This is not an S version. I am considering Z 20mm f1.8 S for night sky application. The nice feature of the S version: set to MF and it automatically focus to infinity! Although the Z 20mm is not a zoom lens, the price is a little lower.
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blackstar
Not to muddy your decision on the prime lens but both lenses you mentioned, and all other Nikon Z mount lenses are essentially AF-P lenses. That is, there is no mechanical connection for the focus in the lens. Instead, focus is acquired by the camera and lens's electrical communication. You can turn and turn and turn the focus dial on these or any other Nikon Z mount lens and nothing happens, (there's no movement inside the lens) when they're not connected to a body. By default when the camera turns on, the lens starts focus at infinity. That torqued enough people that there is now a feature, (released in a firmware update some time last year) that can be turned on or off called "Recall Focus Position" in the Setup Menu that remembers the focus position when the camera is turned off and then turned back on. Make sure its set to "off" if you want your camera to start at infinity with a Z lens, (or af-p via FTZ). I believe the S represents coatings that are on the lens elements. It's somewhat obscure, but if you compare the features of S lenses vs. non S lenses, Nano coating, (and other newer coatings as well) is listed on the S lenses and not on the non S lenses, (although even the non S lenses receive some coating but never Nano). Hope someone corrects me if I am wrong, but this is what I've noticed.
