160TL 60x-100x water iris objective

[zzffnn]

Dear all, I am looking for an 160mm tube length water immersion objective at 60x -100x range that has an iris aperture of around 0.7-1.2. One that doesn't cost over $500 USD used.

Please let me know what brand, magnification, NA and other eBay search keywords. Thank you very much.

As I also have an AO series 10 infinity microscope, I would even consider an infinity objective of similar spec and cost. But this would be an optical mismatch most likely, since AO Spencer has not made such an objective.

I do have a LOMO 30x water iris 0.6-0.9 and enjoy it very much. Unfortunately, I don't think LOMO ever made a water iris objective of higher magnification. LOMO did make an oil iris 60x and many other brands offered 50x-100x oil iris objectives (which I have 4); but. those are not what I want this time.

[viktor j nilsson]

That's quite an attractive set of features.

The Zeiss Plan Neofluar 63x 1.2 W Korr is pretty much the only one thing that comes to mind, but it doesn't have an iris:


I think it will be almost impossible to find what you are looking for.

[apochronaut]

For a reason I haven't figured out, the AO #1026 50X .85 with iris, works quite well as a water immersion objective. On the other hand, the #1016 50X .80 planachro with iris does not.
Although the # 1026 works best with oil , the difference between oil and water with that objective is very slight. Quite probably, the objective could be improved in it's performance with water immersion by altering the shimming internally, something quite possible with other objectives too.

Something I have considered but probably will never find the time to do, is make a nosepiece with an embedded iris diaphragm. The Bausch & Lomb Balplan would be ideal for that kind of modification because they made a collar of about 1" depth that sparated the nosepiece from the head in orde to give enough clearance to reverse the nosepiece, if so desired. That is why you see Balplans with both conventional and reversed nosepieces. Since the back lens for each objective is common and in the nosepiece throat, that collar does not lengthen the optical tube since it is in the infinity space.

You might consider looking into older 37mm Leitz offerings. I'm sure they had some high magnification W.I. objectives. Their idea for an iris was unique in that it was housed in an upper non optical section. Many objectives pre- W.W. II had quite compact optical sections which were housed in the lower "optical" section of the objective. The objective was often split, and the optical section was threaded into a spacer section which contained the threads and established the parfocal length. Leitz offered a common spacer section containing an iris that could be threaded into more than one objective.It came as an accessory in their Condensor für Dunkelfeld kit, instead of the funnel stops that others used. You see them on ebay sometimes.

[zzffnn]

Thank you, gents.

Phil, I have #1016, facepalm. I do need variable iris NA between 0.8 and 1.2 though.

My purpose is to use objective iris to instantly switch between NA 0.8 DIY darkfield and DIY COL, along with a phase turret condenser with DIY masks. Turning iris at bright field condenser didn’t work as well (not at all for DF and not very well for COL).

Oil objective iris between 0.7-1.25 worked beautifully for that purpose. I only need a water iris version.

My alternative is putting two of the same LOMO water immmersion 65x NA 1.1 apo objectives on the same nose, then use one for COL (by turning condenser iris to match different mask sizes) and use the other with DIY modified darkfield funnel (that Phil, Rick and Kirill kindly helped me make a few years ago).

[zzffnn]

Thank you very much, Phil.

I have seen Leitz water objectives, but not the objective internal “spacer with iris”. Besides searching for “Leitz Dunkelfield“, are there other search keywords I should use on eBay?

Balplan is attractive to me, but I have run out of desk and garage space for yet another big scope. Did Blaplan ever have a high NA water immersion objective (is it unicorn rare)?

[apochronaut]

The Leitz iris isn't an internal spacer. It is the upper blank or spacer section of an objective and can be threaded into the optical section of numerous Leitz objectives. It just contains an iris and an objective so modified looks just like any other iris equipped objective. It may be possible to fit it to other older objectives, as long as the optical section of them has a female thread. The male thread on it looks to be 13mm x .5 tpm.

The Balplan comment was more rhetorical. For your purposes there may be another more appropriate stand. It's just that I have considered that mod.on a Balplan because I have a fantastic prototype 125X 1.40 oil Flat Field Apochromat. The only iris equipped objective for that system is the 100X 1.25 planachromat and as good as that objective is : I am blown away by the 125X. Having an iris capability with it is a goal I have.
Bausch & Lomb abandoned W.I. during their 160mm era. I'm sure you know the ones they made.
Once Cambridge Instruments became the boss sometime around 1980, the consolidation of effort across the B & L and AO stable became paramount and the quirky Balplan clearly lost out to the AO series 400, so further development was iced. They no doubt might have included the possibility of w.i. objectives had the program been funded for continuance.
However, water immersion correction is just a shift in the spacing between certain elements in the objective, similar to that with a correction collar, thus a multi-immersion objective functions similarly. Theoretically, some oil immersion objectives could be altered to water immersion by changing specific internal shim set: front element to second lens grouping primarily.

Here is an interesting thing. Look up patent US198914A, given to Ernst Gundlach around 1878 who at the time worked for John J. Bausch and Henry Lomb. Gundlach had not been a prosperous business man in Germany. Brilliant as an inventor but he couldn't add up Marks very well. Bausch & Lomb allowed him the freedom to invent and not have to worry about accounting.
That's an interesting objective, since it is the original patent for the correction collar.
I have a Bausch & Lomb First Class 1/12" 1.4 N.A. homogeneous immersion with an original funnel stop. It is 1 5/8" parfocal or about 40mm, so different than what B & L eventually settled on for their 160mm tube microscopes. This one is an 8.5 " tube, which was also a common early tube length. The objective is brand new but probably dates from shortly after the patent, around 1880. Doesn't have a scratch on it's iridium front lens housing. The patent says that a liquid such as glycerin needs to be placed between the cover glass and the front glass of the objective, which is not a lens, more a corrector plate. Since it has a correction collar, the liquid being used could be many, possibly any between water and immersion oil, so this also might be an early incidence if not the first incidence of a multi-immersion objective.

