Originally Posted by guderian93
Not size or wavelength, magnification.
Typically, the highest objective you will encounter on a light microscope is 100x oil.
Theoretically, if you have 20x eyepieces, you could achieve 2000 magnification.
In reality, you begin to lose resolution beyond 1000x magnification on a light microscope. Thus, the standard combination on research light microscopes is 10x eyepieces with a 100x oil objective and a numerical aperture of 1.4.
The law of diminishing returns applies to your question.
Optimal viewing with a light microscope for maximum magnification occurs at 1000x via the use of 10x eyepieces and a 100x oil objective with a 1.4 numerical aperture when used with the proper oil application.
Anything beyond that starts to sacrifice resolution and optical clarity for sheer numbers.
I hope that helps you have a better understanding.