The Z mount has changed the rules. With DSLRs, I always stuck to the Holy Trinity —that is, when zooms had to be used, as I normally would favor primes. I figured there was a good reason why the optical engineers had limited the range of the trans-standard zoom to 24 and 70, and I would never have dreamed of buying anything like a 24-120 (or, God forbid, even broader!) for fear of degrading the image quality. That viewpoint seemed to be echoed by most serious reviewers, even though broader zooms were perfectly acceptable for less demanding users or those with other overwhelming priorities, such as travelers concerned about weight and bulk.
When the Z mount appeared, and considering the type of photography I now mostly do, I figured I didn’t need any zoom faster than ƒ/4, and so I bought the 14-30 (luckily, I got an excellent copy which still gives me outstanding results) and the 24-70. Then, I read wonders about the 24-120 ƒ/4 by reviewers I trust, and I bought it to try. At the aperture values I most often use my lenses (closer to ƒ/8 than ƒ/4), it gives me excellent results, not quite as good as the F-mount tilt-shift primes in sharpness but much better in chromatic aberration (the bane of the tilt-shifts) and flare fighting. For me, it is definitely a keeper, and my light traveling kit today comprises the 14-30, the 24-120 and the 100-400. In contrast, the “heavy” kit comprises only primes.
Now, I don’t do weddings and I understand this discussion is mostly about them. I would understand a wedding photographer arguing they need very fast lenses because they often work in low-light situations and flash lighting isn’t always an option. I understand less easily why ƒ/2.8 would make such a big difference over ƒ/4. After all, it is just one stop... and at very large aperture values, the depth of field gets so paper-thin... Seeing how well the 24-120 performs wide open, I think I would use it for a wedding-like situation as I would be happy to trade off one stop for its wider range of focal length options. But, as I said, that’s all in theory, as I am not a specialist in that field!
