Focal distance length的意思|示意

Focal length: The distance between the centre of a lens and its principal focus.

焦距：镜头中心与其主焦点的距离。

The influences of pump energy, focal length and distance between fiber and lens on SBS reflectivity and waveform in multimode fiber are investigated theoretically and experimentally.

从理论和实验上研究了不同焦距下泵浦能量以及透镜与光纤间距对多模光纤中的SBS能量反射率和脉冲波形的影响。

The first shot was taken with a short focal length (around 70mm) and from a relatively close distance and the background looked quite far away and small.

第一张焦距约70 mm，在相对近的距离拍摄，背景看起来很远而且很小。

Once you choose a lens whose focal length is closest to the focal length required by your imaging system, you need to adjust the working distance to get object under inspection in focus.

一旦你选择一个镜头其焦距是最接近于你成像系统所需之焦距，你需要调较工作距离去获取观察目标物的焦点。

If you know the FOV, sensor size, and working distance, you can compute the focal length of the lens you need using the following formula.

如果你知道视野FOV，感应器大小，和工作距离，你能用以下之方程序去计算你所需之镜头的焦距。

Using a longer focal length and photographing stars far from the north star increase the distance stars will move across the image.

使用长焦镜头拍摄远离北极星的星星，会增加星星在相片上移动轨迹。