Micron Optics - Nikon Microscope Systems for New Jersey and Puerto Rico
Use of the Correction Ring on the Objective
1. Measure or estimate the thickness of the coverglass or bottom glass of the culture dish. Set the value by the correction ring of the objective. This is typically 1mm for plastic dishes or looking through the bottom of a slide, and 0.17mm for a #1 coverslip.
2. Focus on the specimen image by the focus knob of the microscope. In this case, open the aperture diaphragm (N.A.) larger than the N/A. of the objective being used.
3. If the resolution (sharpness) and contrast of the image are not good, slightly turn the correction ring left or right. If the image is out focused by this correction, refocus on the specimen using the fine focus knob.
4. When the image quality is found better, slightly turn the correction ring further in the same direction for exact focusing. Repeat this procedure until the highest image quality is attained. On the contrary, if the image quality is found to be inferior, turn the correction ring in the opposite direction about two times as far as the previous turn. If the image has improved, turn the ring a little more in the same direction. Repeat this procedure until the image shows the highest quality.
5. Close the aperture diaphragm until optimum contrast is achieved.
6. For examining the same portion of the same specimen again, it is convenient to take a note of the best setting on the correction ring scale. If, however, the different position of the same specimen is observed, repeat the above described procedure starting from step 4.
Note: Note that the image quality will be affected not only by the thickness of the coverglass, but also by the mounting agent used on the specimen and the thickness of the specimen itself.
Micron Optics, 240 Cedar Knolls Road , Cedar Knolls, NJ 07927