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Zoom lenses (sometimes referred to as "true" zoom) are ideally parfocal, in that focus is maintained as the lens is zoomed (i.e., focal length and magnification changed), which is convenient and has the advantage of allowing more accurate focusing at maximal focal length then zooming back to a shorter focal length to compose the image. [1]
Cone of light behind an achromatic doublet objective lens (A) without (red) and with (green) a Barlow lens optical element (B). The Barlow lens, named after Peter Barlow, is a diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components that are after it in the system.
The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century.
Many so-called "zoom" lenses, particularly in the case of fixed-lens cameras, are actually varifocal lenses, which gives lens designers more flexibility in optical design trade-offs (focal length range, maximal aperture, size, weight, cost) than true parfocal zoom, and which is practical because of autofocus, and because the camera processor ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 13 November 2024. Portable Document Format, a digital file format For other uses, see PDF (disambiguation). Portable Document Format Adobe PDF icon Filename extension.pdf Internet media type application/pdf, application/x-pdf application/x-bzpdf application/x-gzpdf Type code PDF (including a single ...
an Office suite; allows to export (and import, with accuracy limitations) PDF files. Microsoft Word 2013: Proprietary: Desktop software. The 2013 edition of Office allows PDF files to be converted into a format that can be edited. Nitro PDF Reader: Trialware: Text highlighting, draw lines and measure distances in PDF files. Nitro PDF Pro ...
Two Leica oil immersion microscope objective lenses; left 100×, right 40×. The objective lens of a microscope is the one at the bottom near the sample. At its simplest, it is a very high-powered magnifying glass, with very short focal length. This is brought very close to the specimen being examined so that the light from the specimen comes ...
Antonie van Leeuwenhoek (1632–1723). The field of microscopy (optical microscopy) dates back to at least the 17th-century.Earlier microscopes, single lens magnifying glasses with limited magnification, date at least as far back as the wide spread use of lenses in eyeglasses in the 13th century [2] but more advanced compound microscopes first appeared in Europe around 1620 [3] [4] The ...