iris diaphragm equipped 90X 1.3 oil for D.F. The iris has a distinctive knurled ring so it looks different than the plain objective. Brass at one time and later black.

[BramHuntingNematodes]

I have a 60x dry achromat, but I didn't know about the apo. Maybe a bit superfluous, and if it takes four of them to find a good one I might not make it before I die! First things first though, I would want to look at getting a proper B&L phase turret and some more planachro phase lenses. The 20x is really great although the 40x flat field is also so nice I might not replace it.

I saw an old Dynoptic with most of the panfocal condenser on it and I'm trying not to think about it too much.

[apochronaut]

Not that easy to find. During the Dynoptic era, B & L didn't offer any advantage over an AO system. A series 4 could offer 26 different phase objective options , more if you included medium working distance and long working distance . The Dynoptic offered 4 options plus l.w.d. By the time the flat field stuff came along, AO still had 9 planachro options . B & L still had only 4 The incentive to buy a Dynoptic phase system wasn't really there, especially since the performance of the flat field objectives was no better than the AO planachros. i don't think they sold very well.
When the planachromats came along, B & L did take a little leap ahead of the AO planachro dark phase system, so the Balplan phase microscope is a bit of a charmer and sold o.k.
Olympus arrived shortly thereafter and posed a new threat. Then Nikon. You might be better off zeroing in on a Balplan phase . Unfortunately, even though the internals are the same, the mount is very different, so the two condensers are not interchangeable. Any flat field or planachromat phase objectives are.

[BramHuntingNematodes]

Thanks, I'll keep the old weather out for the Balplan version too. Although I am really enjoying this old Dynazoom. It's big and sturdy, and the controls feel good. I use the zoom more than I thought I would.

[apochronaut]

You can use the planachromat phase objectives on the Dyna . Just, I don't think I have ever seen a Dynazoom phase condenser come up for auction.

[BramHuntingNematodes]

Oh yeah been using that Tiyoda condenser and works sort of ok. The 10 annulur stop works with the.20x objective (apparent ly B&L and wild 20x.objective annuli are the same). The 40 stop works with the 40 object ive. A tiny little bit of condenser racking is needed, which is.tiresome, but it doesn't seem to sacrifice much of the image.

Here's a question: so the flat field dynazoom and Balplan turrets I have seen have "Flat Field" written on them. There is a very similar looking turrets condenser for the Dynoptic without thismlabeling. The manual says that the flat.field equipment is only for use for the flat field models and that objective and condenser are always shipped together. I know the objectives are specific to the flat field models, but are the condensers different aside from the lettering? I have a Dynoptic condenser in the mail and to be able to use.it. Should be.better or the same as the Tiyoda anyhow.

[BramHuntingNematodes]

Oh crackers I just realized it will have annuli for 21x and 43x not 20 and 40. Still, an improvement over the insert condenser for that set.

[apochronaut]

It is hard to determine what will happen in a non native objective once a phase annular diaphragm image passes through the condenser and gets focused. Having messed around with them quite a bit in AO systems, it seems that in order to get a reasonable phase match , even if you start with the same size diaphragm, the condenser focus itself must be precise, the condenser mechanical distances must be precise and the optical pathway to the phase plate in the objective must be very close to the original design parameters. Part of that last step includes the magnification of the annular diaphragm image up to the point in the objective that the phase plate lies. I don't have any B & L 160mm phase objectives on hand but I do have 38 AO and Reichert phase objectives and 4 Balplan objectives plus a few odds and sods of others.

My intuition tells me the B & L 160mm phase objectives would be very close to AO 160mm phase objectives in terms of the location of the phase plate in the objective. The size and composition might vary a bit but not by much. AO was half way around the track by the time B & L got up to the starting gate on phase and never caught up, so dollars to doughnuts, they had a complete AO phase system in their secret room of competitor's microscopes and modelled their first system quite a bit on it. So did Nikon, so did Olympus, so there need be no shame involved.

So, I have a Balplan phase condenser in hand and several AO phase condensers. The first thing that is of note is that AO only used an abbe condenser on their very early systems. Although not marked as such, the series 4 and earlier condensers seems likely a 1.25 abbe condenser but one with a specific very short rear focal point that fixes on the annular diaphragm only a few mm below it. You cannot bring one of their standard 1.25 abbe condensers into the system and have it work. Abbe condensers aren't the best at working dry. A 1.25 abbe is designed to be oiled but phase works at sub 1.0 N.A. levels for all objectives, so for their next act, AO built a 3 element in two groups dry achromat phase condenser, # 1242 of probably an N.A. of .90 or higher. It's specifications are undisclosed but I have examined it extensively and compared it to the later, # 1201 which is marked as a .90 achromat/aplanat. When oiled, each work at about 1.3 but the point of focus changes.

