The zoom ring is not particularly stiff, but neither it is particularly smooth to operate. I guess that a looser zoom ring might have caused lens creep, so they opted for a medium stiffness. I don't have the 24-120 to compare, though. It's more or less comparable to the 14-30 and 24-70/4, maybe a tiny bit stiffer than than.
Anyway, I have played a lot with this lens in the past 3 months on my Z6, and optically I can offer the following considerations:
NAKED LENS (no converters)
- The lens is balanced and handholdable, ergonomic and a great compromise in weight.
- Quality at long distances is very good at all focal lengths and apertures. It's already excellent in the center from wide open, and slightly benefits from stopping down only in the corners.
To make a comparison, at 100mm it's better at full aperture than the Z 105 MC at 2.8: unfair comparison, maybe, but considering that the macro lens is one of the sharpest 105mm lenses ever... The Z 105MC still has a slight edge if stopped down, though (as is to be expected).
- Image quality only degrades a bit at very short focusing distances and towards 400mm, but still very reasonable in the light of the very short minimum focusing distance: and this is an advantage compared to the fixed 400/4.5, because it allows for nice "almost macro" closeups.
- Focusing is quite fast, although it may hunt a bit at the long end in low light before grabbing focus: this is also due to the Z6, and everything points to better (and almost impeccable) behaviour on the Z9.
WITH 2X TC
- Losing two stops and becoming f/11, clearly the focusing speed suffers even in normal light conditions (again, it should be better on the Z9)
- Quality when using the TC at lower focal lenghts is very good. There is absolutely no difference in sharpness between shooting with the bare lens at 400mm and the lens @200+2X TC, which is telling on how good the TC is
- Quality definitely takes a hit in the 300-400mm range (600-800mm equivalent), and especially at short distances. It actually very much depends from situation to situation. But still, it's better than cropping, especially at long distances: the difference between 800mm with the TC and a 2X crop sees a reasonable advantage for the TC
- While the bare lens is very good at full aperture, stopping down half/one stop is rather recommended with the TC to improve sharpness and reduce slight instances of bloom
- As I said before, "it depends from situation to situation": ideal light will yield good results. But anything less than ideal will amplify the TC limits. Low light? Flat results. Contrasty light? Some loss of contrast due to blooming. Terrain heat/haze/humidity? Even worse. This last warning goes for ANY long telephoto, of course, but I feel that together with the loss of quality induced by the TC it's amplified. Some close shots I have done to small animals @800mm in hot days and harsh light were not exactly flattering, and actually quite soft. A partial remedy? Stop down to f/14-16, and then go heavier with the sharpening in PP.
- Bokeh is very much affected by the TC, becoming nervous and generally distracting
In general, TLDR: very good lens, but if you plan to use it with the 2X TC don't believe the hype. There are some internet reviews which say "I didn't see any image quality or performance hit with the 2x TC, it's a miracle!". No, sorry, the difference can be seen. Usable, but still not perfect.
