Swift M3500 SERIES, Manual

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3.  While viewing through the eyepiece, rotate the coarse focusing knob 

to bring the specimen into view.    Next, sharpen the focus using the 
fine focus knob.

4.  If the image of the specimen appears pale, the aperture of the 

diaphragm should be decreased (if the model has a disc diaphragm, 
rotate the disc to a smaller hole, conversely, if the model has the iris 
diaphragm, it should be closed slightly).  This will increase contrast 
in the specimen’s image.    If the specimen appears dark, slightly 
open the diaphragm.     

5.  Rotate the nosepiece to the next higher  power objective. A slight 

turn of the fine focusing knob may be required to bring the image of 
the specimen into sharp focus. Once the specimen is in focus with the 
highest power objective, it will be in focus with each lower power 
objective. 

OIL IMMERSION (Only for models with a 100X objective) 

When light rays from the objective lens to the specimen pass through air, 
they are distorted slightly, a phenomenon known as refraction. This is 
usually not a problem at a magnification of 400X or lower. However, at a 
magnification of 1,000X and above, refraction becomes problematic.   
This problem is reduced significantly by placing a thin layer of very clear, 
viscous oil between the slide and tip of the objective lens. The result is a 
much clearer image at 1,000X because the oil has the same light 
transmitting properties as glass. Using oil slightly increases the 
resolution and brightness of the image. Usually a very thin slide (size #1) 
is used for oil immersion because at this magnification, the working 
distance is very small and is critical to focusing the specimen. Good 
quality glass (not plastic) cover slips should be used. If their thickness is 
over 0.17mm, the objective will not resolve properly, because the 
specimen cannot be moved close enough to the objective lens to be in 
focus. 
 
Place a tiny amount of oil (only 1 drop should be sufficient) onto the slide 
prior to rotating the 100XRD objective into position. It is essential to 
thoroughly clean the objective tip after use to prevent damage and to 
ensure that an image can be seen clearly the next time the objective is 
used. Please contact Swift Optical or your authorized Swift dealer for the 
appropriate immersion oil to use.