Question

When you are focusing an object under the microscope, explain why some parts are in focus and some parts are out of focus?

Answer 1

Some parts of an object may be in and out of focus under a microscope due to differences in specimen depth and because high magnification lenses require precise focusing. Objective lenses are parfocal, aiding in maintaining focus when switching magnifications, and the eyepiece further magnifies the image to create a clear view for the observer.

Step-by-step explanation:

When you are focusing an object under the microscope, some parts may be in focus while others are out of focus because of differences in depth within the specimen, which is being magnified by the microscope's lenses. The first lens, the objective lens, typically has magnification values from 5x to 100x and is mounted to be parfocal, meaning it keeps the specimen nearly in focus when switching between magnifications. The second lens, the eyepiece or ocular, contains several lenses and works with the objective lens to magnify the object further.

When viewing the specimen, the field of view is limited and dependent on the combination of eyepiece and objective lens used. As the objective lens magnifies the object, the working distance between the lens and the specimen decreases. High magnification lenses require fine adjustments to the focus, using the fine focus knob, to bring a very small and specific area of the specimen into focus.

Lenses focus light at an image point by bending the light waves that pass through them. The focal length of a lens is the distance over which these rays are refracted to a single point, and it can be affected by factors such as lens curvature, the refractive index of the lens material, and the wavelength of the incoming light.

Answer 2

Your basic lens is the pinhole camera. You can illustrate a picture to exemplify how the light rays bypass through the hole to outline a picture on the screen. A lens is a development on the pinhole, but the pinhole result is still there, defined by the width of the lens. In a camera, the width is adjustable and that is what the f-stop embodies. A small f-stop means a small hole and the pinhole effect permits focus in a large range. A large f-stop means the focus has to be more accurate, and things in front or behind the focus point are blurred. In a microscope you have no such adjustment, so depth of focus is always the same meaning that some objects in front of and behind the object being viewed will also come into view in focus.