The world of lens adapters is a risky place. Behind-the-scenes, you’ll never find the creator of a lens mount standard being delighted to share data with other companies trying to adapt lenses. A basic principle of lenses as they exist in the profit sector, is that they obviously aren’t worth what you pay: instead, their high price tags compensate for lost profits in R&D and manufacturing spent on revolutionary camera bodies, with each new version sold as a “loss leader.” In other words, lenses weren’t invented yesterday, and they aren’t all that complicated (just ignore the marketing hype, especially Sony’s “G Master” racket). Whereas, camera bodies are technologically cutting edge, expensive to make, neck-and-neck in competition, and can’t afford to slack.
So, there’s no winning incentive for folks like Canon to help a company like Viltrox sell affordable lens adapters (even though a fringe benefit would be to promote their emerging lens mount standard, versus others like E-mount, Micro Four Thirds, etc.). Canon would rather that people buy Canon’s own lens adapters, which leaves the like of Viltrox to “reverse engineer” the lens mount standard without any help from The Creator.
Normally, results are mixed at best, especially when it comes to adapting third-party lenses like Tamron, Tokina, etc. who were already in the same boat: trying to reverse-engineer the official spec. But the world is a little better place when it comes to Canon’s new RF mount, used on cameras like their R5 that I previously reviewed here. Compared to adapting active Canon lenses onto Sony or Micro Four Thirds mounts, for example, Canon RF to Canon EF is (at least thematically) a pass-through of prongs: those electrical contacts are passing along instructions and metadata from Canon to Canon, instead of translating that information across divergent lens languages.
That’s why this Viltrox EF-EOS R lens adapter implicitly poses less of a risk in the compatibility department, and here you see it paired with one of my several Tamron lenses that do work in all categories of electronic control: aperture, focus, and in-lens image stabilization. I have seen sporadic reports of incompatibility with third-party and even Canon-native EF lenses, but they currently feel like rounding errors, attributable to something else. In other words, so far, the whole universe of adapting EF to RF mount is smooth sailing.
After that compatibility threshold, it comes down to build quality and, most critically of all, snugness of the lens to twist-and-click into position. So far, there too, all good.
It might be that Canon’s own EF to RF mount adapter, costing almost twice as much as the Viltrox, is marginally better. But they have had supply issues, backordered for long stretches, so even if this Viltrox is a stand-in for now, you can’t go wrong because if you go with the official Canon adapter later on, you’ll have this affordable backup anyway.
And that’s the end of the road right now: you don’t want to buy into Canon’s outrageous gouging behavior when it comes to their otherwise innovative EF to RF mount adapter that exploits the flange distance gap with a slide-in, behind-the-lens variable ND filter. Reason is, Canon stubbornly refuses to include anything to plug up the hole when you don’t want to use the ND filter (i.e., very often). They force you to buy an additional product for $130, as if it’s “optional” for a $400 product that’s opportunistically priced to begin with. And there are no alternative choices for drop-in filters. I look forward to Canon feeling the fire whenever Viltrox and the like step up and release their own third-party equivalents, spending those extra pennies it takes to plug up the hole.