Introduction

Since I bought my first E-mount camera seven years ago I have been using adapted M-mount lenses. Missing Exif data have always been a nuisance though and while the “Lens Compensation” camera app was a ray of hope, it didn’t exactly work all that well.
Now TTArtisan came up with a product which I have pitched to so many manufacturers before: a semi programmable Leica-M to Sony-E adapter. Let’s have a closer look!
Update May 2023: TTArtisan released an improved MK II version of this adapter, I summarized for you what has changed
How does it work?

The TTArtisan M->E 6-bit Adapter let’s you use your Leica M lenses on a Sony E mount camera – nothing special, adapters that can do that have been around since forever – but this one has two additional functions:
a) it will translate the 6-bit codes on Leica M lenses to Sony lens exif
b) if you use a lens without a 6-bit code you can set one of the typical Leica M focal lengths (28/35/50/75/90/135) via a small wheel
What are these 6-bit codes?

In 2006 with the introduction of the Leica M8 a 6-bit code system for M-mount lenses has also been introduced which allowed for the application of in camera correction profiles (which were badly needed when using some of the Leica M lenses on a digital camera) as well as additional lens exif data in the digital files.
If you are looking for a more detailed explanation have a look here.
Using 6-bit coded lenses
Now if you attach a lens equipped with a 6-bit code this adapter will translate this code to lens exif data the Sony cameras understand. Every lens will be registered in the exif data as “Leica M <focal length> <max. aperture>”, so you don’t get the lens name (like Summicron or Summilux) or anything additional. For example the Leica 90mm 2.0 Summicron-M will show up as “Leica M 90mm F2.0”.
You can use the aperture wheel on the camera to change the aperture value which will be written in the exif data. So if you want to track at which aperture values you shot this is a handy feature.
When you put a lens with a different 6-bit code (or you use the wheel on the adapter to change the focal length) you have to detach the adapter from camera first for these changes to be registered. Pressing the lens release button and slightly rotating the adapter back and forth is sufficient here.
Update: the Mark II version of this adapter features a small reset button, if you change the lens just press it and you are good to go.
Using lenses without 6-bit code
If you are using a lens without a 6-bit code the adapter will use the focal length you set on the small wheel on the side of the adapter. Only the six typical Leica focal lenghts are included though: 28, 35, 50, 75, 90 and 135mm.
Here the lens name will be registered as “Leica M <focal length> F1.0”, you can use the aperture wheel on the camera again to have any aperture value between f/1.0 and f/16 written in the exif data.
The focal length set will also be passed on to the IBIS setting to allow for the correct amount of stabilization.

Update: the wheel on the Mark II version of this adapter features click-stops, so it is less likely to accidentally change the setting (never happened to me personally though).
Compatibility
I already received a pre production sample before and there were two things I didn’t like about it: the opening of the adapter was too small, so I encountered additional vignetting with many fast and/or longer lenses and it only really made sense if you had 6-bit coded lenses.
As said before we got a wheel to set the focal length now and I am also happy to report: the opening got much bigger.
With the pre production sample I encountered severe vignetting with the Leica 90mm 2.0 pre Asph, the MS-Optics 135mm 2.4 and light vignetting with the MS-Optics 50mm 1.0 and the VM 75mm 1.5. All of these – except for the MS-Optics 135mm 2.4 – work flawlessy now without additional vignetting.
There are some more lenses with a big entrance pupil I think might encounter some issues but I don’t have them here to check: Leica/7Artisans 75mm 1.25, Leica/Zhong Yi 90mm 1.5, TTArtisan 90mm 1.25 and the 50mm f/0.95 lenses.
Out of all my M-mount lenses I also had issues with the Leica 90mm 2.0: when using the original uncoded bayonet one of the screws is being recognized as a “1” and therefore the adapter thinks you are using a Leica 90mm 2.8.
This adapter is also a little bit on the short side, so might not be the greatest choice if you want to use a lens with a floating elements design. On the other hand it could therefore be a great choice if you are looking for an adapter to use with your Voigtlander VM 35mm 1.7 + 5m PCX filter…
By the way, this adapter only weighs 42g.
Update: the opening of the Mark II version is exactly the same as that of the Mark I version. I measured the weight to be slightly lower at 39g. This new version also ships with an USB-C Dock that allows to update the adapter’s firmware in case there are compatibility issues with future cameras.

Conclusion
I have been waiting for this for a long time and I wish it had been available sooner as it would have made my life reviewing lenses so much easier.
I don’t have any real complaints this time – except for the vignetting with the obscure MS-Optics 135mm 2.4 – and I usually don’t say this, but: if you are using M-mount lenses with 28/35/50/75/90/135 mm – or you are using 16/18/21/24 mm lenses and don’t mind to code them yourself – get one of these adapters.

Update: the MK II adapter has some useful improvements, the price stayed the same and I also like its all black color. In the TTArtisan shop it already replaced the MKI version.
Now that we already have the USB-C dock for firmware updates I (again) pitched the idea to TTArtisan to offer a software that allows you to map different unique Exif data to the 6 focal length settings on the wheel to support all kinds of lenses. Unfortunately there is no plan to offer such a software at this point. If you also think this would be useful please consider telling them on their Facebook or Instagram account. If we are enough maybe we can make it happen.
You can already order the improved MKII version from the official TTArtisan shop or from ebay.com for ~$75 (affiliate links)
Further Reading
My name is Bastian and I am your expert here when it comes to ultra wide angle lenses, super fast portrait lenses (ranging from a 50mm f/0.95 to a 200mm f/1.8) and I also have reviewed way too many 35mm lenses.
Don’t ask me anything about macro or wildlife shooting though.