I agree very nice image.
As to the best back from Phase One1, I really can't agree. I feel the image quality, DR, shadow recovery, high recovery etc, is pretty much identical to the IQ3. At first I thought the IQ4 at 50 ISO and the extra quality 16 bit raw was giving me a bit more shadow recovery, but I now it seems about the same tested it again this morning. Actually by 200 ISO, shadow push in low light is very limited for me. And by 400, pretty much too much noise. For the first time I do see issues with Rolling shutter in high quality 16 bit and normal 16 bit, not as common in 14 bit. I used the ES on the IQ3 almost 100% of the time, and really never saw movement induced rolling shutter issues, however I am seeing them in trees branches, and grasses, at times.
I can't figure out why the chip with BIS gives to much life to tech camera glass, but seems not to give much in overall shadow recovery with the XF and various Blue ring lenses, 35mm, 40-80 etc.
On the flip, you can easily use the Schneider 35mm XL with CF and no LCC is really needed as long as you don't shift any. This lens being symmetrical is just wonderful for stitched panos. The difference between the IQ3 and the 35XL and IQ4 is really amazing. And you can take the center filter off and still get a good image. This morning with the CF I shot all morning and never needed a LCC.
Firmware is really behind on where it should be. And new issues seem to keep coming up at least for me.
I have issues with image playback (images have a line through them, and 1/2 of image is too dark when zoomed to 100%
Auto Live View seems to pulse brightness settings making it hard to use
Power share seems not to work like it did on the IQ3, this morning I had a blinking red back battery after 15 minutes of use and the battery in the XF was still full. Should not work that way.
HDMI, on an external monitor has been improved so that you can now move around the Live View, but it's cumbersome to get to and you can't use HDMI for image playback, which to me is big deal. Pretty standard on any modern camera.
Having better overall luck with tech camera with this back over XF.
Paul C