Definition. A tumor is an abnormal growth caused by the uncontrolled division of cells. Benign tumors do not have the potential to spread to other parts of the body (a process called metastasis) and are curable by surgical removal.
Fine Focus: This is the knob used to fine tune the focus on the specimen. It is also used to focus on various parts of the specimen. Generally one uses the coarse focus first to get close then moves to the fine focus knob for fine tuning. Field of View: Sometimes abbreviated FOV, it is the diameter of the circle of light that you see when looking into a microscope.
A zoom lens is a mechanical assembly of lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed focal length (FFL) lens (see prime lens).A true zoom lens, also called a parfocal lens, is one that maintains focus when its focal length changes.A lens that loses focus during zooming is more properly called a varifocal lens.enses in the latter group of zoom lenses, sometimes referred to as normal zooms, have displaced the fixed focal length lens as the popular one-lens selection on many contemporary cameras. The markings on these lenses usually say W and T for Wide and Telephoto.