How to choose lens and fluorite lens characteristics

by:Crylight     2021-05-25

When choosing lenses, you must first understand your own needs and preferences. Depending on your occupation, activities you often engage in or travel requirements, etc., depending on factors such as frequent outdoor activities or travel, color-changing lenses are a good choice.

   When the nature of work or living habits is prone to dust and scratches on the lens, it is best to choose glass lenses instead of super-hard lenses. Often speaking in public or in front of the lens It is best to choose anti-reflective coated lenses to increase the trust of others, and it is best to choose anti-radiation lenses for workers who often look at computer screens.

   If the lenses that have been used before are easily scratched, in addition to the habit of cleaning the glasses, the durability and scratch resistance of the glass lenses are very prominent. In addition, if If you are not satisfied with the thickness or appearance of the lens, you may choose ultra-thin or aspherical lenses.

   As for the selection principle of lens color, the color of the lens is generally white (no color) because the white lens has a perspective rate of 98.5%. The optical lens can hardly feel the existence of the lens. However, based on the climate considerations in the subtropical Taiwan region, and in terms of consumers' personal aesthetics, colored lenses can attract consumers' attention.

   Colored lenses can be divided into two types: full color and gradient color, but the gradient lens similar to ordinary sunglasses is better, and the color is tea, light Violet sky blue and other colors are suitable. If you choose full-color lenses, dark green, ink gray, ink tea and other colors are better. It is worth noting that if you wear colored lenses for a long time, you will feel afraid of light when not wearing them. Try not to use it at night. Therefore, when consumers choose colored lenses, in addition to considering their personal needs, they should also refer to the opinions of professionals.

   For people over 45 years old, it is more convenient to use distance and near lenses.

   After the age of 40, many people will become presbyopic. Reading newspapers and magazines up close is very ugly, so you must wear presbyopic glasses. Presbyopia can be seen with optical lenses. Bifocal lenses that are convenient for viewing near and far, and progressive multifocal lenses with no boundaries, etc. It is worth noting that the selection of glasses must be explained by professionals.

How to choose within 300 degrees?

   If the visual acuity is within 300 degrees, you can choose a lens with a refractive index of about 1.5. Because the degree itself is not deep, if the frame is suitable, the lens is not thick, and the weight is relatively light;

   How to choose about 300-500 degrees?

   With a visual acuity of about 300-500, you can choose a lens with a refractive index of 1.56-1.59, because it tends to be more consistent in terms of cost performance, appearance and feeling;

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How to choose    above 500 degrees?

   Opticians with a visual acuity above 500 degrees are best to choose lenses with a refractive index above 1.60. For high depth numbers, the higher the refractive index of the matched lenses , The thickness of the lens will be thinner, and the weight will be relatively lighter. Focusing lens

   fluorite lens, that is, a lens made of fluorite, the earliest fluorite lens, successfully developed by Canon in Japan in 1960, used for photographic lenses Manufacturing. Since ordinary optical lenses are difficult to compensate for the bending aberration of the picture, the length of the long-focus telephoto lens cannot be shortened. However, by using low-refractive fluorite lenses, the length of the telephoto lens can be greatly shortened while maintaining high image quality.

   Fluorite lens is made of fluorite, which is a magical stone that emits light at high temperatures. It is named 'fluorite' because it has the same beautiful color as fireflies flying in the summer night.

   The earliest fluorite lens was successfully developed by Canon in 1960 and used for the manufacture of photographic lenses. However, pure large fluorite rarely exists in nature, and its physical properties (low hardness, easy to scratch) make it difficult to process, which makes the lens with aspherical fluorite lens extremely expensive and precious.

   Canon in the late 1970s, based on the original fluorite lens manufacturing technology, further developed another alternative to optical glass mixed with patented oxides. Named the ultra-low dispersion lens (UD-UltraDispersion), this is a lens close to the optical characteristics of fluorite lens, but the manufacturing cost is greatly reduced.

   After that, Canon developed a more advanced (SuperUD) lens in 1990. Generally speaking, two ultra-low dispersion lenses are equivalent to the imaging effect of a fluorite lens. , And a SuperUD lens can provide the same performance as a fluorite lens. The lens made of these two kinds of lenses has strong anti-dispersion ability, and the chromatic aberration is very small, which can significantly improve the image definition, especially when used in a telephoto lens. This kind of lens is in the Canon lens group. widely used.

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