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

从数学 上讲，您可以用该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.

根据您 与它的接近程度以及它的大小，据说一个体着您的视野的某个度。

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.

所以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，它可能只着你两度的视线。

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.

是当你通过镜头看树叶时 ，虚像比实际体大， 所以它着你的视线六度。

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，如果您看我们的小叶子， 当它在您的近点（例如 25 厘米远）时，它可能只着您的视线的两度。

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.

为了求出镜片的放大倍率 ，只需用虚 像除以肉眼。

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.

新的是通过目镜观察体时的量——你的眼睛与目镜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，如果您正在抬头看月亮，并用拇指遮住它，那么您的拇指和月亮都会与您的眼睛形成相同的度，我们以度为单位进行测量。

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着你的眼睛，我们用度数来衡量这个度。