Just wanted to report on my experience with the Miller CX6, Miller CX10, and Cartoni Focus 12. It was a really difficult task to compare performance because the differences, while not negligible, are also tough to quantify. I would have to essentially say that it's a wash in terms of performance once everything is set up right. There are situations in which the Miller might give some bounce back when the Cartoni does not and vice versa. I'd therefore like to instead focus on usability and ergonomics.
The first thing to note is that these two systems seem like they each incorporate complimentary features which do not make much sense in the absence of the other. The Miller has 16 discrete counterbalance settings, which only allow for a faster workflow if you can reliably place the payload each time, which is made more difficult than it needs to be due to the plate design. To be fair, it's not that difficult to eyeball a particular landmark in the plate's travel (e.g., the end of it lines up with X), but it seems an oversight not to include measurement markings on the body of the fluid head so that you can quickly and reliably place the plate each time, especially if you're working with somebody who doesn't know your gear. On the complimentary end of this equation, the Cartoni has continuous counter-balance controls but with discrete plate placement (with the Euro style plate at least), the latter of which is not that helpful unless you can quickly dial in balance settings. There are 16.5 turns of the counterbalance control in my observation with each turn consisting of 24 clicks of the dial. Much like placing the Miller plate, you can get close to where you might have had it previously for a different setup, but it is tedious to count out turning the counterbalance wheel and it will inevitably require some fine tuning once it's set. The positive that must be said of this is that you at least
can fine tune.
One other thing that is notably present in one that the other does not have is a zero drag setting. Center of Gravity is much easier to establish on the Miller because you can set tilt drag to zero and get a much clearer sense of where the weight is overtop the fluid head. On the Cartoni, the minimum drag setting is comparatively substantial, so getting a clean center of gravity is tough to do, especially with a light camera. If there were angle notches so that you could see where +/-5 degrees is, for example, and compare how quickly the head fell to +/-90 degrees respectively, then it might be a bit easier to place the package at the center, but there aren't any such markings. Consequently, I found that my counterbalance was difficult to get correct. I would find after some time of using it under higher drag settings, that things just weren't right and I'd nudge the plate a bit forward or backward to compensate. This is really not ideal as it's just throwing more variables in to a process that should be minimizing variables as it progresses.
I also found through this testing that I prefer discrete drag settings. I do not need an analog control for this and, in fact, I think usability suffers due to the fact that getting even pan and tilt drag settings is harder than it needs to be. You just have to set it, try it, and then re set it. The Focus 12 also has a tedious pan drag control. It is not easy to manipulate and requires extensive rotation to move across its entire range.
To address the drag range of the heads, I would say that the CX10 with its 0-5 drag settings is a simple extension of the 0-3 drag settings on the CX6. That is, 3 is equal on both. 4 and 5 on the CX10 go beyond the drag of the CX6. The CX10 and the Focus 12 feel similar in their range of drag. The Cartoni tilt drag control turns 2.5 times and I found turning it once from minimum feels roughly equivalent to the 2 setting on the CX10 (1/2.5 = 2/5, so that makes some sense) and the pan drag control has 50 clicks and I found that clicking it 20 times feels equivalent to the 2 pan drag setting on the CX10 (again, 20/50 = 2/5).
On the Miller, both the pan and tilt lock levers are tightened in the reverse direction than is typical (you have to turn them counterclockwise to tighten). The tilt lock lever feels more like a knob, as it has what I would call an excessive range of travel. The pan lock lever feels more like a lever, but again, it's reverse. The Cartoni locking levers both function like levers in that you just need to move them a little bit to engage, however they are a bit small, made of plastic, and feel somewhat fragile. Having said this, the locks actually do their job better on the Miller. I can fairly easily pan and tilt with the locking levers engaged on the Cartoni.
Overall build quality I would say is about even. Though the Cartoni has more plastic on it than the Miller, it still feels very robust (aside from the locking levers). The camera platform is a good deal larger and has about double the travel of the sliding plate on the Miller. The Cartoni also has fewer clinking and clunking moving internal parts. On the CX10, I accidentally slipped drag settings into spots that were in-between discrete steps and it severely mars the performance. You might not notice this because things appear engaged, but a small extra push might be needed to get it fully engaged. This doesn't become obvious until you go to pan or tilt and there's a bunch of slop present that you might not expect. Easy to fix, but also easy to do by accident as the tilt drag and counterbalance controls are a bit difficult to manipulate.
