I continue to field a lot of questions that all ask the same thing: “how does [F-mount lens] perform on the Z cameras?” A few of those questions also ask about image quality. So, in the interest of clarity, here’s the T on F on Z:
- An F-mount lens will almost always have the same image quality on a Z System camera it had on the F-mount camera. I’d say that’s 100% true at 50mm and above. The very few exceptions seem to live in certain really wide angle lens designs, which may show edge issues due to extreme light angle manipulation. However, note that the equivalent Z-mount Nikkor compared to its F-mount predecessor is nine times out of ten just a better rendering lens. Best examples of that is the 24-xx zooms, which are dramatically better optically in their Z-mount versions.
- An F-mount lens—assuming it’s an AF-S lens—should continue to have similar focus speed and accuracy. The speed of a lens is mostly in the focus motor, which is in the lens, not the camera body. It appears that the Z System cameras directly understand F-mount communications and there’s no real difference in speed of that communication. In the case of the Z8/Z9, it appears that the focus decision by the camera in some cases (particularly with teleconverters) can be made a bit faster than in the D5/D6, which is surprising. Moreover, the Z System cameras don’t restrict focus sensor areas based upon aperture, which the DSLRs do. So don’t be surprised to find the Z camera focuses better than your DSLR with an AF-S lens. However, note that third party lenses reverse engineer F-mount communications. Some third-party lenses simply don’t work on an FTZ adapter, while some others do show some performance change.
- Sensor VR may make it seem like your F-mount lens is better. I’ve encountered this quite a bit since the first Z7 appeared: people weren’t aware that with non-VR lenses they weren’t getting optimal results solely due to their poor camera handling. While VR is not a panacea or cure all, it is indeed a steadying influence. However, once you get into the real telephoto zone—say 100mm+—the usefulness of sensor VR begins to decline.
- The FTZ adapter you need adds complications you need to monitor. The key to “perfect” lens adaption is that mount communications are maintained reliably. If you put a really heavy lens on the FTZ, there’s the potential for “mount droop”, which can impact how well the extra contacts maintain connection. Moreover, overall you should note that the Z-mount uses a slightly different approach to contacts (the spring loaded nubs are on the body, not the lens, whereas the inverse was true on the F-mount). One of the prime issues with DSLRs was when the contact areas on the body got dirty, communication wasn’t reliable and bad things happened. Those contacts are now at the front of the FTZ adapter. Don’t leave your front cap or a lens off the FTZ adapter! Check and clean those contacts periodically. Moreover, note that the FTZ adapter has an aperture activation arm in it for all non-E lenses. Just like in the DSLR bodies, bending this arm, even a little bit, can have consequences.
But in general, the answer to “how does [F-mount lens] perform on the Z cameras?” Is “pretty much like it did on your DSLR."
