Pekka Buttler, February 2023
So, you have a nice mirrorless camera and a handful of lenses that you want to adapt, but the lenses are of – say – four different mounts (and you’re already thinking that you might want to try more mounts). At a minimum, you would have to get four different adapters. Instead, I suggest that you should consider getting not four adapters, but five adapters.
Hear me out, and let’s put some names to this hypothetical.
Say you currently have a Sony FE camera and the lenses you want to adapt are of Canon FD, Nikon F, Olympus OM and Pentax K mounts. In the normal order of things, the four adapters you’d need would be
- Canon FD -> Sony FE (NEX),
- Nikon F -> Sony FE,
- Olympus OM -> Sony FE and
- Pentax K -> Sony FE
Instead, I suggest it might be smarter for you to get the following five adapters:
- Canon FD -> Leica M,
- Nikon F -> Leica M,
- Olympus OM -> Leica M,
- Pentax K -> Leica M and
- Leica M -> Sony FE (NEX)
You might already see the sense of this, but allow me to spell it out:
Using the Leica M mount as an intermediate mount, and always adapting (e.g.) your Nikon F lens to your Sony FE camera using the combination of a Nikon F->Leica M & Leica M->Sony FE has a number of distinct advantages:
One, should you later get another body that uses another mount (not Sony FE), you can keep using all your lenses, and you only need to buy one more adapter. For instance, should your new camera be a Canon R camera, you would only need a Leica M->Canon RF adapter. This approach is also a form of futureproofing, as you might otherwise feel reluctant to try out another system, especially if you have a lot of money invested in adapters (see epilogue).
Two, should you be so inclined, this opens the door for autofocusing legacy lenses, as there are autofocus adapters from both Sony FE and Nikon Z mounts to Leica M (And likely more to come). Autofocusing your legacy Nikon lenses on your new Nikon Z body? Yes you can, if you have a Nikon F->Leica M dumb adapter that you can mount on your Leica M->Nikon Z autofocus adapter. Presto? Pronto! (pun intended).
Three, and this might be a minor thing, but after having used a multitude of adapted lenses (and adapters) on my Sony a7R(I) during a four-year span, I’ve noticed that the camera’s mount is quite worn. By keeping a Leica M->Sony FE adapter permanently mounted on the camera, you manage to move the point of maximum wear away from your (relatively) expensive camera body, and onto a much cheaper adapter.
Objections? Certainly. Qualifiers? Those too.
Let me try address those:
There are obvious downsides to using an intermediate mount (whatever the mount):
More adapters, more play. Obviously there is some play involved in any lens mount, as any mount with absolute zero play means lenses will get stuck and the wear on the mount will be exorbitant. A native mounting (e.g. Nikon F lens on Nikon F mount camera) means there is one mount and one mount worth of play. An adapted mounting (e.g. Nikon F lens on Nikon F->Sony FE adapter on Sony FE camera), means a double mounting and the double amount of play. If you then use an intermediate mount to combine any two adapters, you add one more mount, and add play. However, in real terms, the amount of play is more strongly influenced by the quality of the adapters involved than their sheer number.
More adapters, more tolerance. Related to the above, due to the manufacturing processes involved with adapters, adapters generally do not reach the same level of consistent precision as cameras and lenses. Hence, when you use two adapters in lieu of one, you again introduce some more tolerances.
Loss of communication. Some lenses (most notably Canon EF lenses, but also many contemporary SLR lenses from Nikon, Pentax and Sony) need to communicate electronically with a compatible body in order to function. Hence, using such lenses on a body they were not designed for necessitates a smart adapter designated for exactly that combination. That same functionality cannot be achieved when using an intermediate mount.
Vignetting. Not all mounts are created equal, and some mounts are more narrow (small-diameter) than others. While mirrorless mounts generally have a large diameter, and while the diameter of the lens’ original mount is taken in consideration when designin the lens (especially its rear element and exit pupil), when stacking adapters (to use an intermediate mount) it is possible that some extra vignetting will occur, especially with fast lenses. As long as your frame size is uniform (meaning that the lens and mount are designed for the sensor size), hard vignetting (black corners) should not occur, but if your ultimate goal is digital medium format, using an intermediate mount can not be recommended without reservations.
Why Leica M?
So you think the advantages of using an intermediate mount, but still wonder why choose Leica M as the intermediate mount? Certainly, there are other options (and we’ll get to those), but let me first mention the factors that speak in the Leica M’s favour:
First, there is the flange focal distance. The flange focal distance of the Leica M is 27,95 mm, which is sufficiently short so that almost any (full frame) lens from the film era can be adapted to Leica M. On the other hand, it is long enough so that it can be adapted to pretty much any mirrorless interchangeable lens camera (including Fujifilm G).