What the Cartoni
does have going on in terms of build is some off-putting "things reaching their limit" type concerns. I'll explain. When tightening down the the pan drag to its max, for example, I can hear a popping noise. I think it's an air bubble in the fluid getting compressed and popped, but the whole notion of continuous controls leads to this; the pan/tilt drag knobs, the counterbalance knob, and the tripod legs too (the tripod is Cartoni's Stabilo) all have controls where you tighten things down or loosen them up. It is hard to know where the end of the movement should be, as tightening them makes them progressively harder to manipulate anyway. Sometimes they are difficult to get unstuck from the end of their travel. I can state confidently that there is no way my girlfriend, for example, would be able to manipulate the Cartoni tripod legs or controls on the head if it was me who just tightened things down. The Miller's controls slide comparatively easily from one setting to the next and the Manfrotto 536 tripod I paired the CX10 with has lever locks that are much easier to use than the friction locks on the Cartoni Stabilo. I think this is going to be a matter of getting used to how things "stick" and not tightening them down quite as much as I might otherwise. The tripod legs in particular are a complete pain in the ass in this regard.
A comment on the mounting plates. I was able to slide Miller's mounting plate into a Manfrotto head, so that's nice. In order to mount my DSLR with the Miller, I had to remove one of the mounting screws on the mounting plate. On the Cartoni, while I only used one of the screws, I didn't need to remove the other one for there to be room enough to mount it to my 7D mark ii. I also think the Cartoni handled lighter loads better than the Miller, for one because the plate on the euro style head actually has considerably more travel than the sliding Miller plate does and the continuous counterbalance has a bunch of steps in between 0 and 1, which the Miller does not. The screws in the Miller plate are also recessed quite a bit, to the point that I couldn't get in there with a US quarter to adjust the screws. A penny worked though.
The pan bars are each a bit different. Neither are Manfrotto compatible (though in the case of the Miller, it's just the screw on the Miller being larger; the rosette is the right size). The Cartoni comes with a telescoping bar, the Miller's is not. The Miller's handle is made of a substantially thicker rubbery material than the Cartoni. It's certainly a nicer, slightly plusher feel, but it might not actually matter or buy you any performance, particularly when you consider that the more elastic materials there are interfacing between you and the camera movement, the more opportunity for elastic looking movement there is. Not noticeable in this case. I probably would not use a telescoping bar for the same reason. It introduces more elastic play and it also changes the balance of the package.
The one thing I'll comment on in terms of performance is that my Cartoni has more static friction than the Millers did. What I mean is that it takes more force to get started from a standstill, at least for pans. Using a rubber band to pull the pan bars sideways shows it stretching considerably more when pulling the Cartoni than the Millers. The Cartoni gets going with a bit of a start whereas it feels smoother on the Millers. I think this matters alot, but I think it could also be unique to my copy of the Focus 12. I previously used one that did not have that feeling to it.
On adapting the CX6 to a 100mm ball mount: I used the Miller 378 75mm to 100mm mount adapter that they provided with the loaner and found that it did not fit very well at all with the Manfrotto 536. It worked in that it kept the CX6 attached, but the adapter did not seat into the 100mm ball mount nicely (it was sitting lopsided) and it felt a bit janky. Perhaps Manfrotto's own 75mm adapter would be better here.
To sum up, I have to decide if I'm returning the Cartoni in favor of the Miller or not. I would perfectly happy with the Cartoni if it had a zero tilt drag setting. Not having this feels like active sabotage of its usability. It's real-deal continuous counterbalance feature is completely hamstrung by balance being difficult to gauge on it and I'm a bit mystified that this hasn't been obvious to those who have used this system in the past.
To further conclude, I'm settling up to the fact that fluid heads in this range do not perform as I would hope at telephoto focal lengths. Settling and rebound is noticeable on both the Miller and Cartoni. Perhaps it's different on an O'Connor