5
3. Focusing the microscope.
A. Position the 4x objective lens into the optical path, making sure that lens is properly indexed in its click-stop position.
B. Swing moveable finger on specimen slide holder outward. Place specimen slide (cover slip up) on top of stage surface
against fixed side of slide holder. Slowly release moveable finger until it makes contact with specimen slide.
C. Rotate coarse focusing controls until specimen comes into focus.
D. Adjust fine focus controls until specimen is in sharp focus.
E. Adjusting the aperture (opening) of iris diaphragm.
Iris diaphragm should not be used to control the brightness of illumination, use the illuminator light intensity control to
adjust light level. Iris diaphragms are designed to help achieve high resolution of specimen and provide contrast in the
image. Smaller apertures will deliver higher contrast to image. However, closing aperture too much will reduce
resolution. Experimentation is the best method of determining the correct opening of diaphragm. Some suggested
openings for iris diaphragm are:
OBJECTIVE
DIAPHRAGM OPENING
4x
From fully closed to 1/8 open
10x
1/8 to 1/4 open
40x
1/4 to 1/2 open
100x
1/2 to 3/4 open
F. Usage of special built-in neutral filter.
a) Placing a filter into the optical path will absorb some of the light from the illuminator base, limiting the light output.
b) When using 4x and 10x objectives the special neutral filter must be in optical path.
c) When using the higher power 40x and 100x objectives remove filter from optical path.
d) To remove filter, grasp filter holder knob and swing out filter holder.
G. Changing magnification.
a) Rotate revolving nosepiece to position 10x objective into optical path.
b) This microscope has been parfocalled, which allows changes from one objective to another while requiring only a
slight adjustment of the fine focus controls.
c) When changing to the 40x and 100x objective lens, care must be exercised when positioning these lenses into the
optical path, in order to prevent damaging the front lens element and specimen slide.
d) In order to obtain maximum resolution of the 100x oil immersion lens, it is necessary to apply immersion oil between
the cover glass of slide and front lens of the objective.
(1) Use of a very small amount of immersion oil is required.
(2) All air bubbles must be removed from between lens and slide by gently rotating nosepiece back and forth.
(3) When finished viewing, all parts that come in contact with oil must be cleaned. Failure to do so could
permanently damage the 100x oil immersion objective lens. Use Windex to clean immersion oil off lens surfaces
is recommended.
Objective Specification Chart
Objective
N.A.
Color Code
Ring
Field of
View
Working
Distance
Magnification with
WF10X eyepiece
Din 4X
0.10
Red
4.5mm
26.4mm
40X
Din 10X
0.25
Yellow
1.8mm
5.5mm
100X
Din 40X
0.65
Blue
0.45mm
0.48mm
400X
Din 100X
1.25
White
0.18mm
0.06mm
1000X
