Afternoon fellow members! This has probably been previously discussed in detail, but I don't have time to search right away. I recently sold the last of my Nikon "F" mount lenses and am replacing with "Z" mount. Presently, my Z mount lenses consist of: 24-200 f/4-6.3 (which I'll be replacing with the 24-120 f/4), 105mm Micro f/2.8 S, and 600mmPF f/6.3 S, and Z TC-1.4. I am strongly considering the Nikon Z 100-400 f/4.5-5.6 S lens, strictly for the versatility of the zoom range covering that mid to long focal length.
The nearest camera outlet that might have a 100-400 is in Houston, TX approximately 3-hours away. There is nothing locally that I could have a "hands on" inspection, therefore, I'll have to rely on many of your experiences. I realize that the Z 400mm f/4.5 S is probably sharper and slightly better color rendition, but it's nothing I can't deal with in post editing, and if I bought it, I'd still have the void in the 300mm focal length area.
I recently watched one of Steve's Costa Rica videos where he quickly discussed using his wife's 100-400. I've watched many other videos and comparisons, but I would love to hear from those of you that have personal experience with the lens, pros and cons. Thank you in advance for your consideration!
Karl
Happy photography and enjoy your new lens. You know you are going to buy one

But here goes anyways.
I'll begin with my personal summary of the Z 100-400. It is one the finest lenses ever made. Before I continue, please don't take the technical aspect of what I write as personal. Facts are facts and none of this is meant to hurt feelings. Hopefully, depending upon your skill level and willingness to progress as a photographer, you'll find some value in what I am about to write.
So with that said, allow me to qualify that remark. It is one of the finest lenses ever made when in the hands of a proficient photographer with the pride, knowledge and skill to competently operate any camera or any lenses to its fullest potential. It does not ship with skill included.
It does not ship "soft" or as a "bad copy". Granting that some small percentage of everything created by man can be flawed, there is no recall for these lenses based upon documented manufacturing problems that has ever included any that I have used.
A huge mistake is comparing it to any other lens. Comparing it to a 400mm prime is disconnected logic. It is a zoom lens. A prime is a prime. Nobody who designed any 100-400 zoom lens intended it to be a 400mm prime lens. Nobody who ever designed any prime intended it to be a zoom. You get the idea. One close focuses at inside 2 feet, maybe 19 inches, if my memory is correct, and the other focuses at around 15 feet. Interchangeability was not the designer's objective.
Nobody ever intended the Z100-400 zoom, and any 100-400 zoom, to be suitable substitute for a 400mm prime. Especially a fast 400mm prime. You cannot compare the two without ignoring the fact that they are not designed to perform the same function.
The question seems to be does the 400mm end of it work for you. The answer to that can only be decided by the person operating it and that individuals proficiency level. That's you and only you. Competency is everything.
Personally speaking the Z100-400mm lens has never produced a poor image at 400mm except when I gave it bad instruction during the exposure and composition phase of creating an image. Simply out of building good work habits, I do not use post processing to correct mistakes. My mistakes are called "throw ways". I have never had a lens decide form one image to the next to change its mind about what I told it to do unless I screwed it up.
In the interest of fairness, I also have a Tamron 100-400mm f mount lenses that produces images indistinguishable to the Z100-400 when used properly. But I love Z system lenses and FTZ Tamron just isn't as much fun as a Z lens on a Z body. However, you would never know the difference in the results in comparable images without seeing the data showing which lens was used for which image. What defines the image is how I control light that is presented to the surface of the sensor at the moment I release the shutter.
It is very likely, given that you are asking this question, that your results using the Z100-400 at 400mm would be nowhere close to Steve Perry's results with the same gear under identical circumstances. Neither would mine. It will not be the gear that makes the difference. It will be experience and practice and dedication to the art that Steve Perry has invested that will make him images superior. It is the hands that are holding the gear and the mind making the exposure and composition decisions that are seen when one looks at outstanding images.
There are tons of them posted here on BCGF.
Your remark that you are happy dealing with less than satisfactory results, that you say you can deal with via post processing, does send up a flag from my perspective. It tells me you believe that lenses are responsible for focus when that it is the function of the photographer. We are not talking about a cheap, bargain basement knock-off lens. If you focus it properly it will respond accordingly.
I have exposed thousands of images with the Z100-400. Everything from close up near macro to TC2x and all the things it is designed to do in between. This lens is never "soft" although I can make it soft intentionally or by not paying attention to my focus. I have never had a "bad copy" of any lens I have ever touched. Personally speaking, my Z100-400, or any other lens is use, will take bad images only when I make mistakes in operating it and put bad light onto the sensor.
Usage is everything. You're the sole variable in that part of the equation. The Z100-400mm will create excellent images across the entire gamut of the it's design parameters. It only does what the user tells it they want done.
I am a true believer that before anyone pays big bucks for any piece of camera gear that paying for an education in exposure would be money better spent. Skill is always more important than the cost of a camera or lens if photographic quality is the goal.
When photography is an ego hobby then gear price is a major point of discussion.
When photographic competency and proficiency are the reasons someone loves cameras and taking pictures, then education, knowledge and pride are main talking points instead of gear.
Buying the best hockey stick will not get you into the NHL Hall of Fame if you don't know how to skate and play the game before you one. Camera gear works exactly the same way.
We all get to decide where we fall in assessing who we are and why we take pictures. There's is no right or wrong approach.
My suggestion would be for you to go to Flickr and search the gallery of images shot with the Z100-400. You will find literally thousands of images produced by all levels of photographer using the lens.
www.flickr.com