With the lower focal points all in the same plane; -- said of sets of eyepieces so mounted that they may be interchanged without varying the focus of the instrument (as a microscope or telescope) with which they are used.
A lens design such that allows specimens to remain focused at different magnification powers.
a term used describing the property of a microscope where the subject stays in focus when the objective lenses are changed. Less then 1/2 of a revolution from the fine adjustment is usually acceptable.
Commonly refers to a group of eyepieces that can be swapped without refocusing. Some makers produces sets of eyepieces that are designed to be parfocal.
A parfocal eyepiece is one designed to allow a change of eyepieces without refocusing the telescope.
Refers to a group of eyepieces by a manufacturer which requires little or no focusing between eyepieces.
A lens design such that specimens that appear in focus at one magnification will also appear focused when the magnification level is changed. Keep in mind, however, that depth of field (how much of a specimen's height will appear in focus at one time) changes significantly when magnification is changed. The higher the magnification, the shallower the depth of field. See also: parcentered BACK
A set of eyepieces (e.g: astronomical) or objectives (e.g: in a microscope) the focus and image sharpness of which is the same as they are swapped around.
feature of microscope which allows rotation of lenses with only minor focus movement, lenses alignment
This is a focus issue. When changing from one objective to another, the new image should be either in focus or close enough so that you can refocus with only minor adjustments. Most microscopes are parfocal.
The specimen remains in focus when switching between objectives.
A method of setting up the microscope in order to have similar focal distances for objectives of different magnifications.
A group of eyepieces whose focal points in the focal plane is the same so that when exchanging eyepiece re-focusing would not be required.