Standard 25
ICS
1-6
B 40-029 e 01/98
1.4 Objectives
The objectives are the optical centerpiece of the microscope. The following is an example of how
objectives can be labelled:
CP ACHROMAT 10x/0.25
/-
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 tube length
-
:
can be used with cover slip thickness D = 0 or 0.17
or
0.17
=
can be used with cover slip thickness D = 0.17
and
Oil
=
oil immersion objective
Ph 2
=
phase contrast objective with a green color ring and phase stop Ph 2
The objective magnification multiplied by the eyepiece magnification (minimum 10x) results in the visual
overall magnification, e.g. 10 x 10 = 100x.
The numerical aperture x 1000, e.g. 0.25x1000 = 250x, is the highest useful magnification, i.e. no
further details are resolved above that limit.
The objective labeling
indicates that these objectives may only be used with microscopes
featuring an infinite tube length and not with instruments the objectives of which are marked
with "160" as their mechanical tube length.
The exact observance of the cover slip thickness of 0.17 mm is all the more necessary the higher the
numeric aperture of the objective. Therefore, so-called "Corr" objectives can be set for different cover
slip thicknesses via a correction ring. For this, a specimen area is searched, and the position of the
correction ring where optimum focus and image contrast are obtained is determined (refocusing is
always required).
Immersion objectives are always insensitive to differences in cover slip thickness.
When immersion objectives are used, the air between the cover slip and the objective is replaced with a
liquid, which is immersion oil in most cases. The plastic oiler containing 20 ml of 581 N immersion oil is
particularly suitable for this purpose.
Due to their short working distance, objectives 25x and higher feature resilient mounts (specimen
protection). To prevent oil contamination of the specimen when the nosepiece is turned, the resilient
mounts of the immersion objectives can be locked in their lifted position by turning them to the right (do
not forget to unlock them again!).
Summary of Contents for Standard 25 ICS
Page 1: ...Standard 25 ICS Transmitted Light Microscope Operating Manual...
Page 22: ...Standard 25 ICS 2 2 B 40 029 e 01 98...
Page 30: ...Standard 25 ICS 3 2 B 40 029 e 01 98...
Page 46: ...Standard 25 ICS 4 2 B 40 029 e 01 98...
Page 56: ...Standard 25 ICS 4 12 B 40 029 e 01 98...
Page 58: ...Standard 25 ICS A 2 B 40 029 e 01 98...
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