Centering & adjusting the Leitz 100Z lamp?

[Rorschach]

Hello,

How do I center and adjust the lamp on a Leitz 100Z lamp when there is no adjustment disc?

Disc and procedure shown here:

Leitz_adjustment_disc.jpg (45.59 KiB) Viewed 1534 times

[Rorschach]

Further investigation revealed that the lamp condenser (to the left from the bulb) seems to be pretty misaligned. Isn't that supposed to be standing straight and not tilted like in the photo?

20240323_143843.jpg (99.56 KiB) Viewed 1523 times

[Alexander]

A centering disc is easily made DIY. Just print it on semi-transparent paper. The exact dimensions are not critical at all.

The lamp condenser is clearly defective. It must be centered on axis to work properly.

[MichaelG.]

Hello,

How do I center and adjust the lamp on a Leitz 100Z lamp when there is no adjustment disc?

You should be able to make a replacement disc from a sheet of tracing paper or similar
… it’s just a target; the screws do the adjustment.

MichaelG.

.
Alexander beat me to it !!

[Rorschach]

Thanks. I was able to realign the lamp condenser. It is straight now, not tilting. Also made a DIY target from a circular frosted glass filter. I think I was able to center the lamp according to the instructions in the 100Z user manual.

Then I tried setting up the 402a Zernike condenser that I have on the Orthoplan to enable using darkfield, according to the instructions below (from leaflet/manual Leitz phase contrast equipment after Zernike). However, I can't get the field diaphragm visible. Stuck at that step. What could it be?

Leitz_402a_darkfield.jpg (136.9 KiB) Viewed 1505 times

Seems like the condenser flip-up top lens was the culprit. After I flipped it out of the path, the field diaphragm became visible. However, it doesn't look like a clean circle like in the manual, but more rough and asymmetrical. Also, a lot of red (inner) and yellow (outside the red) around the dark spot that appears (couple steps forwards in the instructions). Something is amiss, I guess.

Another question: with the condenser height adjusted as high as it will go, there is still about a centimeter between the (flipped up) top lens and the bottom of the subject slide. Is this normal? I'm trying to figure out whether the stage (a Leitz as well) is not compatible with the condenser.

Here are photos showing the distance of the condenser top from the slide, and one below the stage:

20240323_162839.jpg (105.35 KiB) Viewed 1497 times

20240323_162857.jpg (97.65 KiB) Viewed 1498 times

[Rorschach]

Based on what I read of Leitz 600 and 400 series condensers, their intercept distance with the flip-up top is around 1.2mm, please see below. Doesn't this mean that my problems are likely caused by the condenser not reaching a high enough position, close enough to the slide? Please see the photo I posted above.

Leitz_400_series.jpg (110.72 KiB) Viewed 1422 times

[MichaelG.]

Is your Orthoplan a standard instrument, or a ‘bitza’ ?

[ bitza this, and bitza that ]

It looks to me like you need to first make some reasonably simple measurements of what your illumination system is actually doing … and then compare with those listed values.

Note particularly the reference to IV at the bottom of your most-recently posted table.
… Those Adapter lenses are important to the proper working of some stands.

MichaelG.

[Rorschach]

It's a bitza.

Turns out that the stage is not incompatible with the condenser and it's rack. Instead the condenser rack was mounted too low and it was stuck there. There is a thumbscrew on the right side of the condenser rack that, when loosened, let's the condenser mount slide properly up. This resolved that problem. After that I was able to better get the field diapragm in view while doing the Köhler procedure of centring and focusing. Was also able to center the phase discs in the condenser turret. However, still not able to center the darkfield stop in the turret.

[Rorschach]

It's a bitza.

Turns out that the stage is not incompatible with the condenser and it's rack. Instead the condenser rack was mounted too low and it was stuck there. There is a thumbscrew on the right side of the condenser rack that, when loosened, let's the condenser mount slide properly up. This resolved that problem. After that I was able to better get the field diapragm in view while doing the Köhler procedure of centring and focusing. Was also able to center the phase discs in the condenser turret. However, still not able to center the darkfield stop in the turret.

The adapter lens 4 would be the appropriate one for the Orthoplan but from what I have read elsewere, it is not an absolute necessity, rather an incremental benefit or plus to have.

[Hobbyst46]

On a proper setup, the condenser top lens should be able to nearly touch the slide bottom - within less than a millimeter. At least, to allow oiling the condenser to the slide for oil immersion imaging. However, the geometry of the stage and condenser carrier could allow the top lens to emerge too much upwards, then it pushes the slide from below, above the stage surface, and the slide pops out form the holder. On my (non-Leitz) microscope, there was a tiny stopper screw at the top of the condenser carrier, supposedly to limit the upwards travel of the condenser. I suspect that the screw is non-original, some replacement, and had to remove it to be able to raise the condenser as high as necessary for DF, immersion, etc.

[Rorschach]

On a proper setup, the condenser top lens should be able to nearly touch the slide bottom - within less than a millimeter. At least, to allow oiling the condenser to the slide for oil immersion imaging. However, the geometry of the stage and condenser carrier could allow the top lens to emerge too much upwards, then it pushes the slide from below, above the stage surface, and the slide pops out form the holder. On my (non-Leitz) microscope, there was a tiny stopper screw at the top of the condenser carrier, supposedly to limit the upwards travel of the condenser. I suspect that the screw is non-original, some replacement, and had to remove it to be able to raise the condenser as high as necessary for DF, immersion, etc.

Yeah, I am aware of these now, the hard way It's frustrating that things like this are not mentioned even in the proper Orthoplan manual, not even in the assembly sections. In some other instructions there are also minor things omitted, causing headaches sometimes.

[Alexander]

Based on what I read of Leitz 600 and 400 series condensers, their intercept distance with the flip-up top is around 1.2mm, please see below. Doesn't this mean that my problems are likely caused by the condenser not reaching a high enough position, close enough to the slide? Please see the photo I posted above.

The condenser holder can be moved up and down. Your is likely to far down. Just slide the entire holder upwards into a proper position.

This is an Orthoplan! Everything on it could be adjusted.

[Rorschach]

Based on what I read of Leitz 600 and 400 series condensers, their intercept distance with the flip-up top is around 1.2mm, please see below. Doesn't this mean that my problems are likely caused by the condenser not reaching a high enough position, close enough to the slide? Please see the photo I posted above.

The condenser holder can be moved up and down. Your is likely to far down. Just slide the entire holder upwards into a proper position.

This is an Orthoplan! Everything on it could be adjusted.

That was the problem, yes. The 'normal' vertical adjustment of the condenser using the knob worked perfectly, but the initial level of attachment that in a way sets the limit of travel available (how high the condenser can be raised) was way too low. And the control screw for that was stuck, leading me to initially hesitate meddling with it.