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telephoto是什么

Optical Lenses In recent years, the transition from glass to plastic lenses has revolutionized the way we see. In the past, eyeglass lenses were made of glass. However, in recent years, lenses have transitioned to a durable plastic, that is lighter in weight, and less prone to breaking— providing a more comfortable experience.... Learn More Optical Lenses for Children Which optical lenses are best for children? If you are purchasing new eyeglasses for your child, you may not even be aware that different lens options exist. While your optometrist will be able to guide you and recommend a specific type of lens for your child's individual needs, it is a good idea to familiarize yourself with the different lens materials.... Learn More Benefits of Digital Lens Technology Digital lens technology provides custom lenses for a clearer, more natural visual experience. Glasses have been used to help scribes and copyists see better since... Learn More Eyeglass Digital Lenses: FAQs Digital lenses were first created in the early 2000s, and are now readily available for all different types of prescriptions. What if your vision could... Learn More Scratched Lenses: What Can I Do? Scratched lenses aren’t just a bother, they can affect your vision and cause headaches.  Here’s what you need to know about scratched lenses. You may... Learn More Guide to Sunglasses Sunglasses are fashionable, but why are they so important? Most people are aware of the harmful effects ultraviolet (UV) radiation can have on the skin. However, many are unaware that UV radiation can also endanger our ocular health and vision.... Learn More Guide to Bifocals and Multifocals Have you noticed the need to hold your phone, books or restaurant menus farther from your eyes to improve their clarity? Presbyopia is the most common reason most adults begin to wear eyeglasses. The condition generally develops overtime, beginning at around age 40, and is considered a normal part of the aging process.... Learn More Guide to High-Index Lenses High-index lenses are eyeglass lenses that are designed to be thinner and lighter than regular lenses. They are generally recommended for people who have significantly high refractive errors and strong prescriptions for nearsightedness, farsightedness, or astigmatism.... Learn More

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Widelens

The basic concept of a telephoto lens is illustrated by the dialyte lens configuration in which a negative lens is inserted between the objective lens and the image plane. This concept goes back to Kepler, but Peter Barlow developed the idea in the early 1800s by including a negative achromat in telescopes to increase their magnification.

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Our Most Viewed Guide to Optical Lenses Articles Do I Need Reading Glasses? Glass or Plastic: Which Type of Lens Should You Choose? Optical Lenses for Children What Are Transition Lenses? Benefits of Digital Lens Technology What Do Polarized Lenses Do? Scratched Lenses: What Can I Do? Guide to Bifocals and Multifocals

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telephoto lens中文

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Fisheyelens

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Recalling that the image height for a distortionless lens on a flat image surface is \(f\tan\theta\), the reverse telephoto lens has mapping relationships such as \(f\theta\) and \(f\sin\theta\).

An extreme form of the reverse telephoto lens is the fish-eye or sky lens. Such lenses have a total field of view of 180° or more. The image formed by these lenses has very large barrel distortion.

A reverse telephoto lens has a telephoto ratio greater than unity and exhibits a shorter focal length than its overall length, a larger \(bfl\) than is provided by normal lenses of the same \(efl\), lenses with generally large apertures and wide fields of view, and lens elements of physically larger size that allow easier manufacture and handling.

Barrel distortion has the effect of compressing the outer portions of the image towards the central portion, thereby increasing the flux density appropriately.

Telephotolens

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Primelens

After World War II, the Russian designer M. M. Roosinov patented a double-ended reverse-telephoto lens that was nearly symmetrical with large negative lenses surrounding a pair of positive lenses with a central stop. Although the back focal length is quite short, it provides relatively large aperture with a wide field of view and essentially no distortion. Lenses of this type have found significant use in aerial photography and photogrammetry.

Opticallens

A telephoto lens provides an effective focal length \(efl\) that is longer than its overall length \(s_{ol}\) as measured from the front of the lens to the image plane. The telephoto ratio is defined as \(s_{ol}/efl\), thus a lens with a ratio less than one is a telephoto lens.

When the barrel distortion is given by \(f\sin\theta\), the illumination across the image will be constant if such effects as vignetting and stop distortion are absent.

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When most telephoto lenses are used to view objects that are relatively close, the image quality degrades rapidly due to the typical unsymmetrical lens configuration. Some modern telephoto lenses include one or more elements that move as the lens is focused for the purpose of aberration correction.

Barlow type lenses are widely used today. As the telephoto ratio is made smaller, the design of the lens becomes more difficult, primarily due to the Petzval sum increasing.

Circular polarized light occurs when the linear and horizontal components are 1/4 wave out of phase. Elliptical light is what we call all ...

The basic configuration has a large negative lens located in front of a positive objective lens. Since the negative lens makes the object appear closer to the objective lens, the resultant image moves beyond the focal point, thereby making the \(bfl\) greater than the \(efl\).

Theia has three families of lenses using its Linear Optical Technology for correcting barrel distortion. The widest is a 135° field of view model, which has ...