USING THE COARSE FOCUS SET SCREW - 100F/100FL

 

The MI-100F and MI-100FL student compound microscopes are equipped with a coarse focus set screw.  The height at which the microscope stage can be set and locked.  This is useful to stop the objectives from hitting the slide.

 

If this set screw is not set correctly it will prohibit the high magnification objective (40x) from being focused correctly.

 

The following procedure will detail how the set screw is used and tips for adjustment.

                                                                                                                                                      

 

This set screw (with a knurled siliver locking nut) is located on the microscope stand, behind the stage of the microscope.  When these microscopes are tested and given their final inspection at Micro Imaging, the set screw is set and locked as follows:

 

 

 

 

 

 

 

1.  The microscope's fine focus knobs need to be set in the middle of the "fine focus run" (there may be 20 revolutions of the fine focus knobs from the beginning to the end of the run).  Take the fine focus to an end of its run (either end will do).  The fine focus knobs are then rotated back 10 revolutions (i.e. in the middle of the "fine focus run").

 

2.  With the 10x objective rotated into place, the slide is focused using the coarse focus knobs.

 

3.  The coarse focus set screw is then screwed down (in a clockwise direction) until it hits the internal focus block and cannot be screwed down any further.  The knurled silver locking nut is then screwed down (in a clockwise direction) to lock the screw into place.

 

4.  Focusing can now be done (at each magnification) by using just the fine focusing knobs, rather than the coarse focusing knobs.  As the objectives on the MI-100F and MI-100FL are "parfocal", only a few turns of the fine focus knobs are required to focus the specimen, at each magnification.

 

TIP: The above procedure may not take into account varying thicknesses of glass slides and coverslips. Our recommendation is to set the coarse focus set screw 0.5mm higher than usual for these possible variations.

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