I have a Z9 and a Z100-400. I'm planning to mount the combination on a tripod and perhaps a monopod. I have rarely used a heavy lens. How should I mount the camera and lens, camera on the tripod with lens unsupported? or lens on the tripod with the camera unsupported? Your responses are appreciated.
I also highly recommend the Wimberley Monohead. I had the RRS equivalent for a few years, but the Wimberley is much smoother to use.
I would add that I always use the 100-400, 400 f4.5 and 800PF on Z9 bodies handheld as they are so light and well balanced, but I can see situations where you might want to use a monopod.
Don’t fear: not supporting the camera body. That’s less strain on the mount than some handhold-only lenses. But do avoid handholding that combo from the body only, in a level configuration.
What perhaps would have helped was if you had phrased you post "how to support a Z9 and 100-400" -- then it would have been much more clear.
DO NOT support this lens from the camera body - this is "nuts" and ends up with a very out of balance set up AND is simply not the way these systems are designed to be used. Whenever a lens has a foot you should use the foot to support the lens/camera and NEVER the camera.
Basically the combination of a Z9 and 100-400 is relatively very light and easy to hand hold (well compared to a 400TC or 600TC or the 800PF) - but you can very easily screw in a monopod into the standard Nikon Lens Foot on the 100-400 OR screw on a lens plate compatible with your tripod/monopod head to this foot and use it supported that way. However, many of us choose to replace the foot with a compatible Kirk Arca Swiss style replacement foot with built in QR socket. {yes other replacement feet are available} -- you have to make sure that the foot works (ie does not clash with the vertical grip on the Z9 - I use Kirk and know there are no issues).
It is then for you to choose what to use on your monopod, tripod, ground pod or panning plate and there are endless choices. I use a combinations of AcraTech heads, gimbal heads and more traditional tilting monopod heads on my gear -- all with lever style arca-swiss clamps.
Lens and replacement foot shown on the left
Yep. If you're hand holding, you can hold by the lens, but the lens absolutely is the pivot point with longer/heavier lenses and the mount will support the weight/balance of the camera from the lens better than supporting the weight/balance of a long lens unsupported from the body only.
Perhaps you miss my main point.
To the best of my knowledge Nikon does not quote a safe weight limit for either an F Mount or Z mount body lens flange.
Nikon quote a safe weight limit for the lens mount of an FTZ.
In that case I am afraid that it is a big assumption that the FTZ, Z30, and Z9 have similar weight limits for the lens mount. In reality, the FTZ is designed to be kind of fragile so that if the set up is dropped, the FTZ would break and absorb most of the damage. There are a couple of posts in the last day or two about that on FaceBook Z9 groups.
A couple of local Nikon reps have demonstrated this a few times. They would mount as heavy as a 600mm/f4 on a D850 or Z9 and then pull out the rear LCD. They would hold the LCD up to sustain the entire heavy set up and dangle that around for a while to demonstrate how durable the swivel LCD is, but they do tell you not to try that at home.
Personally, I have the 70-200/2.8 S and 100-400 S. I wouldn't hesitate to use the Z9's camera strap to sustain either one of those lenses mounted. In fact I have done that in multiple occasions, especially when I need to switch between the 70-200/2.8 and 24-70 or 24-120. Personally, I wouldn't do that with a 600/4 or 800/6.3. However, as a general rule of thumb, whenever there is a tripod collar, I would mount a strap on the collar to sustain the lens with a camera body mounted on it, be it my Z6 or Z9. Sometimes it is not very convenient to do that when I need to switch between collared and collarless lenses.