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I recently obtained a Carl Zeiss Epi Condenser/Illuminator system for my GFL body and am learning how to use its various components. The condenser I have id the H_PI and the objectives are EpiPlan HD’s. Illumination has been converted to LED.

I think I have identified the darkfield slider (1), the ND filter (2), filter slot (5) and the field diaphragm (7). What I do not understand, and can’t find in the manuals I’ve looked at, is what the roles for the levers marked 3 and 4 and the lever marked 6 are. Moving lever 6 shifts the field diaphragm laterally, perhaps for an oblique effect. The pair of levers marked 3 interact with the movement of lever 4 and seem to change the shape and orientation of the illuminated field.

I would be very grateful if someone could direct me to a manual for this device or could help me fill in the blanks in my understanding.

thanks

michael

Hi Mike,
I have a similar but probably a bit newer illuminator. From the filter slots behind (1) it is just a lamp, all complicated stuff has been simplified away!
Perhaps you can find the functions if you look into the back, point the condenser with or without objective towards a moderately bright light source and see what happens when you operate the controls. I would guess that the epi condenser controls are similar to those of a bright field setup: A field iris, a condenser aperture, and a centering mechanism. This probably becomes clear when you actually put the thing into use.

Bob

Hi MikeBradley,

First, nice to find that I am not the only user of a Zeiss Standard GFL here !

Second, I am not familiar with this specific epi-illuminator, yet in general, all epi-illuminators are supposed to provide Kohler illumination. The epi configuration means that the objective simultaneously functions as condenser; but aperture diaphragms must be there, and I assume that knobs 3 and 4 (or at least one of them) serve that purpose. Indeed, a pair of nearby irises is found on other epi-illuminators, including modern ones (like the BX51 for example).

EDIT: in the GFL manual, they say that the various epi-illuminators can be found in Zeiss leaflet no. 40-650. Hopefully it can be retreived. Some Zeiss leaflets from that era are inaccessible.

Thanks for your responses John and Hobbyst46. I've been doing some further investigating and I now realise that in my original image I had identified the field diaphragm and the iris diaphragm incorrectly, their functions were reversed. I did look for the leaflet suggested by Hobbyst46 with no luck but I did find an section on Zeiss Epi-condensers in the Zeiss Photomicroscope manual (G 41 - 656 - e) on page 42 and that has answered many of my questions.

One remaining question concerns polarisation. When I place linear polarisers in the filter slot/inside the trinoc head I get the polarisation effect, but with a red/magenta background, the same colour that I see on other systems when a full wave retarder is in place. The two swing in filters are out of the light path and I removed the darkfield slider with it's clear window. What could be causing this effect?
Thanks for any help

Michael
Michael

MikeBradley wrote: ↑

Fri Mar 05, 2021 10:26 pm

One remaining question concerns polarisation. When I place linear polarisers in the filter slot/inside the trinoc head I get the polarisation effect, but with a red/magenta background, the same colour that I see on other systems when a full wave retarder is in place. The two swing in filters are out of the light path and I removed the darkfield slider with it's clear window. What could be causing this effect?

A wild guess: With the epi-illuminator, light passes twice through the polarizer, as follows:
from the light source ->beam-splitter->polarizer-> objective->specimen, and the reflected light from the specimen travels back through the objective, polarizer and beam splitter vertically into the eyepieces. In addition, reflected light (from glass) is polarized to some extent. Perhaps the combined effect gives the magenta color ?

Maybe a waveplate up in the head assembly Zeiss is always putting stuff up on the head assembly

BramHuntingNematodes wrote: ↑

Fri Mar 05, 2021 11:55 pm

Maybe a waveplate up in the head assembly Zeiss is always putting stuff up on the head assembly

There is indeed a lens in the objective turret of the Zeiss Universal, but not in that of the GFL or WL. The latter is just an empty mechanic connector.

As I mentioned earlier, when the polariser is under the stage and the anaylser is in the trinoc head, I can get total extinction. Using the same film, but placing it in the epi light path, I get only partial extinction, almost as if a retarder plate is in the path. Same effect whether LED or Tungsten light is used. The objectives I use are the HD style and the reflector is the simplest one, the H-Pi. Could the effect that I'm seeing be partial de-polarisation of the Epi light? The Photomicroscope manual that I using for info. on this condenser does make reference to a de-polarisation limitation for this reflector design. Perhaps the partial extinction is how it manifests?
Thanks for your thoughts.
Michael

Yeah hmm those HD objectives do bounce the light off of a metallic mirror perhaps some phase shift is induced. You could unscrew the reflector all the off to see if this might be the case but don't lose that set screw gosh it's tiny ! You probably also would need a.good stereo scope with some strong radial or coaxial illumination to peer into there to see where the threads were previously marred. Lot to go through to test a supposition