Well, it really doesn't need a PhD in anything but the school of hard knocks. All you have to know is that there is no such thing as a free lunch. Adding a TC is guaranteed by the TANSTAAFL rule to degrade the image.... I disagree that "it's just physics" but my PhD is not in optics...
Glass manufacturing and design is not perfect, each element introduced has defects and aberrations. A TC not only introduces it's own aberrations, but being an enlarger, magnifies existing lens aberrations. The stronger the TC the larger this effect is.I am unaware of an optical principle dictating an IQ loss for a tele-extender.
each element introduced to make a 100-400 has defects and aberrations also...Glass manufacturing and design is not perfect, each element introduced has defects and aberrations. A TC not only introduces it's own aberrations, but being an enlarger, magnifies existing lens aberrations. The stronger the TC the larger this effect is.
This is a well known limitation for any and all TCs. It's why 2x TCs are rarely any good, especially on a zoom. They are only typically used on a very good fast prime to start with.
A 100-400 does not have to operate in two modes, switching the extra elements in and out. The 50-200 is optimised for it's native performance, trading off performance with extra TC elements added. The 100-400 is also optimised for it's native performance, but the 'extra' elements are already in place and optimised for.each element introduced to make a 100-400 has defects and aberrations also...
My gas for the 50-200 was for use with the 1.4TC, but I'm still holding out hope for one of the two lenses on the Olympus roadmap.I suppose it physically fits but the IQ is not up to snuff for them to promote it. Well, there goes any feelings of GAS I had for it.
They don't switch elements in and out. The TC is also stuck by always being the last optical group, in zooms the moving elements aren't limited to being the last group.Sorry but all zooms operate in many modes
Here is a short article by Zeiss on why teleconverters degrade the IQ. Particularly note their suggestion to use them "with a fixed focal length lens except in a “do-or-die” situation."....I disagree that it is "just physics" that might make a 2x extender on a lens not have equal IQ to a lens twice the FL. Think about how a lens is designed.....
Thx, but the IQ con they mention is increasing residual aberrations, and the problem here is greater than that.
Hmm "do-or-die" seems a bit over the top Hasnt there been a lot of people using the old 50-200 oly 4/3 lens with the 1.4 TC? and as I recollect with people be ok happy with the results? but maybe those were do or die situations