Microscope magnification is used by rotating the nosepiece to select a higher power objective lens, typically one objective at a time and using the focus knobs to achieve a clear image at the new magnification.
Here's a more detailed breakdown of how to effectively use microscope magnification:
1. Initial Setup and Low Power Observation:
- Start with the lowest power objective lens (e.g., 4x or 10x). This provides the widest field of view, making it easier to locate the specimen.
- Place your prepared slide on the microscope stage and secure it with the stage clips.
- Using the coarse and fine focus knobs, bring the specimen into focus. Coarse focus is for large adjustments, while fine focus is for precise tuning.
2. Increasing Magnification:
- Rotate the Nosepiece: Carefully rotate the revolving nosepiece to the next higher power objective lens (e.g., from 10x to 40x). Make sure the objective lens clicks into place.
- Refocus: After switching to a higher power, you will almost certainly need to refocus. Start with the fine focus knob. Avoid using the coarse focus knob at higher magnifications, as it can easily move the objective too close to the slide, potentially damaging both.
- Adjust Light: Increasing magnification often requires adjusting the light intensity. The light source or diaphragm can be used to control the amount of light passing through the specimen. Too little or too much light can obscure details.
3. Understanding Magnification Power:
- Objective Lens Magnification: Each objective lens has a specific magnification power (e.g., 4x, 10x, 40x, 100x).
- Eyepiece Magnification: The eyepiece (ocular lens) also has a magnification power, typically 10x.
- Total Magnification: To calculate the total magnification, multiply the objective lens magnification by the eyepiece magnification. For example, a 40x objective lens used with a 10x eyepiece provides a total magnification of 400x.
4. Important Considerations:
- Working Distance: As magnification increases, the working distance (the distance between the objective lens and the slide) decreases. Be very careful when using high-power objectives (especially 100x) to avoid crashing the lens into the slide.
- Resolution: Magnification alone is not enough. Resolution, the ability to distinguish between two closely spaced objects, is also critical. Higher magnification without sufficient resolution will result in a blurry image.
- Oil Immersion: The highest power objective lens (100x) typically requires oil immersion. A drop of special immersion oil is placed between the objective lens and the slide to improve resolution. Use only immersion oil specifically designed for microscopy.
- Step-by-step Approach: It's good practice to increase magnification gradually, one objective at a time. Skipping directly to a high-power objective makes it more difficult to find and focus on the area of interest.
In summary, using microscope magnification effectively involves selecting the appropriate objective lens, carefully focusing, adjusting the light, and understanding the relationship between magnification, resolution, and working distance.
