The Z lenses benefit from 3 major things…wider opening at the rear which doesn’t limit the physics as much…newer coatings…and more sophisticated optical design software and more powerful computers to run that software on than earlier F lenses. The combination makes most Z lenses better and or smaller/lighter than their F equivalents. Not universal maybe…I don’t recall seeing any ‘We tested everything’ articles…but most of them.
The fourth, actually first in optical performance is flange distance.
I think these four nail it for the optical side. In the beginning I really didn't think too much about then flange diameter as an advantage and actually it kept me away quite some time from switching to Z.
On the one hand there was/is an adapter available but on the other hand there were so many examples in the past - with phogotraphy is only one -, that when taking a closer look, connecting technical components by means of an adapter that do not fit natively came always with some caveats, being it functionaliy, quality, reliability.
Something that actually made me think differently was something so simple as looking to the front lenses of the AF-S 14-24 f2.8 G and the Z 14-24 f2.8 S. I am an engineer, but not into opticsm but this comparison made me digging for memories of optics lessons and ... yup, the larger flange definitely is a good idea
. Suddenly it was so obvious that the bigger the hole, the easier it is to squeeze a wide FOV through it
, and what's good for the optical quality of large FOV lenses can't be bad for the long glas.
But as there were quite a number of optical marvels among the F-mount lenses, using the new technology for actually making a lens even better in IQ (resolution, CA, ...) would use the benefits only half. The other effect is that you can achieve at least similar quality with less effort, meaning it bewcomes easier and thus cheaper to build a lens of a certain quality. The truth is - as always - somewhere in the middle, i.e. lenses in a similar price level have become better optically and buying a certain level of optical performance becomaes cheaper.
One interesting example for me is the previously mentioned AF-S 180-400 f4. I am a fan of zoom lenses and during my DSLR time I was constantly tempted to get one, but the price tag made it simply impossible. After having finally gone for a platform change to Z I was in doubt of whether or not trying the Z 180-600. Yes, there is still the issue with f6.3 at the long end, but something was amazing.
The guys at
Photographylife are known to provide pretty darn comprehensive lens reviews including lab tests and because technical data number crunching is part of my job since mid of the 80's, I decided to collect their cate in a little private excel sheet to allow for easier comparison.
Sorry for not translating the table itself, but I think you get the message (Zentrum = center, Mitten = mid range, Ecken = corners)
Here are the values @ 400mm ...
And here for 560/600 mm (the AF-S 180-400 with TC engaged.
Before anybody starts complaining that I am comparing apples and oranges:
Yes, it is not really fair to put an F-mount lens with TC against a Z lens without, but if you look at it from a different perspective in terms of the technical effort to achieve a certain level of funcationality and the resulting financial effort for us to get it, I think this is still pretty remarkable. To me it's just an example for what a pretty radical change in technology can provide: similar level of technical capability while 2k versus 12k €, 2 kg versus 3,5 kg, 320mm versus 360mm, 110mm versus 128mm, ...
Yes, the results are as comparable as this kind of lab tests can be.
Knowing that Photograhylife changed their lab setup some time ago, I explicitely asked whether the valuesl can be put side by side and it was confirmewd that this is valid.
And this also gives one of the possible answers to the second part of the original question, because the Z 180-600 is not even an S lens and still gets amazingly close to one of the top notch F-mount guns.
I am happy with my Z zoom, but still stick with my F-mount oldie 500 f4 G, because it works great on the Z apart fomr one of the adapting caveats: I can't get the buttons on the lens work as configurable LFn buttons with the Z8.
May the litght be with you ...