With the condensers, the B & L design and the AO design part company. B & L continued with a 1.30 abbe for the Dynoptic series and then used a 1.25 abbe aspheric for the Balplan. One similarity though, is thst both B & L in the Balplan condenser and AO in the series 10 condenser house a refocus lens below the phase diaphragms, presumably to bring the illumination beam to a longer focus at the annular diaphragms, since the phase condenser must have a short rear focus. An odd difference is, the annular diaphragms in the AO systems are relatively consistent in their increase in diameters from 10X through to 100X and the Balplan diameters are very similar to those in the AO condenser, except the 100X, which takes a big leap, being almost twice the diameter of the AO equivalent in the 160mm condenser. In other words, there is a huge difference between the diameter of the 40X Balplan annulus and the 100X. Going back to my postulàtion that the 160mm Dynoptic system would fairly closely resemble the 160mm AO system, the 160mm 100X B & L annulus might be much smaller than the diameter of the Balplan annulus.

Looking at various objectives, the phase plate in them is not always at the rear focal plane. Usually, yes but I have one objective where it occurs deep in a plan fluorite design, near to the front of the objective. Looking at the Balplan 100X planachromat, the phase plate as well is deep inside the objective, close to the front of the objective. The phase plate by comparison for the 20X planachromat is deposited on the last surface before the image leaves the objective, above the objective shoulder! This is all complicated by the fact that unlike the 160mm B & L objectives, the Flat Field and Planachromats magnify only 1/5 of their face value. The 100X is actually a 20X and so forth.

[BramHuntingNematodes]

Thanks-- sounds like this will be an experiment at best

[Element 56]

Nice lens Bram!

I have two one of which I rebuilt. It was dirty and the correction collar was seized. The other which is cosmetically the nicer of the two has some really bad delamination. One of these days I'll try to fix it!

Kirby

[apochronaut]

Kind of paints a bad picture of the old B & Ls. but it is unfair. So, I have been at this a while. 25 years ago, most of the objectives that came up for sale were good. I think I went through six or seven 45 and 47.5X B & L apochromats with maybe one dud amongst them. Same with 90X and the 20s. The weak one was the 10X |apochromat. The rear element is a doublet and it delaminates slightly developing Newton's Rings. The objective often still works o.k. but if bad enough there is a bit of contrast loss. It's just that there are only so many of them around . Good ones were sold as good and now there are some sitting around that are being passed off as untested, or as is, or no way to test.

[BramHuntingNematodes]

Yeah these are the only bad B&L lenses I have ever got, aside from a fluorite 43x from the 30s that has a slight loss of contrast due to some separation.

The 45x apo I got from a bike shop and so I was not too hopeful. The first bad 47x apo came as an afterthought to the complete B&L phase contrast set I bought along with the good 90x 1.4 NA so I wasn't going to make any fuss about it, and the second bad 47x I was able to return promptly. The 10x apo I have is the first one I ever saw and its fine. I think I paid $15 for it.

In addition to what you stated above, the old high-dry apos I think are especially desirable and grabbed after. Excessive force applied to stuck collars probably doesn't help either, especially in the bike shop I guess.

[einman]

I have a B&L APO 61x/1.4 immersion objective. It is dated Oct 13th 1925. I have not actually tried it as of yet. I seem to recall acquiring it from Apochronaut himself! Although not absolutely sure. He may recall better.

I have 2 extra Apo 47.5 x one with a frozen collar but both optics are excellent. I planned on working on the collar this winter. I extra 10x APO. Like yourself, I have the complete set mounted on a Dynazoom. They are quite good even if teh FOV is quite small compared to newer scopes. Still, the quality and resolution is incredible given the age of the scopes.

[BramHuntingNematodes]

Oh no, the apos are on the 1942 Dynoptic originally requisitioned for Hanford Engineer Works. The Dynazoom is a flat field model and has a 10x and 40x planachro, 20x planachro phase, and a 40x flat field phase. The 'zooms are great scopes though. The "flat field" mystique probably has kept their desirability and price very low, but if you got Apochronaut here to talk through setting it up they can't be beat!

