08-23-2016, 11:45 AM
You are aware that you are a bit nit-picky there. 
Especially considering the fact that nobody knows whether the f/4 lens is actually really f/4 and not f/3.8 or f/4.2 nor whether the focal lengths are correct (which they never are really).
Regarding the lens examples you will always be able to come up with an exception to the rule because of some special design aspect.
The whole point is that there isn't really a difference when considering the grand concept - plus/minus. Nobody will notice a 10-15% difference in the real life anyway. It just doesn't matter.
Especially considering the fact that nobody knows whether the f/4 lens is actually really f/4 and not f/3.8 or f/4.2 nor whether the focal lengths are correct (which they never are really).
Regarding the lens examples you will always be able to come up with an exception to the rule because of some special design aspect.
The whole point is that there isn't really a difference when considering the grand concept - plus/minus. Nobody will notice a 10-15% difference in the real life anyway. It just doesn't matter.