Maintenance - National 211 Instructions Manual

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9. Changing magnification.
a. Magnification is changed by rotating objective turret until a different objective lens is moved into optical path.
Always turn turret until you hear the "click", indicating that lens is properly indexed. Otherwise, you will not be able
to see anything when looking through the microscope.
Objective
Din 4X
Din 10X
Din 40X retractable
Objective
Din 4X
Din 10X
Din 40X retractable
Din 100x retractable
b. Also note that each objective has a color ring, which permits you to instruct changes in magnification by referring
to an easily observed color rather than to a number.
c. The microscope has been parfocalled at the factory, which allows easy change from one magnification to another,
requiring little or no adjustment of the fine focus knobs.
d. As magnification is increased, the field of view (area of specimen seen through the microscope) will decrease.
That is why it is easier to find the specific area of interest on the specimen by starting with the lowest 4x objective
lens, before increasing magnification with the higher power objective lens.
e. NOTE: Care must be taken when rotating the 40x and 100x objective lenses into place. These lenses have a
spring retractable mechanism, which retracts slightly into its housing if the front of the lens, strikes the specimen
slide. With fine focus adjustment at mid-range, the rack stop has been adjusted at the factory to assure the 40x
and 100x lens will clear the thickness of a normal specimen slide and cover slip. However, if the rack stop has
been improperly adjusted, or if using a thicker than normal slide or cover slip, moving the 40x and 100x lenses too
quickly or carelessly could cause damage to the front lens element or to the slide. Remove swing out filter from
optical path when using the 40x and 100x objective lens.
f.
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. Use a very small amount of immersion oil. All air
bubbles must be removed from between lens and slide by gently rotating nosepiece back and forth.
When finished viewing, all parts that come in contact with oil must be cleaned. Failure to do so could permanently
damage the 100x immersion objective lens.
Do not let the front lens element of the 40x objective lens come into contact with a wet slide surface, as prolonged
contact with any moisture could damage the lens. If lens is exposed to moisture, promptly wipe with soft tissue to
remove moisture.

MAINTENANCE

211/212: For your own safety, turn switch to OFF position and remove electrical plug from power source.
211-RLED/212-RLED: For your own safety, make certain that battery recharger is unplugged and removed
from microscope jack before maintaining your microscope.
1. OPTICAL MAINTENANCE
Do not attempt to disassemble any lens components. Consult a microscope service technician when any repairs not
covered by instructions are needed.
Prior to cleaning any lens surface, brush dust or dirt off lens surfaces using a camel hair brush. Or use air to blow dust
and lint off surfaces. Use of compressed air in a can, available at any computer supply store, is a good source of
clean air.
Model 211/211-RLED Objective Specifications
N.A.
Color Code
Ring
0.10
Red
0.25
Yellow
0.65
Blue
Model 212/212-RLED Objective Specifications
N.A.
Color Code
Ring
0.10
Red
0.25
Yellow
0.65
Blue
1.25
White
WARNING
Field of
Working
View
Distance
4.5mm
18.5mm
1.8mm
6.4mm
0.45mm
0.5mm
Field of
Working
View
Distance
4.5mm
18.5mm
1.8mm
6.4mm
0.45mm
0.5mm
0.18mm
0.06mm
5
Magnification with
WF10X eyepiece
40X
100X
400X
Magnification with
WF10X eyepiece
40X
100X
400X
1000X

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