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| How to Use the Stereo Zoom Microscopes |
This document refers to the Zeiss SV8 and Olympus SZH stereo microscopes (Note 1). Operationally, they differ in how the eyepieces are focussed. The beginning of this document is stated as recipes, the details section that follows is referred to with note numbers.
HOW TO FOCUS THE EYEPIECES The eyepieces have their own focus mechanisms to adjust them to your eyes (Note 2). The strategy is to first adjust the eyepieces without focussing on a sample, then to focus on the crystal (etc.) without further adjusting the eyepieces. The focus for the thing to be examined is adjusted with the focus knob (see below), not the eyepieces.
It is best to start with the lamp on, but nothing on the stage. If you usually wear glasses, then wear them to focus the eyepieces. Relax your eyes so that they focus very far away. Without re-focusing your eyes, look through one eyepiece that contains a reticle. Rotate the eyepiece until the reticle comes into focus. For the Zeiss microscope with a camera, repeat the process for the other reticle.
For the microscopes with only one reticle, focus the reticle eyepiece as above, then place a razor blade on the microscope stage. Make sure that the aperture is all the way open (Note 3); turn the dial (Zeiss) or move the slider (Olympus) on the front of the microscope to the maximum open position. Looking only through the reticle eyepiece, iteratively move the sharp edge into the center of the field of view, focus on the sharp edge using the focus knob (see below), and increase the magnification to its maximum by rotating the magnification knob (see below). Without touching the focus knob, rotate the other eyepiece to focus on the sharp edge. When doing this for the Zeiss SV8 microscopes that we have, keep the blade straight from front to back (Note 4).
HOW TO FOCUS First, focus the eyepieces to your eyes, as described above. Then focus on the crystal (etc.) with the focus knob. The focus knobs are the ones without numbers that stick out the sides of the microscopes (Note 5). It's in focus when it has sharp edges (Note 6).
HOW TO CHANGE THE MAGNIFICATION The magnification knobs are the ones with numbers on them that stick out the sides of the microscopes (Note 7). Rotate towards larger numbers to make the image larger, towards smaller numbers to make it smaller (Note 8).
CLEANLINESS The optical surfaces of the microscope may be cleaned with lens paper (Note 9) wrapped around a cotton applicator, then dampened with the ammonia version of Windex (Note 10). Wipe with a gentle circular motion. Do not rub with any force. DO NOT USE KIMWIPES ON OPTICAL SURFACES (Note 11). The optical surfaces may be wiped dry with lens paper.
NOTE 1 These microscopes cost upwards of $8,000 each. The one with a camera cost twice as much. A lot of people depend on them. One of the Zeiss eyepieces ($600 each) is severely scratched. Please be careful!
NOTE 2 What prompted all this typing is that the eyepieces are being abused. The eyepiece focus is to be used for slight correction of users' individual vision. If you need more than about 0.5 diopter, you should be wearing glasses or contact lenses. There is apparently someone among us with about a 6 diopter DIFFERENCE between (his?) left and right eyes. The eyepieces are frequently forced against their limits so hard that they are difficult to bring back into their proper operating range. Please do not force the eyepieces!
NOTE 3 Microscope resolution works the same as x-ray diffraction resolution. High angle scatter (aperture open all the way) results in high resolution. The resolution limit in practice is limited by our requirement that we can fit our hands between the stage and the objective lens; the maximum scatter angle isn't much in these microscopes. See also Note 6.
NOTE 4 Our Zeiss SV8 microscopes are equipped with dual objectives. The focal planes are tilted. Simultaneous focus for both eyes can be achieved only along the line of intersection between those two tilted focal planes. Therefore, the razor blade has to go through the center of the fields of view, oriented straight from front to back. See also Note 6.
NOTE 5 The Zeiss microscope with a camera on top is pretty heavy, and the focus consequently feels heavy. Don't force anything! If anything other than that one focus knob is hard to turn, there is something wrong, and we need to call for repairs.
NOTE 6 Well ok, you focus by minimizing blurriness. You can see the resolution limit by focussing on the sharp edge of a razor blade at maximum magnification. The image has a green or magenta fringe depending on which eye is looking and which way the blade is oriented. The blade is in focus when the color fringe is minimized.
NOTE 7 Don't force the magnification knobs. When you feel the stop, then stop. Don't try to rotate past the stop. Same story for eyepieces.
NOTE 8 The overall magnification is calculated by multiplying all the magnification numbers together. The Zeiss SV8's have 1x objective lenses. The magnification when looking through the Zeiss microscopes is 1 times the number on the magnification knob times the magnification on the eyepiece (16x). For photography with the Zeiss camera, the image size on the film is the number on the magnification knob times 12.5 times 0.25. The camera has a 0.25x lens. The maximum magnification onto the film is therefore 1 x 6.4 x 12.5 x 0.25 = 20. The calculation is similar for the Olympus microscope, except that it has a rotating objective turret with 1x and 1.5x objectives.
NOTE 9 DO NOT USE KIMWIPES ON OPTICAL SURFACES!!!!!!!!!!!!!!!!! Lens paper is very smooth, lint-free, and doesn't scratch soft optical glass. The world's best lens cleaners are microfiber cloths, but such would be opticide in a lab full of gorillas.
NOTE 10 Not the acidic version of Windex, which is corrosive to the lanthanide oxide coatings on the glass, and to the metal parts. Removal of vacuum grease requires something like ethanol and many lens papers, but be very careful not to drip. The objective lenses are cemented together, and the cement would be severely damaged by exposure to anything organic. The objective lenses get splattered during violent acts of crystal mounting. Please be careful.
NOTE 11 DO NOT USE KIMWIPES ON OPTICAL SURFACES!!!!!!!!!!!!!!!!! Optical glasses and their coatings are pretty soft.