This is description of this part:
VERY (!) rarely encountered on the used market special Epi / Met microscope objective made by Carl Zeiss Jena.
Basic information:
Product: microscope objective
Manufacturer name: Epi-Objektiv 18x/0.30 Trockensystem Tubus unendlich, 1940
Name used before 1940: Epi-Objektiv 9.7 Epi, 18 Met Trockensystem Tubus unendlich, 1937
Thread: due to measurement inaccuracy I provide: 11 mm or 11.5 mm
Additional: the objective includes an insert that fits the EPI illuminator
Magnification (so called magnifier magnification): 18x
Numerical aperture: 0.30
Oil immersion: NO (dry objective)
Focal length: 13.8 mm
Compatibility:
- Carl Zeiss Jena EPI reflected light condenser W
- Carl Zeiss Jena EPI reflected light condenser WK
- Carl Zeiss Jena Metalliput metallurgical microscope
- Carl Zeiss Jena Met Mi IX metallurgical microscope
This unusual objective has a narrow special thread, but with the use of an intermediate ring with correction lens it can also be used on a standard microscope stand (e.g. Carl Zeiss Jena Lg).
When this objective is used on the Carl Zeiss Jena Metalliput microscope with an infinity corrected tube (in practice the tube length there is 250 mm), the full magnification of 18x is obtained.
When this objective is used together with a reflected light condenser (with an additional intermediate lens in the tube, that is with a 160 mm tube length) the concave mirrors partially extend under the objective, therefore the free working distance cannot be fully utilized. In such a configuration the real magnification is about two times smaller, approximately 9.7x.
Epi / Met objectives produced in the years 1937-1939 have two numbers engraved on the housing: 9.7 Epi, 18 Met.
a) the smaller value applies when used with the EPI condenser (correction lens focal length = 160 mm)
b) the larger value applies to the magnification obtained when the objective is used with the metallurgical microscope (correction lens focal length = 250 mm).
In 1940 the method of marking magnification on the objective housing was changed and only the "magnifier magnification" and the numerical aperture value were provided.
Information: the source of this information is the website of the Zeiss company archive. This information is provided in order to spread knowledge about rarely encountered microscope elements.
What is this part needed for?
- If you have a suitable microscope or EPI illuminator and this is exactly the objective you are missing
- If you have such an objective but it is damaged or of very poor quality
- If you have such an objective but the adapter for the EPI illuminator is missing
- If you would like to have such a rare objective in your collection
