Optical microscope used at the Wiki Science Competition 2017 in Thailand
Several objective lenses on a microscope.
18th-century microscopes from the Musée des Arts et Métiers, Paris
Objective lenses of binoculars
Carl Zeiss binocular compound microscope, 1914
Two Leica oil immersion microscope objective lenses; left 100×, right 40×.
Electron microscope constructed by Ernst Ruska in 1933
Camera photographic objective, focal length 50 mm, aperture 1:1.4
Fluorescence microscope with the filter cube turret above the objective lenses, coupled with a camera.
The segmented hexagonal objective mirror of the Keck 2 Telescope
Types of microscopes illustrated by the principles of their beam paths
Evolution of spatial resolution achieved with optical, transmission (TEM) and aberration-corrected electron microscopes (ACTEM).
Unstained cells viewed by typical brightfield (left) compared to phase-contrast microscopy (right).
Modern transmission electron microscope
Transmission electron micrograph of a dividing cell undergoing cytokinesis
Leaf surface viewed by a scanning electron microscope.
First atomic force microscope

They are used in microscopes, binoculars, telescopes, cameras, slide projectors, CD players and many other optical instruments.

- Objective (optics)

The earliest known examples of compound microscopes, which combine an objective lens near the specimen with an eyepiece to view a real image, appeared in Europe around 1620.

- Microscope
Optical microscope used at the Wiki Science Competition 2017 in Thailand

1 related topic

Alpha

A collection of different types of eyepieces.

Eyepiece

A collection of different types of eyepieces.
A 25 mm Kellner eyepiece
Simulation of views through a telescope using different eyepieces. The center image uses an eyepiece of the same focal length as the one on the left, but has a wider apparent field of view giving a larger image that shows more area. The image on the right has the same apparent field of view as the center eyepiece but has a shorter focal length, giving the same true field of view as the left image but at higher magnification.
The Plössl, an eyepiece with a large apparent field of view
Examples (from left to right) of 2" (51 mm), 1.25" (32 mm), and 0.965" (24.5 mm) eyepieces.
The eye relief. 1 Real image 2 - Field diaphragm 3 - Eye relief 4 - Exit pupil
Negative lens
Convex lens
Huygens eyepiece diagram
Ramsden eyepiece diagram
Kellner eyepiece diagram
Plössl eyepiece diagram
Orthoscopic eyepiece diagram
Monocentric eyepiece diagram
Erfle eyepiece diagram
König eyepiece diagram
RKE eyepiece diagram
Nagler type 2 eyepiece diagram
Nagler type eyepieces

An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as telescopes and microscopes.

The objective lens or mirror collects light and brings it to focus creating an image.