[apochronaut]

Originally, B & L probably used Zeiss designs for their apochromats due to an alliance between George Saegmuller Co. , Carl Zeiss Jena and Bausch & Lomb, after 1907. Under this triple alliance each company had access immediately to any of the other's inventions or work. Early in W.W. I , Zeiss withdrew from the agreement and returned their 20% share in B & L and it seems after that , B & L emerged with apochromats. In 1926 a patent date was emblazoned on all of their objectives. It is hard to know what the reason for that was. It also coincided with the death of the founder, John Jacob Bausch.
After W.W. I, the U.S. gov't confiscated something like 4,700 German patents and licensed them to U.S. firms. You can bet that those Zeiss patents that B & L had been using during the war were part of that, and possibly others. Their subsequent stamping of Oct. 13 1926 as this grand date that all of their own patents took effect was some form of formal announcement that these were their designs and they were free to use them, despite some of them being wholly or partially based on someone else's work. Presumably, there was something that took place in U.S. law or between the U.S. and Germany that precipitated that action. I don't know of any other example where a company felt obliged to stamp a whole group of patents as having been granted on the same date on a whole range of microscope objectives. Perhaps it was to thwart a reciprocating threat from Zeiss. Afterwards, B & L apochromats become common.

From the early 20's on into the 50's, the research microscope market was largely held by both Spencer and Bausch & Lomb in North America. Spencer had delved into apochromatic designs around 1900 when Hermann Kellner came to work for them and worked on designs for apochromats. Examples exist of Spencer apochromats going back that far and they have little resemblance to Spencer apochromats produced during, shortly after the war and subsequently. Later compens eyepieces do not work on them well and the barrel lengths are somewhat different. During the 20's, Spencer objectives changed more into line with those of B & L but records exist showing that they were largely in house designs.

From about 1925 to 1955, although the barrel design and lettering changed slightly, the B & L apochromats changed little. They were a 16mm, 10X : 8mm , 20X : 4 mm , 45 or 47.5X : 3mm 61X or 62X : 2mm , 90X . The N.A.s of the 3mm and 2mm vacillated a little with a 3mm .85 collarless , .95 collared and 1.4 oil, all existing at the same early on but by 1958 only 4 objectives remained , a 10X .30, a 20X .65, a 61X 1.4 and a 90X 1.3.

The Spencer objective line was very similar but they changed more in their N.A. and magnification. The 2mm for instance began as an 82X and gradually crept up to 90X. They at one time offered a 1.5mm 1.30, that boasted 125X. The 8mm N.A. went from .58 to .65 later.

Spencer objectives generally have finer defenition than B & L apos but B & L , superior contrast.

Although Spencer's offerings were generally the same, they went through an evolution during that period, especially during the 1920's. The

[Element 56]

Kind of paints a bad picture of the old B & Ls. but it is unfair. So, I have been at this a while. 25 years ago, most of the objectives that came up for sale were good. I think I went through six or seven 45 and 47.5X B & L apochromats with maybe one dud amongst them. Same with 90X and the 20s. The weak one was the 10X |apochromat. The rear element is a doublet and it delaminates slightly developing Newton's Rings. The objective often still works o.k. but if bad enough there is a bit of contrast loss. It's just that there are only so many of them around . Good ones were sold as good and now there are some sitting around that are being passed off as untested, or as is, or no way to test.

Agreed! Unlike Zeiss I have found very few B&L objectives with delamination. I would add Spencer, AO and Leitz to that list.

I would be hard pressed to spend the big money on some of those vintage Zeiss lenses because of the delamination issue. Just shipping them through the mail or cleaning them could be fatal!

Kirby

[einman]

No When I said "like yourself" I was referring only to having a set of the apos. I saw you were referring to a Dynoptic rather than a Dynazoom. I should have been more clear. The Dynazoom/Dynooptic scopes could have various bodies and objecive options. I have a Dynopotic with the flatfield objectives as well as one with the regular achros. Apochronaut assisted me in the past in obtaining various objectives and condensers for these scopes.

[BramHuntingNematodes]

Oh crackers I just realized it will have annuli for 21x and 43x not 20 and 40. Still, an improvement over the insert condenser for that set.

I never followed up on this but in fact, the older B&L turret condenser is a very good fit for the flat field and planachromat phase objectives, maybe on purpose. I was able to use the 21x setting for the 20 planachromat and the 43x setting for the 40 flat field objectives while the condenser is in the approximate Kohler position. I say approximate because about an eigth-to-a-quarter turn upward is useful for the 20x objective.