Zeiss Phase Contrast Condenser question

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FredH
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Zeiss Phase Contrast Condenser question

#1 Post by FredH » Mon Jan 23, 2023 10:30 pm

I have a Zeiss Standard with Phase Contrast, which I bought well-used from a university. It has a turret condenser as shown below.
Condensor_top_smaller.JPG
Condensor_top_smaller.JPG (68.93 KiB) Viewed 2186 times
The condenser turret has seven apertures, labeled J, 1, 2, 3, 4, 5, D. J is the iris seen at 6 o'clock in the photo below. Counterclockwise 1, 2, 3 are Ph1, Ph2, Ph3 (verified by viewing with centering telescope and aligning the mask annuli with the phase rings in objectives with Ph1, Ph2, Ph3. D is the darkfield stop.
IMG_0311Zeiss_turret_smaller.jpg
IMG_0311Zeiss_turret_smaller.jpg (161.67 KiB) Viewed 2186 times
My question: what are the masks in positions 4 and 5? 4 is an annulus intermediate in diameter between Ph2 and Ph3 -- what is this used for? 5 is an annulus bigger in diameter than Ph3 -- what is this used for?

Thanks for any insight.

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imkap
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Re: Zeiss Phase Contrast Condenser question

#2 Post by imkap » Tue Jan 24, 2023 10:00 am

I don't know, but can only guess in the absence of other answers.

Maybe if you remove the top lens and switch to one with lower NA (or use without) these would match with something at lower mag. This may or may not make sense. I have a similar condenser with flip top lens (with empty 1,2,3) but unable to try what happens as I don't keep it at home...

Or there are some objectives from an another manufacturer which would match the annuli. Although they look like Zeiss made...

Hobbyst46
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Re: Zeiss Phase Contrast Condenser question

#3 Post by Hobbyst46 » Tue Jan 24, 2023 11:45 am

Zeiss publication "Zeiss Optical Systems" describes some models of the 7-port turret condensers.
Usually some of the ports are left empty, probably for custom configuration.

One model (the achromat aplanat 1.4) of the phase contrast condensers contains J, D, Ph2, Ph2, and three empty ports.
Another model (the 0.9) contains J, Ph1, Ph2, Ph3 and three empty ports.
Yet another achromat-aplanat 1.4 model, named the "Achromatic-aplanatic phase-contrast fuorescence condenser 465278", is said to contain J, D, Ph2, Ph3 and two additional annular diaphragms for polarized light.

Possibly yours is a custom configuration, where the previous user installed polarization filters and/or annuli to make some use of the otherwise empty ports.
A lottery win would have been if your condenser contains DIC components. I am afraid it does not, since such condensers are clearly marked with arrows on the top panel.

Note that, for darkfield, the condenser top lens should be oiled to the bottom of the slide - at least for the 40X and higher NA objectives.

FredH
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Joined: Sun Sep 04, 2022 7:45 pm
Location: Wisconsin

Re: Zeiss Phase Contrast Condenser question

#4 Post by FredH » Wed Jan 25, 2023 2:20 am

Thanks for the suggestions.

I just tried holdng a linear polarizer (polarized sunglasses) in front of the two additional annuli, with no noticeable effect from rotating one or the other. So whatever the two annuli are, they apparently don't contain linear polarizers.

I'm not sure a condenser with some DIC components would be a lottery win -- then I'd have to start trying to obtain the other components to make a DIC system. I bid on the microscope (without a chance to inspect it) at a University auction, and got it for a good price. It looks like all it needed was some cleaning and greasing. That's probably as close to a lottery win as I'll ever get.

Thanks again.

Amoeba X
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Re: Zeiss Phase Contrast Condenser question

#5 Post by Amoeba X » Sat Nov 04, 2023 8:31 pm

When I disassembled the condenser a tiny metal ball fell out. I assume it is for indexing the turret because without it the turret turns freely. Unfortunately I don't see an obvious place for the ball, suggestions greatly appreciated.

I am missing the knob and bracket shown in the last picture above- maybe that locks the turret?

Hobbyst46
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Re: Zeiss Phase Contrast Condenser question

#6 Post by Hobbyst46 » Sat Nov 04, 2023 8:50 pm

Amoeba X wrote:
Sat Nov 04, 2023 8:31 pm
When I disassembled the condenser a tiny metal ball fell out. I assume it is for indexing the turret because without it the turret turns freely. Unfortunately I don't see an obvious place for the ball, suggestions greatly appreciated.

I am missing the knob and bracket shown in the last picture above- maybe that locks the turret?
The tiny (~2.5mm diameter) ball sits on top of a tiny spring within a "well". It is for indexing, indeed. The ball can be affixed to the spring with a small drop of grease, during reassembly of the condenser.

The knob and turret serve to align the phase rings. Tightening the knob locks the phase alignment, indeed.

Amoeba X
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Re: Zeiss Phase Contrast Condenser question

#7 Post by Amoeba X » Sat Nov 04, 2023 8:57 pm

Got it, thanks so much! Assembly took a few tries but working perfect now. As for locking the alignment I'll have to do without and just be careful not to bump the alignment arm once set. I just bought the scope and am still (clumsily) feeling my way about. Thanks again!

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