What's the difference between these two Canon magnifiers? Canon lens EF 1.4XIII 1.4X third generation multiplier and Canon lens EF 2.

First of all, it is obvious that the magnification of the focal length is different.

Secondly, there is a hidden problem. The higher the focal length magnification, the lower the maximum aperture coefficient.

For example, the maximum aperture of the white rabbit is F2.8, and the aperture is reduced by one level to F4 with the magnification of 1.4.

The aperture of a 2-fold magnifying glass is reduced by 2 levels to F5.6

So you have to weigh the pros and cons.