Our optics101 now came to the last physical part, the eyepiece.
About the eyepiece, it is what you know [10x] 50.
The eyepiece usually consists of more than 2 lenses to achieve for magnifying the object, it is the last trip of the light before going into your eyes. Most of people assume that the magnification is related to the objective lens, in terms of ultimate magnification alone, this is true. But to binoculars, it is the eyepiece that determines the magnification.
As always said the magnification is not the larger the better. On the one hand, subject to the limit of the Objective lens ultimate magnification, the other hand, as the magnification increases, the exit pupil will become smaller and smaller. This has already been mentioned in the objective lens.
Another point never mentioned is the aberrations, either by squeezing or stretching, this usually happens with very poorly produced binoculars, especially like 10-20x zoom binoculars.
At the same time, the picture shows another problem. This is another function of the eyepiece, the elimination of chromatic aberration and dispersion. A binocular that does not reduce chromatic aberration will form a distinct bright edge (usually purple or blue) around the edge of the object and the entire field of view will be off-color (usually yellowish or greenish) from the real one, while a telescope that controls it effectively will be less noticeable. Yes, chromatic aberration and dispersion cannot be avoided, they can only be reduced. So chromatic aberration and dispersion are the most intuitive factors that affect our use of binoculars.
The good thing is, by adding a piece of ED glass, chromatic aberration and dispersion can be corrected to an acceptable range for the human eye, if we do not pay attention on it.
Internet & Photo by Edi Libedinsky on Unsplash