Centering a Zeiss circular stage

[tlansing]

In a thread on this forum (viewtopic.php?f=5&t=6115&p=89593#p89593), 75RR provided a method for centering a circular stage on a Zeiss microscope (see below)

75RR's Instructions and Figure:
In order to centre the stage we need an eyepiece with a reticule (cross hairs) and a slide that contains a subject that we can focus on,
say a stage micrometer for example though any slide with something that can be focused on it will do.
Chose an identifiable item within the field of view near the middle of the slide (33-1).
Imagine a straight line from it to the centre of the cross hairs.
Move it halfway along that imaginary line towards the cross hairs using the stage centering screws (33-2).
Then, using the stage slide controls, move it the rest of the way, exactly to the centre of the cross hairs (34-1)
Rotate the stage 180 degrees and repeat the steps.
Do this as many times as you need to until the subject rotates on its own axis when you rotate the stage (35-2).

Stage-centring-diagram.jpg (34.29 KiB) Viewed 604 times

Although I don't have a eyepiece reticle, I do have a micrometer slide so I thought I would try this procedure. I chose the object to focus on as the end of one of the lines on the micrometer slide. Following the instructions, I used a centering screw to move the object toward the approximate middle of the field of view (I have only one of the centering screw wrenches so I switched back and forth between the 2 centering screws to move the stage). When I began to rotate the stage, the focus object swung completely out of the field of view. I tried rotating the stage only slightly and then repeating the centering instructions but this did not help because the focus object continued to swing completely out of the field of view. I'm not sure how to proceed, so any suggestions would be greatly appreciated. Thanks!

Tim

[KurtM]

Howdy Tim! I love the Zeiss rotating biological stage so much I've adapted a couple of them to my Oly BH-2s, and center them almost constantly since they need re-centering with objective changes. I've never used a reticle eyepiece or any other aid, just do it by eye. My method is to center a target in the FOV, usually just a speck or whatever that's easy to keep track of, then rotate the stage enough to see the arc my target speck describes while keeping it within the FOV, and extrapolate-imagine it into a circle and adjust the two stage centering screws to bring that imaginary circle's center point towards the center of the FOV. Rinse and repeat until centered. Practice makes perfect. I can usually center the rotation in two or three of the above steps and it only takes seconds.

I machined small knurled thumb knobs for the stages that didn't come with them and required wrenches, which remain permanently attached, and I consider them indispensable. If you don't have the machinery to make a set, I can provide you with a set, although it'll be June before I'm back home and can get to it. They're made of aluminum so the look is tolerably original, and the softness of the material allows them to simply press fit on. No charge.

[mineral rob]

When centering either a stage or objective and you don’t have a cross hair reticule and only a scale, pick the center most point on the scale. For example, if you have a horizontal reticule (ie: scale of 1 to 10) pick the line for 5 where it crosses the horizontal and use that as your center ‘cross-hair’ point. Then follow 75RR’s steps above.

Depending on how par-centered the objective positions are to each other you should be able to center to your highest magnification first and the others may end up close to centered. It is microscope dependent, and is why petrographic polarizing microscopes have individual objective centering turrets on them in addition.

[Hobbyst46]

...I love the Zeiss rotating biological stage so much I've adapted a couple of them to my Oly BH-2s...

That is interesting, KurtM ! the Zeiss stage is attached to the Zeiss Standard stand with four screws arranged in an arc. Did you drill through the BH-2 stage carrier ? is the thickness of the BH-2 original stage the same as that of the Zeiss stage ?

[KurtM]

Here you go: viewtopic.php?t=9924

[Hobbyst46]

In a thread on this forum (viewtopic.php?f=5&t=6115&p=89593#p89593), 75RR provided a method for centering a circular stage on a Zeiss microscope (see below)

75RR's Instructions and Figure:
In order to centre the stage we need an eyepiece with a reticule (cross hairs) and a slide that contains a subject that we can focus on,
say a stage micrometer for example though any slide with something that can be focused on it will do.
Chose an identifiable item within the field of view near the middle of the slide (33-1).
Imagine a straight line from it to the centre of the cross hairs.
Move it halfway along that imaginary line towards the cross hairs using the stage centering screws (33-2).
Then, using the stage slide controls, move it the rest of the way, exactly to the centre of the cross hairs (34-1)
Rotate the stage 180 degrees and repeat the steps.
Do this as many times as you need to until the subject rotates on its own axis when you rotate the stage (35-2).

Although I don't have a eyepiece reticle, I do have a micrometer slide so I thought I would try this procedure. I chose the object to focus on as the end of one of the lines on the micrometer slide. Following the instructions, I used a centering screw to move the object toward the approximate middle of the field of view (I have only one of the centering screw wrenches so I switched back and forth between the 2 centering screws to move the stage). When I began to rotate the stage, the focus object swung completely out of the field of view. I tried rotating the stage only slightly and then repeating the centering instructions but this did not help because the focus object continued to swing completely out of the field of view. I'm not sure how to proceed, so any suggestions would be greatly appreciated. Thanks!

I just re-checked it with a Zeiss rotating stage on a Zeiss Standard microscopes and it works exactly according to the steps described by 75RR.
The potential pitfall of the Zeiss setup, IMO, is that it is easy to erroneously touch and turn the CONDENSER centering thumb-screws instead of the STAGE centering thumb-screws and vice versa - because the two pairs of thumb-screws look very similar and are similarly positioned on the rear-low side of the stage.

[KurtM]

That's right, I also turn the wrong screws every once in a while - argh! Another good reason to get practiced and comfortable re-centering the stage (and condenser too!).