Nikon Labophot Manual de instrucciones - Página 11

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The graduation on the Abbe condenser indicates

the diameters in mm of the aperture diaphragm

opening of condenser ..

After removing the eyepiece from the eyepiece

tube, adjust the size of the diaphragm, observ-

ing the image of the diaphragm which is visible

on the bright circle of exit pupil of objective

inside.

It is recommended to take note of the diameter

of the diaphragm opening for each objective

power, whereby the best image is obtained.

The

Swing-out

Achromat

and

Achromat/

aplanat condensers, however,

have

a graduation

indicating the numerical apertures (N.A.l. and

not the diameters of diaphragm opening.

Manipulation of these condensers is the same as

that of the Abbe condenser. Stopping down the

aperture diaphragm too far will deteriorate the

image quality of microscope due to diffraction

of light. Therefore, it is not recommended to

stop down the aperture to a size smaller than

60% of the N.A. of the objective in use except

when observing almost transparent specimen.

6) Use of field diaphragm

The field diaphragm is used for determining the

illuminated

area on the specimen surface in

relation to the field of view of the microscope.

Generally, it is stopped down to such an extent

that the circumference of the illuminated area

circumscribes or inscribes that of the eyepiece

field of view. If the former be larger than the

latter, extraneous light will enter the field of

view, causing flare in the image and lowering

the contrast.

Therefore,

especially in photo-

micrography, the proper adjustment of the field

diaphragm is very important.

Generally, good

results will be achieved when the diaphragm is

stopped down to such an extent that the dia-

meter of illuminated area is slightly larger than

the diagonal of film format.

7) Focusing

The relation between the direction of rotation

of the focus knobs and that of vertical move-

ment of the stage is as indicated in Fig. 14.

One rotation of the fine focus knob moves the

stage O.2mm.

The graduation on this focus knob is divided

into

2J.Lm.

One rotation of the coarse focus knob moves

the stage 4.7mm.

The range of coarse and fine motion is within

30mm;

2mm up and 28mm down from the

standard position.

Tightness of the coarse-fine focus knob having

been properly

adjusted by the manufacturer,

it should never be readjusted in this model

microscope

by turning

the one knob while

holding the other.