Second, is the age of the Leica M mount, which contributes to that a lot of lens mounts that have been discontinued ages ago have (in many cases: for decades) had adapters to allow using those lenses on Leica M cameras.
Third, even though old, the Leica M mount is still current (with three different Leica M cameras being in production as of early 2023), meaning that there are ample reasons for adapter manufacturers to offer XYZ->Leica M adapters
Fourth, the availability of autofocus adapters.
That said, the Leica M mount also has some things weighing against it:
Weakness number one is the flipside of the central strength of the Leica M mount: While the fact the Leica M mount sits nicely between the flange focal distance of Mirrorless mounts and the likely candidates for adapting makes it a perfect candidate if dumb adapting, this is also a central weakness, if that adapter should/would be anything but a dumb tube. Looking at a typical scenario (e.g., Minolta SR->Leica M & Leica M -> Sony FE), the result is two adapters that have relatively similar, short lengths, meaning that neither adapter has room for any functionality such as tilt/shift or speed boosters. Also, any helicoid adapter (while certainly possible) would be relatively constrained in the number of millimetres of extension it could offer (typically 4,5–6 mm). Hence, while Leica M has auto-focus adapters going for it, it has speed boosters (and other functional adapters) weighing against it.
Number two is that there are not (serially manufactured) adapters available for all lens mounts to Leica M. Practically, there are situations when you can find a Sony FE adapter for your non-mainstream lens mount (e.g. Altix, Argus, Konica F, Pentina, Petri, Topcon UV …) on eBay, but finding such an adapter for Leica M is less likely (as of this writing) . So even if you would use all mainstream lens mounts on your new-fangled mirrorless through an intermediate mount such as the Leica M, you would still need dedicated adapters for some lenses (or forgo that mount entirely).
Number three is the one significant lens mount that – in practical terms – cannot be adapted to Leica M, namely the Contax G mount. While there is a minor flange focal difference in Leica M’s favour, that is not enough to accommodate the needs of the Contax G mount. This might in itself be a showstopper for some.
What other options are there?
In practical terms, that very much depends on your needs and your mileage (what is in your bag), but let me summarize existing discussions as follows:
Canon EF is a popular mount with a large following. Its flange focal distance is shorter than many legacy lens mounts (which makes it attractive), but longer than some others. A definite advantage to the Canon EF mount in the availability of both smart adapters, speed boosters and various functional adapters. Covers: Contax/Yashica, DKL, Exakta, Leica R, m42, Nikon F, Olympus OM, Pentax K, Praktica B, QBM (and many more).
Does not cover: Canon FL/FD/FDn, Fujica X, Konica AR, Minolta SR and all rangefinder (Contax/Kiev, Contax G, Leica M, LTM) mounts.
A Mirrorless mount
Using a longish mirrorless mount (such as L-mount or Canon RF, 20 mm FFD) as intermediate mount would have some theoretical advantages, as it could achieve the same as the Leica M mount, but without precluding functional adapters. Such a mount could further be adapted down to those mirrorless formats such as Sony FE or Nikon Z that have even shorter flange focal distances.
Does cover: Almost everything.
Does not cover: Fujifilm G and whatever same-FFD mount was not chosen.
But as neither of these mounts are (yet) especially popular among lens hackers, neither actually forms an actionable intermediate mount, but it is conceivable that they might do so in the future.
A dedicated intermediate mount
Any adapter company that would want to launch its own intermediate mount (simply a way to sell front-ends and back-ends of adapters separately) could do so. The optimum FFD would be between around 22 mm – long enough to allow adapting down to all mirrorless mounts (but Fujifilm G), short enough to allow adapting all likely candidates, with room to spare for adapters with functionality (e.g. tilt/shift, helicoids, speed boosters)
I stared out this article by referring to its contents as some “hard-learned tips”. I did so, because the ‘strategic’ approach described in this article is not what I did when I started out with legacy lenses on moder digital. Little did I envision that I would one day be in the situation where I had a heap of lenses using 30+ different mounts and a collection of some 40 adapters. Even less did I envision that I would one day have an interest in trying out other digital, mirrorless camera systems than the ones I already had. Dang it!
In the end, I admit that my choice of extending the Sony FE system with a Nikon Z camera (instead of a Canon RF or L-mount system) was in part defined by that I was able to do so – in part – strategically (whereas any other mirrorless system would have forced me to buy a bunch of new adapters)