American Society for Clinical Pathology (ASCP) Technologist in Cytogenetics certification (ASCP CG) Practice Test

What is the optimal objective lens for capturing chromosome images?

1. Apochromatic

2. Planapochromatic

3. Monochromatic

4. Diphasic

The correct answer is: Planapochromatic

The optimal objective lens for capturing chromosome images is the planapochromatic lens. This type of lens is designed to provide excellent color correction and flatness of field across the entire image, which is crucial when observing the fine details of chromosome structure. In cytogenetics, where the accurate visualization of chromosomes is essential for proper analysis and identification, planapochromatic lenses can produce images that retain clarity and precision, even at higher magnifications. Planapochromatic lenses significantly reduce chromatic aberration, thereby ensuring that different colors of light are focused on the same plane, which is vital for distinguishing between closely located chromosomes or chromosomal regions. Furthermore, these lenses allow for better resolution and contrast, making them ideal for viewing the delicate features of chromosomes. While apochromatic lenses also provide good color correction, they may not offer the same level of field flatness as their planapochromatic counterparts. Monochromatic lenses do not offer the necessary corrections for chromatic aberrations and are not suitable for capturing the comprehensive details needed in chromosome imaging. Diphasic units are designed primarily for phase contrast microscopy but do not specifically enhance image capture for chromosomal analysis. Therefore, planapochromatic lenses stand out as the superior choice for this specific application.