Changing the Zeiss 47 17 61 flourescence epi-illuminator condensor on the Zeiss IM microscope

When I purchased my Zeiss IM inverted microscopy just over one year ago, there was no epi-fluorescence condenser present. I purchased one off ebay (Zeiss part 47 17 61 – in this post I will call it the EFC). Unfortunately, the filter slider was stuck. Luckily another in full working condition came up very cheaply recently and I have now replaced the first one. However, the technique for taking one out and putting in another was not obvious so this post is to record the process for future reference, should I or anyone else want to make this change on the Zeiss IM or IM35 microscope (both use same component). I will probably wish to do this myself. After I find a way to fix the stuff filter slider, I also have a Zeiss IM35 and will probably put the spare one on that, although epi-fluorescence requires use of the fluorescence cube for the microscope and I only have one of those and they are quite expensive second hand, so I doubt I will be acquiring a second one soon!

It is worth noting that the EFC provides epi-illumination but was only designed to be used for fluorescence microscopy. I am hoping to adapt the fluorescence filter cube to remove one of the filters and replace with plain glass so that I can use it for more general epi-illumination. Today’s project was the first step in this process as it allowed me to slide out of the way a blue filter in the filter slider which was stuck in the light path. In fact this needed to be done prior to the removal of the old EFC and – given that the reason for Today’s project is that it was stuck – this required the use of a hammer to be achieved! I was gentle and put something between hammer and microscope with softening covering (spare piece metal coveted in kitchen absorbent roll) and managed to succeed without causing further damage, although my heart was in my mouth while I did it.


Zeiss 47 17 61 epi-flourescence condenser  (EFC). This is the one that I removed today. You will notice that there is one slight difference between this one and the new one I installed in its place, which is shown in the later photos on this post – the adjustment screws for centering the illuminator light are longer in the new version. These can be seen in the later views from the back of the microscope.

Back of microscope – epi-illuminator is central round bit. The illuminator will be attached here (not attached in this photo):

The following pictures show an illuminator attached to the back of the Zeiss IM35 microscope. It is the square box hanging off the back, opposite the eyepieces (oculars). It would be exactly the same with the IM microscope as the only difference between the two varieties of microscope is that the IM35 has an inbuilt camera port whereas the IM does not have one.

View of epi-fluorescence condenser (EFC) from next to the eyepiece turret. This view shows the filter slider within the epi-fluorescence condenser component that was stuck on the first one I installed on the microscope. The epi-fluorescence condenser comprises both the white and black round parts on left side of the picture. The black part is seen to contain a circular filter holder with small black handle. This can be removed. For installation of the whole component or taking it out again, both the filter slider and the round filter holder need to be removed. This allows the whole component to then be slid out through the hole in the casing on the left – that hole is currently obscured by the black circular component which sits over it.

The the following photo shows the EFC from the other side. The long thin silver metal handle controls the aperture control within the EFC. To install or remove the EFC from the microscope, this handle must be first removed so that the EFC can slide out through the hole, otherwise it will obstruct it. The handle is removed by twisting it anti-clockwise, which will unscrew it from the EFC.


1. Start at back of microscope.

2. Locate the four retaining screws on the back which hold the etc In place and remove them.

3. Unscrew and remove long thin handle.

4. Locate and remove tiny screw from end of filter slider. This screw prevents filter slider being removed from EFC. Once screw is remembered bed, slide filter slider completely out of the EFC.

5. Remove content recluse filter holder (left below) from EFC. Note in this picture, filter slider is also shown as present but of course by now you will have already removed that in previous steps.


6. By now the EFC should be quite loose. Note it only pushed again eyepiece turret and not attached to it so there are no screws etc that need to be loosened there. The EFC should now be easy to thread through the hole in the back of the microscope and removed.

7. Insert new EFC by reversing the above.

Illuminator for epi-illumination during fluorescence microscopy with Zeiss IM/IM35 microscope

This is the illuminator I have obtained which fits on the epi-illumination port at the back of the microscope: Zeiss part 46 72 59 – 9901. This is the illuminator which is meant to be used with a mercury lamp for fluorescence microscopy.

It is quite a heavy bit of kit and like everything that fits on these microscopes made of metal and built like a tank!

The following link opens a manual which seems to work for this illuminator, although I am not sure whether it is exactly the right one:

Zeiss Illuminator 100 user manual (PDF file)


The next picture shows a small Allen head screw in the central depression on the bottom of the illuminator. Loosening this (does not need to be completely removed) allows the lamp and its base to be slipped easily out of the housing for examination +/- replacement:

The next pictures are of the lamp that is in the illuminator – this came with it when I purchased it from ebay:


I think this is a new version of the lamp above:

100W appears to be the correct rating for this illuminator as noted on the underside of the lamp base:


Can you work out what this is? Seen through Zeiss IM microscope by epi-illumination

Epi-illumination is where light shines onto the object rather than through it (trans-illumination) & is useful for looking at solid objects through the microscope. One way to achieve epi-illumination is by a system that projects light through the objective onto the object – a difficult thing to achieve and usually requiring a good quality lab microscope. First success today with this on my Zeiss IM microscope.

Can you work out what the following object is?


32x objective = ca. 320x magnification:

Pictures above show the object has radial marks from a circular structure on the left and second picture shows irregular dents in the structure. Are these features related or unrelated to each other?

x20 objective = x200 magnification:

Regular linear markings appear in the first picture at this lower magnification, giving a tile-like appearance to the object. However, photograph 2 shows a hill-like structure.

x4 objective = 40x magnification:

This picture reveals that the hills come in fours (see top left) and form part of a fort-like outline. What could cause this?

The culprit is shown below……

x1 magnification:

A Malaysian coin.

The microscopic images are of a small cross at top of the central peak on the crown.