Leica DM IL (searching for correct set up info)

[microb]

Hi,

I have a Leica DM IL (black print on the sides, no red decorations) and only an overhead light, type 090.131.001. Basically no lower lamp and no dichroic mirror in the base.

The binocular head is the "Made by Leitz Portugal 512 821/20" with the eyepieces being Leitz PERIPLAN GF 10x/20 M. If that's an invalid set up, please let me know.

What objectives for phase contrast would work with this? It came with a 160 4x Leica (519759), but the binocular most likely has an infinity focus tube lens. Is it actually a 160?

So before I buy parts, can someone confirm the what objectives to get. I'd like to test it for phase contrast. Also do the eyepieces need to be a particular correction type for the recommended objectives? I don't know of any correcting relay lens for Leica DM** series, except that the DMR's had magnifier turrets built in, so I always assumed lateral chromatic correction took place there. The trinoculars never had the Olympus like NFK relay lenses, but maybe that's a mistake on my part regarding older models.

Thanks.

[microb]

So the Leica DM IL 001 version, has two lenses to extend the 160mm TL path. I still don't know how an inverted moving objective turret for focusing, works with a non-infinity focus objective. I thought the magnification would change slightly while focusing.

So the green lines show the light path through a slightly disassembled Leica DM IL.

[Scarodactyl]

Very confusing. I have limited leitz experience, but didn't think there was much compatibility with later Leica scopes. All the documentation I have found (via quick googlin') suggests the dm il takes standard Leica 25mm infinity objectives, but this one apparently has a Leitz 160 (rms) mounted?

Given when Leica was formed, I would be surprised if they did any finite compound systems, but I really only know the stereo side in detail.

Edit: I guess the Galen III was Leica and 160mm, though it was not made by them and not really related to other offerings.

[microb]

Taking Nikon's Diaphot inverted microscope which uses 160mm objectives, the stage is raised and lowered for focus. If the objective turret moves, that must mean the microscope is inifinity focus, others the distance to the camera changes, so the focus is wrong.

So is this Leica DM IL an infinity focus? I'm still looking for the manuals, but the objectives everyone sells with it are 160mm. Of course someone also is selling one with a 170mm.

Did Leica put a 160mm to infinity lens inside? Maybe lens 1 in the diagram creates collimated light, and lens 2 is a magnifier or lateral chromatic adjustment?

Any info or pointers would be appreciated.

Thanks.

[PeteM]

A system with finite objectives can have either the nosepiece or stage move for focus. As an example, my finite Olympus CK2 has the nose move. What matters most is the relative distance between the specimen and the objective; which varies by just tiny fractions of mm for parfocal-designed objectives.

In my limited experience with inverted scopes, most of the relatively new ones move the nosepiece. It's better to have the stage stay in place for ergonomics, stage stability (easier & cheaper to accurately move a small nosepiece than a large stage), and the addition of accessory equipment (e.g. electrophysiology probes, special dishes, etc.).

[microb]

Hi PeteM,

Yes, for inverted the nose piece on infinity focus moves and on fixed length the stage moves. I'm trying to understand this microscope where the nose moves, but the objectives that always get sold with it (possibly incorrectly) are 160mm.

I'll try to get the lamp running here and experiment with it soon. But if anyone knows what this Leica DM IL 090.131.001 is doing, any information would be appreciated.

Thanks.

[Brad_]

I know nothing about your microscope but the head and eyepieces
were standard equipment on the 160 TL Diaplan,

If you think it would help I could mount the Diaplan's beastly
phase condenser and a Leitz 160 TL objective on another 160 stand
but I'm sure it will give a decent image. This won't preclude
Leica from having sneaked in some 160 to infinity optics.

Have fun.

Brad

[microb]

Hi Brad,

Thanks for mentioning the binocular head.

So I'm still hunting for info on how moving a 160mm objective works for focusing.

I found the design patent for a slightly later model. So still looking.

https://patents.google.com/patent/USD354299S/en

[Scarodactyl]

Not different from focusing by moving eyepieces up and down.

[microb]

So the design inside has light shooting down through the 160mm objective:
1. hits a mirror to shoot towards the front
2. goes through a plano-convex doublet lens (convex side first, exiting planar side)
3. enters penta-prism to orient image and shoot upwards
4. goes through a matching doublet (planar side first)
5. then up to the binocular/trinocular head.

Collimated lights shooting into the planar side, appears to focus at around 160mm, measuring somewhere mid-lens thickness.