Having three focal lengths.
三焦距的有三个焦距的
Eyeglasses having trifocal lenses.
有三焦距镜片的眼镜
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 image is out of focus.
这影像的焦距没调好。
Don't forget to focus the lens.
别忘了调节镜头的焦距。
best image plane of zoom lens
变焦距物镜的最佳像面
focusing glass [ screen ]
【摄】调焦距用的毛玻璃
There are three types of focusing - guesstimate, rangefinder and autofocus .
有三种对焦方式-猜估，用测距仪及自动对焦。
There're three types of focusing guesstimate, rangefinder and autofocus.
有三种对焦方式——猜估，用测距仪及自动对焦。
There are three types of focus- guesstimate, rangefinder and autofocus.
有三种对焦方式??猜估，用测距仪及自动对焦。
For that I want only your face to be in-focus, and the rest of the picture will be out-of-focus.
我只使你的脸在焦距内，其它的在焦距外，
Performance Analysis of the Elliptic Beam Ring-focus Antenna with a Variable Focal Distance
椭圆波束变焦距环焦天线的性能分析
back focal distance
【光】后焦距﹝指镜头与菲林间的距离﹞
equivalent focal length
当量焦距，等效焦距
Focus-to-film distance(f.f.d)
焦点-胶片距离(焦距)
The flatter the ellipse, the farther apart are the foci, and the farther each focus is from the center .
椭圆越扁平，两焦点之间的距离越远，每个焦点离中心的距离也越远。
Focus your camera (on those trees).
把照相机的焦距调准（把焦点集中在树上）.
Discussion about Off-Focus Influence on MTF for Long Focus Aerial Camera
长焦距航天遥感相机离焦对传递函数的影响