One advantage of adapting lenses with the Leica M mount to L mount cameras is that there’s enough space to add a helicoid between the lens and the body mount.
Basic M to L adapters have a fixed spacing of X mm. If properly made, the distance markings on the lens will be accurate. The most important focus position is infinity because most users will just spin the lens to the infinity position and expect it to be in focus. Some poorly-made adapters get the spacing wrong, making it impossible to hit infinity focus (if the spacing is too large) or to focus past infinity (if the spacing is too small). Both are bad but not being able to hit infinity focus at all is worse.
The official Leica adapter is a fixed-distance adapter, so it’s not included here, but it is one of the best-made adapters. On Leica L-mount cameras (CL, TL2, and SL series) it transmits the 6-bit lens encoding on the lens mount to the body, but this sometimes causes problems on lenses without 6 bit encoding. I’ve had my SL lock up, apparently getting stuck trying to read a non-existent 6-bit encoding on a Voigtlander lens.
I suspect the reason Leica never introduced their own adjustable M to L adapter is that the lenses aren’t perfectly optimized to focus closer than the focus range provided by the lens’ helicoid. If this bothers you then don’t do it, but it doens’t bother me.
Most of these adjustable. adapters use the same design for the helicoid close-focus mechanism. Light Lens Lab not only is the best made, but it’s also a unique design, including a focus lock so you know when the lens is in its ‘normal’ position. This is both a blessing and a curse, depenidng on whether your lens already has an infinity lock position.
To use these adapters for close focus, adjust the lens focus to the closest position, then use the adapter’s helicoid to focus the lens even further from the body. There’s no marking on any of the helicoids because the actual object focus point depends on the focal length of the lense being adapted.
Light Lens Lab
This really is a new design. The locking tab is nice until you use it with a lens that also has an infinity lock. The two want to sit in the same position. For lenses without an infinity lock, this is the best-made adapter.
This is the only adapter I haven’t needed to open and re-lubricate.
Generic Adapter
I bought mine from Amazon but you can also get them from AliExpress for a little less.
7Artisans
Same design as the generic adapter, but relatively poorly machined. The surfaces are a bit rough with visible machining marks, and the edges of the components can be sharp. The also applied much more greast to the helicoid than is necessary, and it’s a particularly thick grease which made the helicoid hard to turn.
I ended up taking it apart, removing the old thick grease, and re-greasing it with Helicoid XP
Hoage
The Hoage design is the same as the generic adapter and 7Artisans but has noticeably better machining. The surfaces are smooth and the edges have no burrs. However, the grease was about as thick as the 7Artisans, it wasn’t leaking out like the 7Artisans.
I did open it up and re-grease, again with the Helimax XP.
Fotodiox
This is similar to the 7Artisans and Hoage, but it doesn’t have a stop at infinity, so it can focus past infinity. I suspect they worried about messing up the infinity focus and getting a bunch of returns, but focusing past infinity annoying because it means that if you put the lens in the ‘default’ state (ie. the closest focus to the body) infinity focus is off.
In addition to re-greasing the helicoid, I ended up scratching a mark on the body of the adapter to indicate the correct position for infinity focus.
Conclusion
Which is best? If you don’t mind the focus lock, the Light Lens Lab is the best. But if you don’t like or can’t work with the infinity lock, I recommend the Hoage over the other units because of its better machining.
Steven Kasapi 