MicrobeHunter.com Microscopy Forum

I was reading some interesting information on the German Mikro-Forum concerning the different Zeiss DIC configurations. In one of the posts, the author noted that the front lens of the 1.4 NA condenser was immersed in water. Is this commonly done for all of the older Zeiss DIC configurations (I have the original one with the slider III and the condenser with the DIC prisms)? For doing water immersion, do you use distilled water and do you use immersion for all objectives? Any notes on applying the water to the front lens of the condenser would be appreciated. Thanks in advance for the information.

Hi,
Zeiss said to use oil immersion on the condenser front lens at all magnifications for your DIC system. Water immersion comes close to oil immersion and it works dry too, but of cause with drawbacks. When using immersion make sure that no fluid enters the fine thread that attatches the top lens. Water could cause corrosion and oil could gum up, time depending on the type of oil.
I use demineralized water from the food store, in a 100ml bottle with a dropper.

Bob

Bob, would you have a rough idea or guidance in immersing the Zeiss condenser to the slide (dry vs. water vs. oil) at something like 25x and 40x magnifications -- or even lower? Does water help? Oil significantly more?

Hi Pete,
I have never compared that methodically. Since changeing back and forth is time consuming one would have to take photos with switched of automatics to really compare the results.

Bob

PeteM wrote: ↑

Tue Dec 08, 2020 10:57 pm

Bob, would you have a rough idea or guidance in immersing the Zeiss condenser to the slide (dry vs. water vs. oil) at something like 25x and 40x magnifications -- or even lower? Does water help? Oil significantly more?

If you do the trig calculation for internal reflection at air-glass interfaces you will find that in air (so no oil or water) a 1.4 NA condenser is limited to about 0.9-0.95 NA. This is perfectly fine for objectives up to that NA, so adding oil to an otherwise dry 20-40x objective won't do anything useful. I've only even seen a difference when using a 63/1.4 Planapo while inspecting the objective back focal plane. There if I don't add oil the cone of illumination does not fill out the objective aperture. The image is a bit dimmer but unless I look at a critical object like a diatom test plate I do not notice a difference in resolution. Since you know the refractive index of water you can calculate the resolution you can get substituting water for oil.

I do use water on the condenser when I do darkfield microscopy with objectives up to 40/0.75

Hi Wes,
do you use the DIC system with the single analyser slide or the newer one with individual analyser slides pe robjective?
The old system doesn't allow the use of the full objectives aperture anyway.
Zeiss specifically sait to use oil immersion even for the low power objectives. This might be a perfectionists view (Zeiss ) but there will be a reason for this statement. I don't know how the polarized light influences in this case too.

Bob

Wes wrote: ↑

Wed Dec 09, 2020 7:33 am

I do use water on the condenser when I do darkfield microscopy with objectives up to 40/0.75

Interesting ! use water instead of oil for darkfield - I like it ! do you think it will work well with the 40X1.0 (iris oil objective) as well ? I mean, oil between the objective and coverslip, water between the condenser and bottom of slide, for DF ? and how about the same replacement (water vs oil) with the Ultrafluar condenser ? { note - the Zeiss manual claims that the D darkfield position of the turret phase-contrast condenser is equivalent to the Ultrafluar - I found a slight difference).

MicroBob wrote: ↑

Wed Dec 09, 2020 8:02 am

Hi Wes,
do you use the DIC system with the single analyser slide or the newer one with individual analyser slides pe robjective?
The old system doesn't allow the use of the full objectives aperture anyway.
Zeiss specifically sait to use oil immersion even for the low power objectives. This might be a perfectionists view (Zeiss ) but there will be a reason for this statement. I don't know how the polarized light influences in this case too.

Bob

I use the new system with individual prisms. This is the first time I hear you need to oil the condenser with the old system for all objectives irrespective of magnification. But what would be the rationale for that I wonder..

Hobbyst46 wrote: ↑

Wed Dec 09, 2020 10:54 am

Interesting ! use water instead of oil for darkfield - I like it ! do you think it will work well with the 40X1.0 (iris oil objective) as well ?

For the dry 40/0.95 objective the background losses a significant portion of its darkness when using water with the D darkfield position which is why I limit the NA to 0.75 . I think you have to try it and see but if the dry planapo is anything to go by for comparison the 40/1.0 planapo would probably lose some of the darkness.

Wes