focal-length

基本解释

At present, some difficulties are encountered in measurement of long focal-length of mirrors.
目前，大口逕長焦距反射鏡焦距的精確測量存在很大難題。
One zoom lens can replace several fixed focal-length lensed, but results are likely to be inferior.
一個變焦鏡頭可以代替多個固定焦矩鏡頭，但傚果很可能比不上。
Using a group of mirrors and a housing that's almost big enough to use as a coffin, Canon was able to stretch the focal-length on this SLR-specific lens to 5,150mm.
佳能的這款單反相機專用折反鏡頭採用了一組折反鏡片，以及一個跟棺材差不多大的鏡身，其焦距被拓展到5150mm。

Featuring a powerful high-magnification optical 26X super-telephoto zoom lens, the new PENTAX X-5 provides photographers with a focal length of 4mm-104mm (22.3mm ultra-wide angle to 580mm super telephoto 35mm equivalent).
ENGADGET: Pentax intros X-5 superzoom camera with 26x lens, tiltable LCD
The high-end Schneider lens offers a 24mm, ultra-wide focal length and 3x optical zoom.
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TL34HD boasts an impressive resolution of 14.7 megapixels and renowned Schneider lens yielding a 28mm wide-angle focal length with 3.6x optical zoom.
ENGADGET: Samsung gets official with 14.7MP TL34HD point-and-shoot

the distance from the focal point of a lens or mirror to the reflecting surface of the mirror or the centre point of the lens

焦距
A new method of measuring telephoto lens focal length is presented in this paper.
提出一種新的測量長焦透鏡焦距的方法。
焦長度
焦長

焦距
Using Gradual Aberration optimization Method, a 6m focal length, 600mm aperture off-axis aspherical optical system is successfully aligned.
採用像差逐項優化法,成功地裝調了焦距爲6m 口逕600 mm 的離軸三反鏡光學系統。
焦點距離
焦