And mathematically, you can express that in terms of how much that object subtends.

从数学 上讲，用该对象对向的程度来表达这一点。

An object is said to subtend a certain angle of your vision based on how close you are to it, and how big it is.

根据 与它的接近程度及它的大小，据说一个物体对着的视野的某个度。

So if you look at our tiny leaf, it may subtend only two degrees of your vision when it’s at your near point – say, 25 centimeters away.

所如果你看着我们的小叶子，当它在你的近点——比如 25 厘米远——时，它能只对着你两度的视线。

But when you look at the leaf through the lens, the virtual image is larger than the actual object, so it subtends six degrees of your vision.

但是当你头看树叶时 ，虚像比实际物体大， 所它对着你的视线六度。

So if you look at our tiny leaf, it may subtend only two degrees of your vision when it's at your near point – say, 25 centimeters away. .

因此，如果看我们的小叶子， 当它在的近点（例如 25 厘米远）时，它能只对着的视线的两度。

In order to find the magnifying power of the lens, you just divide the angle subtended by the virtual image by the angle subtended by your unaided eye.

为了求出片的放大倍率 ，只需用虚 像对除肉眼对。

And the newly subtended angle is the amount that the object subtends when viewed through the eyepiece – the angle between your eye and the rays from the eyepiece.

新的对向是目观察物体时的对向量——你的眼睛与目发出的光线之间的度。

For example, if you’re looking up at the moon, and you cover it with your thumb, then your thumb and the moon are both subtending the same angle to your eye, which we measure in degrees.

例如，如果正在抬头看月亮，并用拇指遮住它，那么的拇指和月亮都会与的眼睛形成相同的度，我们度为单位进行测量。

For example, if you're looking up at the moon, and you cover it with your thumb, then your thumb and the moon are both subtending the same angle to your eye, which we measure in degrees.

例如，如果你抬头看着月亮，然后用拇指遮住它，那么你的拇指和月亮都对着你的眼睛，我们用度数来衡量这个度。