OPERATION
Axio Observer Using objectives ZEISS
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5.3 Using objectives
The selection of objectives co-determines the fields
of use the microscope can reasonably cover. An
objective might carry the following labeling:
N-ACHROPLAN 20x/0,45 ∞/0,17
Key:
20× Objective magnification, with a color ring on the microscope objective allocated to each
magnification step (ZEISS color code)
0.45 Numerical aperture
∞ Infinite tube length
0.17 can only be used with cover slip thickness D = 0.17 mm.
or
– can be used without cover slip (D = 0 mm) or with cover slip thickness D = 0.17 mm
0 can only be used without a cover slip (D = 0 mm)
Further abbreviations:
HD Reflected light objective for brightfield and darkfield
DIC can be used for Differential Interference Contrast
Pol can be used for polarization contrast
Oil Immersion objective for oil as immersion medium
EC Enhanced Contrast
LD Long distance
i insulated
iHMC improved Hoffman Modulation Contrast
LCI Life Cell Imaging
alpha Aperture > 1.4
Objective magnification color coding:
Color ring on
objective
black brown red orange yellow green light blue dark blue
white
Magnification
factor
1.0x;
1.25×
2.5× 4×; 5× 6.3× 10× 16×;20×;
25×; 32×
40×; 50× 63× 100×;
150×
The objective magnification (e.g. 10x) multiplied by the eyepiece magnification (e.g. 10x) and the Optovar
magnification (e.g. 1.6x) yields the overall visual magnification: for example: 10 x 10 x 1.6 = 160x.
The numerical aperture x 1000, e.g. 0.20 x 1000 = 200x, is the highest useful magnification. No further
detail will be resolved above this limit.
Immersion objectives are fundamentally less sensitive to differences in cover slip thickness.
With immersion objectives, the air between the cover slip and the objective is replaced with a liquid,
usually immersion oil.
Fig. 80 Objective labeling
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