Objectives - Zeiss Axioskop 40 Operating Manual

Carl Zeiss
Fig. 1-1 Objective
Other labels:
Oil : oil immersion objective
Ph 2 : phase contrast objective with a green color ring and phase stop Ph 2
Color ring code for objective magnification:
Color ring on black
objective
Magnification 1.25x
factor
Objective magnification multiplied by eyepiece magnification (usually 10x) results in overall visual
magnification: e.g. 10 x 10 = 100x.
When working with the microscopes, total magnification should not drop below or exceed the range of
useful magnification. The range of useful magnification was defined by Ernst ABBE as 500 to 1,000
times the numerical aperture of the objective used . There is no resolution for further details above that
limit. Accordingly, the range of useful magnification for an objective with a numerical aperture of 0.25 is
between 125x and 250x.
Exact observance of the cover slip thickness of 0.17 mm is all the more necessary the higher the
numerical aperture of the objective. For this reason, certain objectives can be set to different cover slip
thicknesses (due to correction mount). To this end, a specimen area is searched for, and the position of
the correction ring where optimum focus and image contrast are obtained is determined (refocusing is
invariably required).
1-8
INSTRUMENT DESCRIPTION

Objectives

brown red orange
2.5x 4x; 5x 6.3x
1.4 Objectives
The objectives are the optical heart of the
microscope. The following is an example of how
objectives can be labelled:
Achroplan 10x/0.25 ∞/0.17
where
10x : objective magnification, with a defined
color ring on the objective being allocated
to each magnification step (Zeiss color
code)
0.25 : numerical aperture
∞
: infinite image distance; these objectives
can only be used with ICS microscopes
from Carl Zeiss
0.17 : can only be used with cover slip thickness
D = 0.17 mm
or
−
: can be used with cover slip thickness D = 0
or 0.17 mm
yellow green
10x 16x;20x;
25x;32x
Axioskop 40
Axioskop 40 FL
light blue dark blue white
40x; 50x 63x 100x;
150x
B 40-810 e 12/01