CyberDyneSystems wrote in post #17339456
A quick note on the 1.4x with this lens.There were shots I was looking at in C1 and I was mystified how the aperture had gotten turned up to f/8-f/9 when my goal had been to shoot with it wide open. The images themselves displayed no tell tell signs of any noticeable difference in Image quality. finally it dawned on me, "Oh yeah, that's when I had the 1.4x (MKII) on. I always stop down at lease one notch with a T-Con, thus f/9.
A lot of that has to do with the size of your pixels ... on a 7D2 or 70D the difference should be more obvious, not that this is a bad thing. I have a 3.1MP D30 that I bought used for $140 just for the novelty of the big pixels - other than global contrast dropping a little, there is little loss in pixel contrast even with 2x.
On the old 100-400mm the addition of a 1.4x even on a 1D meant focus went out the window, and IQ went down noticeably.
I used a 2xIII and manual focus with my 100-400 vI at f/18 on my 18MP 7D; I didn't find it to be all that bad, but my goal is subject quality, not pixel quality or full image quality. While it is sometimes hard to believe that there is more detail looking at the 2x image at 100% pixel view, when you actually scale both to the same subject size, the detail is greater with the 2x (with the same shutter speed, physical aperture size at the sweet spot, and 4x the ISO), and the size of the radius of the AA filter is half the size in the result. AA filters create a bigger usefulness for TCs, as it makes it easier to get around them when they aren't necessary.
