My friend Uwe Steinmuller got a set of Zeiss ZF lenses to demo for a few days, so he graciously invited me to tag along and try them out too! He didn't have them but for a few days, so we we decided to meet in San Juan Bautista and shoot together for a few hours one morning.
I'm not going to get overly flowery in my descriptions since I really didn't spend a lot of quality time with them, but I will share my initial overview impressions. Note that I had decided just a few days prior to this to purchase the Zeiss ZF18 for my own kit bag, and find it a great addition for me.
Here are my initial impressions:
ZF15 is a very large, massive lens, but offers excellent performance for a hyper wide. Shows a little bit of CA, some curvature of field and relatively easy-to-correct barrel distortion;
ZF18 is a relatively compact lens by Zeiss standards. It's performance is not quite as good as the 15, but still very good. Shows a bit more CA, some curvature of field and harder to correct wave-distortion;
ZF21 is about the same net IQ as the 18, just less FOV, perhaps even more pronounced wave distortion than the 18. It is a physically longer, larger lens than the 18;
Nikon 24 PC is very, very good. Slight barrel distortion, slight CA. Shifted it remains very good to about 8mm, and fully shifted nets a little wider than the 15 by itself, about as good at the corners, but more CA at max shift edges.
Nikon 35/1.4g: Excellent centrally, even wide open, but edges are soft at wide apertures. Edges get good around f4, and best at f5.6/8, but never match the center performance.
ZF35: Horrible resolution and excessive CA at 1.4 and 2 across the image, totallyt unusable at these apertures by anybody's standards. Fortunately edges clean up at f2.8 to about where they're as good as the Nikon edges get at any aperture, but the center is still pretty bad, what I would consider barely usable. But at f4 it all of a sudden gets very good a the center to excellent at edges -- very weird behavior... At 5.6 and 8 it is sharper at its now excellent edges than its very good center -- and clearly sharper than the Nikon at the edges -- but the Nikon remains sharper centrally.
PS: Uwe had his 17-35 Nikkor Zoom there, so we did a quick comparison with it too: For a zoom, this is a very good lens! Has soft extreme edges at all focals, but centers are excellent. Image starts to fall off about 2/3rds out, but still quite usable all the way to the extreme edge. Also has pretty heavy CA at edges, but that is easy to fix. Probably the biggest issue is distortion which is heavy at all focals, but we expect that with a wide zoom and it is correctable. Wider at 17 than the ZF18, but I suspect after corrections they will be about equal. The zoom is sharper at the extreme edges at 17mm than the ZF18, they're about equal and very good centrally, but the ZF holds its center sharpness further toward the edges until it hits its wall at the extreme edges. Bottom line if I owned this zoom, I probably would not buy a ZF18, or a ZF21, or even a ZF35! But then it's a bigger lens than the 18, and with the 24-120, I doubt I'd ever carry it for a wide only.
If it weren't so big and over twice the price of the 18, the 15 would be nice to own -- but then I rarely shoot that wide and have the 24 I can shift for essentially that same FoV if/when I need it. For travel, I like the smaller size of the ZF18, which is one main reason I bought it. With the 21 and 18 performance being so close, and the 18 being both smaller and wider, the 21 holds no interest for me personally.
The real surprise for me here is the 24 PC -- they get a bad rap, but this copy of mine shows pretty well I think. Especially shifted -- very good to about 8mm of shift, which basically allows me to mimic the 15 FOV with a shift-stitch if I ever need it.
Links to nef raws for each of these lenses. Note we aren't offering test shots per se, just shots from the same tripod location so you can evaluate the FoV, distortion and basic IQ. Also, it was a partly cloudy day so clouds were moving in and out of the Sun, hence lighting changes between most of these shots -- for this reason I also used matrix Av metering for all frames and let the camera do its thing. All were at f5.6 unless otherwise noted:
ZF35 at f2.8 just for comparison (the f1.4 and f2 are significantly worse): https://dl.dropbox.com/u/8029401/D8A_0744.NEF
Added for reference ZF35 at f1.4: https://dl.dropbox.com/u/8029401/D8A_0742.NEF
Nikkor 35/1.4 g: https://dl.dropbox.com/u/8029401/D8A_0732.NEF
Nikkor 24 PC-E -- 3 images here, center plus full left and right shifts: