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The eye relief of an optical instrument (such as a telescope, a microscope, or binoculars) is the distance from the last surface of an eyepiece within which the user's eye can obtain the full viewing angle. If a viewer's eye is outside this distance, a reduced field of view will be obtained.
Generally, an eye relief over 16 mm should be adequate for any eyeglass wearer. However, if glasses frames are thicker and so significantly protrude from the face, an eye relief over 17 mm should be considered. Eyeglasses wearers should also look for binoculars with twist-up eye cups that ideally have multiple settings, so they can be partially ...
The short eye relief is more critical in short focal lengths below about 10 mm, when viewing can become uncomfortable – especially for people wearing glasses. The Plössl eyepiece was an obscure design until the 1980s when astronomical equipment manufacturers started selling redesigned versions of it. [ 7 ]
Eye relief – Eye relief is the distance from the rear eyepiece lens to the exit pupil or eye point. [15] It is the optimal distance the observer must position their eye behind the eyepiece to see a non-vignetted image. The longer the focal length of the eyepiece, the greater the eye relief.
Bioptics, also known as a bioptic in the singular, and sometimes more formally termed a bioptic telescope, is a term for a pair of vision-enhancement lenses. They magnify between two and six times, and are used to improve distance vision for those with severely impaired eyesight, especially those with albinism .
The first of these was the Hamiltonian telescope patented by W. F. Hamilton in 1814. The Schupmann medial telescope designed by German optician Ludwig Schupmann near the end of the 19th century placed the catadioptric mirror beyond the focus of the refractor primary and added a third correcting/focusing lens to the system.
To avoid damage to your eyes, you can only view an eclipse safely through specially designed solar viewing glasses — i.e. "eclipse glasses" — or using a safe handheld solar viewer at all times.
The Large Binocular Telescope at the Mount Graham International Observatory in Arizona uses two curved mirrors to gather light. An optical telescope gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through electronic image sensors.