[Klaus]

Greetings to all, this is my first post. I have been using the XF 16-80mm f4 for 2 months, it was in kit with the X-T3, all seasoned with a good cashback. Probably not having spent too much on his purchase makes me more benevolent and less critical towards this lens. Like everyone else, I also started photographing walls and bookcases to find out how many lines per cm I got, then I went out to photograph the world and I find this lens absolutely splendid and perfect for its purpose. It is well built, the AF is instantaneous, WR and OIS work very well and the resolution is fine from corner to corner with a tip of excellence in the center of the image. When they say that its 3D performance is better than 2D it is true. Probably f5.6 is the best aperture but F4 is already workable. When I was a child, my teacher said that apples should be added to apples, it is useless to make comparisons with lenses that have other purposes. I did a comparison test with the Pentax HD DA 16-85mm f3.5-5.6, a lens that everyone considers excellent, and I can say that the images are practically superimposable. I apologize for my poor English and I hope the concepts have been understood ...

Sounds like field curvature which is less relevant in real-world than on walls.