Replacement Lens Feet
Even though I don't use any products actually made by Arca-Swiss, I'm a dedicated user of products compatible with the Arca-Swiss dovetail system. I'm guessing many of you are too. Adding a mounting plate is a proven way to solidly couple just about anything atop your tripod head. But if what you want to mount is a lens with a removable tripod foot, your best bet isn't to add a mounting plate to the bottom of that foot; it's to replace the foot itself.
You can get a mounting plate to fit all sorts of things. I used to joke that I had a plate on just about everything I owned other than my toothbrush. But every time you add something to what you want to mount, you create another place where things could wobble or flex. Companies such as Really Right Stuff and Kirk Enterprises custom manufacture plates designed to fit a wide variety of professional and consumer photo gear, but in the end a plate is only as secure as the screw or screws holding it on that gear. And no joint is perfect, so fewer joints is clearly better.
That's why I'm glad that a few companies also make replacement feet for many lenses that come with removable feet. Such lenses are typically heavier lenses that can benefit from a mounting point that balances the weight of camera plus lens better than would attaching to the camera itself. That also means they are the very lenses that put the most stress on your tripod system because of their greater weight. Removing the stock foot completely and replacing it with an aftermarket foot with an integrated dovetail means I have one fewer joint when such a distinction would matter most.
You can get replacement lens feet from Kirk, Really Right Stuff, Markins, 4th Generation Designs and others, but my favorites are those made by Wimberley. As the maker of the well known Wimberley gimbal head, this is a company that has put a lot of thought into how best to support big lenses.
Wimberley replacement feet feature low profile designs to keep the center of mass low. This isn't always an ideal strategy mind you, but is an admirable design goal. Some Nikon (and Canon) original feet force your precious lens to perch several inches above the top of your tripod head. They do so to permit the hood for that lens to be reversed back over the lens for storage, nesting between the lens and foot. Shorten the foot a little and it would hit the hood when trying to mount it reversed. In such situations Wimberley always opts instead for a foot that is short enough to clear the hood on the inside rather than the outside. In the case of the Nikon 500mm AFS at least, this positions it almost too close to the lens body making it difficult to use as a handle for carrying the lens but I rarely carried mine this way anyway when I owned one. I agree with Wimberley that it's more important to design a foot that maximizes stability when shooting, and that means low profile.
Perhaps more importantly, Wimberley feet also include safety stops screwed into fore and aft ends to stop your big lens from falling to the ground. The one drawback of the Arca-Swiss system is that while the open-ended jaws of the clamp allow your lens to slide forward and back to better balance it, they also could allow it to slide all the way out, with disastrous consequences. I feel much better knowing that my gear won't crash to the ground while being carried atop my tripod. Markins clamps feature an integrated stop pin in the middle that can serve the same purpose but tends to just get in the way most of the time. The Wimberley approach of adding stop pins only on gear that need them seems more well thought out to me.
Too bad manufacturers don't simply build Arca-Swiss dovetails into the bottom of their cameras and lenses. Not yet at least. I long for the day when professional cameras and lenses have mounting dovetails built in.