Ud

RO: Ud - ultra low dispersion EN: Ud glass lenses

Fotografie

Lenses made from fluorite are extremely expensive due to the high cost of synthetic fluorite crystal production. UD (ultra low dispersion) glass made an appearance in the latter half of the 1970s, delivering a special optical glass which could provide characteristics similar to fluorite but at a lower cost and thereby answering another desire of lens designers. While the index of refraction and dispersion of UD glass are not as low as fluorite, they are significantly lower than other types of optical glass. Moreover, UD glass does display similar partial dispersion characteristics. The selection of the proper lens element combination in consideration of the intended focal length and other factors can provide close to the same effect as fluorite, (two UD lens elements are equivalent to one fluorite element). Super UD glass was introduced in 1993 as a new material that achieves almost the same performance as fluorite while achieving a new balance of cost reduction and higher quality.
Canon glossary EU

96%

Accuracy

Ud

Ultra Low dispersion lens, pls refer to ED, LD sections.

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85%

Accuracy

Ud - ultra low dispersion

Vezi Apocromat. .

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86%

Accuracy

Ud - ultra low dispersion

Vezi Apocromat.

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