If you can use a screwdriver and a lens wrench / lens key then you could mount your own lenses. There's no helical on the Arca mount, so as long as it's machined correctly my cat could do it.
I'm sorry, but the attitude that 'it has to be done at the factory' is the photographic equivalent of 'rust-proofing' in 'The Dealership' epsiode of Seinfeld*. I've mounted/unmounted any number of lenses in a variety of helicals/mounts/lensboards over the years without a hitch; I just remounted a 47mm digitar onto a Fotoman helical and mount for a friend, adjusted the lens for infinity focus and bingo, she creates tack sharp images as every bit as wonderful as those I've seen produced by the same lens in Alpa and Cambo mounts - and for a whole lot less than what the 'big three' charge.
Since Henry Fox Talbot fell head first out of a tree we've been tweaking helicals and taking lenses apart, cleaning the shutters, screwing them back together, carting them around in cases on planes, trains and automobiles, knocking and bumping them, getting them baking hot and freezing cold, soaking wet etc. - but now in the digital age they have all suddenly become so fragile and delicate that attaching them to a dumb old helical and then to a piece of machined metal (and perhaps installing an angled sync and cable release socket) is, apparently, beyond us. This can now only be done in hermetically sealed rooms by folks in white coats with PhDs and exotic accents (at least, that's the scenario I imagine). This is utter madness.
Have you used an Arca R system at length? Have you (personally) mounted and calibrated an Arca R lens for use with an IQ180 or Aptus II 12?
First let me say that I understand your indignation and your comments about dealers (I love Seinfeld) is understandable; I assume you've worked with some shoddy ones (of which there are many). I would ask you however not to generalize those experiences on all dealers, especially not if you've never met or worked with them. Search my name on this forum or the general internet, call me, stop by the office, or ask any of our customers here or offline and you will find your statements are not true of me. This is NOT an undercoat to a car, and I would not sell or push the equivalent of this.
The precision required to place infinity on an Arca R mount for f/8 is much higher and more knowledge-intense than your statement implies.
First, several of these lenses exhibit fairly significant focus shift, so the testing of the proper placement of focus cannot be done wide open, but because testing stopped down increases DOF the analysis of proper infinity is most assuredly non-trivial.
Second, the level of possible accuracy on an Arca R is extraordinarily high. If all you've used is the helical on the Fotoman or the Alpa HPF ring then you haven't experienced in practice how minute the possible level of adjustment is. The level of precision, when using multiple lenses, requires that the calibration of the mount itself is less than one tick's worth of focus. For reference on a 47XL the difference of one tick when focused at 150cm distance (5ft) is 1 cm of subject distance. How would you propose the end user calibrate their focus to this accuracy (remembering they must do this while stopped down)? The mechanical mount itself is machined about as precisely as can be hoped, but even from one specific lens to another specific lens the variation is such that every lens MUST be calibrated to the mount. This is done by Arca by means of shimming the rear element of the lens under the retaining ring to insure perfect placement of that lens both fore-aft and is then tested to insure perfect planarity.
I agree that for the majority of photographic history this level of mounting precision was not remotely necessary. Required precision of mounting varies as a function of focal length and with larger formats of film the focal lengths were longer. With a 300mm lens an accidental 1 degree of tilt and a fore-aft movement of 1mm is not of much significance. With a 23mm lens an accidental 1 degree of tilt is a huge change in the placement of the focus plane.
Required precision of mounting also varies as a function of resolution you wish to achieve. If you have a slightly misaligned lens with a P25 (9 micron, 22mp sensor) it will not be as evident as with an IQ180 (5.2 micron, 80mp sensor).
Required precision also varies based on how you will be establishing/evaluating focus. With an 8x10 you were focusing on a ground glass; regardless of where the lens is placed you were establishing and evaluating focus directly. With the Arca and other helical mounts one of the points of the system is to be able to set the focus indirectly (e.g. using a distometer or pre-established hyper focal distance) - the accuracy of that method of establishing focus is entirely dependent on the calibration of the system.
Required precision also varies based on aperture used. Since a higher res back will show diffraction at an earlier aperture there is a strong tendency of our IQ180+Arca users to use f/7-f/9 far more frequently than our customers with for instance an P25+Arca. At f/8 there is very little room for inprecision as compared to f/11.5.
Whilst I understand that this is a lucrative part of the business model of these companies … at the end of the day, from the perspective of the end-user, this is all about choice (or, more correctly, the lack of it). If you want to send your lens away to be mounted then great, go for it - but if not, wouldn't it be nice to have the choice to do this yourself?
I can assure you that a few hundred bucks for a few hours of service does not qualify as the lucrative part of Arca's business model. This is a very small company and their staff-time-at-the-workbench is their single sparsest resource (ask anyone who is on the waiting list for a D4 head). Selling a quick release plate at the prices they charge - THAT qualifies as a lucrative part of their business :-).
Anyway, based on my experience the purchases of Arca value very high precision over the flexibility of being able to change out lenses themselves. If you want a more DIY solution the Fotoman or Linhof (or a traditional view camera) is probably a better choice.
The precision Arca offers is very very high. To attain that requires some compromise. If you think the precision is more than is needed (for your applications and needs) then you are probably right, in which case those compromises might seem silly (or greedy). Please respect that there are others who in fact do need/want that precision for whom the cost and reduction in flexibility/DIYness is perfectly acceptable.
Plus I still don't know (haven't asked since this isn't my customer) whether (for sure) Arca would sell the parts by themselves at a reduced price. Rod might be able to comment?