The actual correction collar rotates from left to right beginning at 0 to 9 and back down to 0 over 180° and then continues through 1 and back to 9 over 162° to stop. The entire 342° rotation drives the lower section of the barrel including the correction plate about 1/2mm downwards.
When I get a minute, I will post some photos.
The second picture shows 100 years of Bausch & Lomb and 3 different parfocal systems and tube corrections, modified infinity, 8.5 in. and 160mm

[zzffnn]

Phil,

I guess I just have to wait for the Letiz part. The following is a thread-in funnel (not an iris) and costs too much: https://www.ebay.com/itm/265265549822?_ ... 2&LH_BIN=1

The patent that you mentioned is very interesting: https://patents.google.com/patent/US198 ... =US198914A

[apochronaut]

Here are some photos. The Leitz condenser kit does pop up, occasionally. I would sell you this one but currently I have plans for it. That could change.

[zzffnn]

Phil,

Do you know any Leitz water objective that is compatible with that part? Is yours silver or brass in color? This eBay item
Looks like yours but has a n immersion lens top and is silver in color: https://www.ebay.com/itm/265526328733?h ... SwDgNh919H

So that Leitz part is called “IRTIS”. Basically a modified “Davis shutter” that is designed to be be inserted further down, closer to lens pack (which is theoretically better).

One Leitz catalog called “IRTIS” an “intermediate objective adapter with iris diaphragm”. I don’t know if that “intermediate” means that IRTIS is designed for medium power objective or that it is designed to be inserted in between.

I have seen about 6 older 160TL Leitz water objectives: 10/0.25, 22/0.65, 20/0.60, 25/0.65, 90/1.2 and 100/1.2. I don’t care about the low power objectives. For the two high power one, neither looks like it would screw onto IRTIS though, because it doesn’t appear to have an outside thread at the right location.

There are many conventional “David Shutter” type nosepiece iris, but they change tube length and parfocal height and thus are very inconvenient to use. Not to mention the iris would be further away from objective lens pack as well, which is supposedly not ideal optically.

[apochronaut]

I believe Irtis was the Goddess of Confusion.. Depending on how much her irtis was open, the confusion lessened or greatened. Yes, it threads in fairly close to the lens pack. I have used it with 1.30 achromat and it works well. I think Leitz would have designed it such that if it threads in, it should work. Otherwise, the Goddess of Confusion owned Leitz.
I'm not sure where you are going with this. You speak of an AO 10 , infinity, so the location of Irtis can be many and she thrives in all but you are really looking for 160mm , right?

[zzffnn]

Thanks, Phil.

Iris deals with the circle of confusion, doesn’t it

Leitz did really spell it as IRTIS. I am not sure why.

The thing is, neither of the two high power Leitz WI objectives seem to have a thread at the right place for IRTIS to thread in; though I could be wrong as I am only guessing by looking at their online photos.

I like AO10, but there is no high power water iris objective for it, unless I use a different brand that may not optically match. My main scopes are 160TL. So AO10 is only a backup option for the future, if and only if I can find an affordable infinity water objective.

[apochronaut]

The only one I know of that works well as a W.I. is the #1026 50X .85. ...not something I can easily explain. There is barely any difference when using oil or water and it has an irtis.
For the short tube 160 objectives. I will trial a B & L iris equipped 90X 1.30 apochromat as a W.I. for you. One never knows , perhaps with a quartz cover?

[apochronaut]

There are those free standing iris diaphragms on ebay of all sizes. AO made numerous attachments for the 10 that fit into the infinity space. One or more of those could be adapted to receive an iris in it's port with some method of external activation. There was a simple spacer for instance. Iris in the center and perhaps a cable control. Or a gutted bertrand lens unit. The iris could be permantly fixed in the center and controlled through the existing channel in the side that is used to flip the lens in and out and focus. Might even be able to use the existing flip control to move the iris.

On the 4, that isn't as easily possible but the compensating lens above the nosepiece becomes the back focal plane of the objectives, so I could see installing an iris right above that ; it's a nice secure location and rigging up a short cable control should not be too hard. Bicycle cable. I'm not 100% sure on this one but it seems plausible.
That way you can call up irtis at your disposal.

[zzffnn]

Thank you very much, Phil.

[Rossf]

Hey zzffnn you might want to look out for this zeiss one-37 parfocal 63x .85 W.I I recently got from a German seller-I love this objective! No iris though. The immersion cleans up the softness that little bit of air between objective and slide introduces in a dry high 63x and I like how it’s a ‘normal’ n/a meaning more depth of focus than a 1.2 etc-I haven’t tried it with high n/a darkfield condenser but I expect if the condenser is n/a 1.2 than it should give good darkfield-I’ll try to cram in a test an post a photo-BTW I’ve got that lomo 30x W.I also-it’s crazy sharp! And I’ve used it on an Olympus CK-1 inverted and gives a nice image without immersion…it’s a keeper.
Good luck

[zzffnn]

Thank you, Rossf. I am looking for water iris around NA 1.1-1.2 though. Otherwise no point, as I have pretty much all other features, such as NA 1.1 WI, NA 0.7-1.32 oil iris, etc…..