The Ducks Guts from the coal face bedroom test and more Lol
1) hold up the TC II side by side with TC III and look through from the direction of the camera mount side, you will see clearly that the the TC II has ever such a slightly larger view and the subject appears literally closer or magnified more, do this on a subject like a tree of plant from 6 or 7 meters. You will also see that there is a slight difference between the whole diameter be it an optical illusion or not, also there is eer so slighylynoticble a bit of distrotion in the outer edges of teh II, is this a sample vairation or anothe reason for teh redesigne ?, i handed this test over to several friends without telling them what they will see , all picked it clearly, validating that i haven't lost it ...yet LOl.
2) then hold the two TCs tightly side by side under a single LED bedroom ceiling light around waist height, you will see flair in both TCs as you move them around up or down, OK if you made it this far you will then be slapped in the face with a strong colour cast from the TC II again spotted by the friends with out being prompted.
3) Hold up both TCs next to each other from the direction of the camera mount, look outside through a widow, you will see clearly that the TC II is slightly brighter or looks more like plain glass or has a little glare about it as where the TC III looks like it has a very fine polarized look or filtered about it showing slightly nicer contrast and colour, it looks far better than the the TC II.
4) The TC III has a different formulae, added coating, the optical clarity by viewing through them hand held is clearly apparent in different and challenging conditions like snow or white surf.
5) Comparing the images on the back of the D850 screen at 100% its hard to pick the difference as far as needle sharpness goes, look at the images on an Eizo screen with a super high end Mac Pro Tower and there is a difference in micro contrast, glare and colour, in doors under articial lights like a staium you may see that colour cast deponding on where your are positioned......... of course we then take these high end photos taken on exotic gear only to email them via your phone via some crappy telco LOL.
6) Before buying a TC III i asked Thom hogan if it was a worth while upgrade, he answered defiantly. I never asked why, Now when i trolled the internet and looked at reviews till my head hurts i found the majority of reviewers say the upgrade from the II to the III is not worth it as they can hardly notice any difference if at all, and to the average majority of people i would see why that's the case and would agree their isn't a lot in it looking at things initially, however as i ignore mostly the internet reviews and ask why did Nikon upgrade the TC II led me to do the coal face test of my own as mentioned in point 1, 2, 3, also the TC x 2 II was a pig, the TC x2 III is better, it would be logical that similar issues with TC x 2 II would be in the TC 1.4 II but far less evident being only 1.4, so their had to be a difference and for me there clearly is.
Once seen or noticed, or using specific different lenses like the PF or FL lenses, different conditions low light high iso, contrasting conditions, artificial lighting, as time goes on its in there the difference become noticeable more so in some conditions than others.
To me the magnification difference in my point 1 has me puzzled. asking was the TC 1.4 II a 1.5 or 6 not a true 1.4 ??
Any way i upgraded for only $200 AUD difference as the II has a good resale because everyone thinks their isn't a difference to the III.
The D850 on good glass shows a difference.
Only an opinion
Oz down under