It was a general comment just to prevent a repetition of the mentioned topic where the focal length FX vs DX "equivalence" is beaten to death
Agreed; it's easy to digress.
Would be nice if we can keep this topic clean and on topic as it contains valuable information of the TC-20E III as you mention.
Agreed;
I did my homework and wanted to share the results.
It appears many members
were surprised at the results ... which exceeded even my own expectations.
Optimal results
are dependent upon using
the right lens +
the right aperture, etc.
So I felt this was valuable info to share.
Personally I was a big fan of the 1.7TC, better IQ than the 2.0, half a stop faster and almost the same extra reach.
The 1.4x TC III has better IQ than the 1.7 TC III ... but "not enough" reach to be valuable, IMO (630mm on the D500 compared to 765mm)
The 1.7x TC III has better IQ than the 2x TC III ... and, as you say, "almost" the reach of the 2x TC (765mm on the D500 compared to 900mm).
Each step up gives an extra 135mm of reach ...
My point here is, if used correctly, and on
the right lenses, at
the right aperture, the 2x TC III is
plenty sharp ... and gives
the best reach of the bunch.
Reading some of the reviews, I almost didn't buy the 2x TC III ... however, in
reading carefully, I realized
you need the right lens to use with the 2x (which I had) and I decided to go ahead and get it.
You also need to use the right aperture.
I would rather use my D810 + 2x TC (600mm) than use a D500 + 1.4x TC (630mm).
With the D500, I would rather have
the extra 135mm (with a
2x TC) than lose that same 135mm of reach (with a
1.7x TC).
While there may be a negligible difference in IQ, and a stop of light with the 2X TC, this is offset by the high ISO capability of the D500 ... and the extra 135mm of reach surely does come in handy not to mention an extra 270mm over the 1.4x TC
Jack