The ratio ? / ? is called the angular magnification.
2.
:A simple lens doesn't have a single angular magnification.
3.
Magnifying glasses are a special case : these are commonly quoted as having a particular angular magnification.
4.
In this case the angular magnification is independent from the distance kept between the eye and the magnifying glass.
5.
The total angular magnification of a microscope image is then simply calculated by multiplying the eyepiece power by the objective power.
6.
In doing so, the overall angular magnification of the system varies, changing the effective focal length of the complete zoom lens.
7.
Historically, Abbe described microscope eyepieces differently, in terms of angular magnification of the eyepiece and'initial magnification'of the objective.
8.
But the " angular magnification " is 5, meaning that the object appears 5 times larger to the eye than without the lens.
9.
This definition of lens power relies upon an arbitrary decision to split the angular magnification of the instrument into separate factors for the eyepiece and the objective.
10.
If instead the lens is held very close to the eye and the object is placed closer to the lens than its focal point so that the observer focuses on the near point, a larger angular magnification can be obtained, approaching
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