Rationale
Low power objective lens should be used when initially viewing a specimen with a microscope.
When initially viewing a specimen under a microscope, it is always best to start with the lowest magnification to get a broader view of the specimen. This allows you to locate the area of interest and center it in the field of view. As the magnification is low, the depth of focus is also high, which makes it easier to bring the specimen into sharp focus.
A) Oil immersion
The oil immersion lens is not suitable for initial viewing. It provides the highest magnification, typically 100x, and is used to observe details that are not visible with lower power lenses. However, it requires the use of immersion oil to improve the image quality, which can be messy and time-consuming to apply and clean up. Moreover, it has a very narrow depth of focus, which makes it difficult to get a broad view of the specimen and locate the area of interest.
B) Medium power
The medium power lens, typically 10x or 20x, provides a moderate level of magnification. While it can be used after the low power lens to zoom in on the area of interest, it is not the best choice for initial viewing. It provides less field of view and depth of focus than the low power lens, making it harder to locate and focus on the area of interest.
C) High dry
The high dry lens, typically 40x, provides high magnification without the need for oil. Like the medium power lens, it can be used after the low power lens to examine the specimen in greater detail. However, it has an even narrower field of view and depth of focus than the medium power lens, making it unsuitable for initial viewing.
D) Low power
The low power lens, typically 4x or 10x, provides the lowest magnification. It offers the widest field of view and the greatest depth of focus, making it the ideal choice for initial viewing. It allows you to quickly and easily locate and focus on the area of interest, which can then be examined in greater detail with higher power lenses.
Conclusion
When initially viewing a specimen with a microscope, it is best to start with the low power objective lens. It provides a broad view and a high depth of focus, which allows you to easily locate and center the area of interest. Once the area of interest is located and centered, you can switch to higher power lenses to examine it in greater detail. This methodical approach simplifies the process of viewing a specimen under a microscope and helps to prevent damage to the microscope and the specimen.
