Welcoming TechArt Leica-sony AF adapter LM-EA7 (part 1)







Is there any practical way to change manual lens to auto-focus for super duper latest digital camera?  

    10 years ago: “What a glorious fanciful dream?”

     5 years ago: “Haha, wake up, man….”

     Now: “Yeap, here you are.”

TechArt adapter is a device that turns a manual lens to auto-focus lens.

So suddenly, dream comes true !!



Evolution of the adapter

Until the advent of the mirrorless cameras, Canon EF system used to be a platform of crossbreeding which adapt & use

manual lens with digital body. Canon EF camera has relatively short flange back distance (from the lens mount to the sensor,

fD = 44mm) and large lens mount diameter, thus accept other makers’ lenses, e.g. Nikon F, M42 etc

through piece of thin metal plate. That’s starting point of adapter business.

Then, mirrorless camera arrived. Since Sony’s E-mount flange-back is extremely short (fD=18mm) and basic specifications

of the E-mount open to public (3rd party), new market is created, called ‘AUTO FOCUS crossbreeding’.

Adapter is no longer piece of metal plate or cylinder. It transmits signal from body to lens & vice versa with firmware to 

translate one language (Sony signal) to another (Canon signal).

Simple adapter

It is a cylinder at one end has Sony E-mount and the other end different makers’ mount. The length of the adapter

determined by the difference of fD between the two models. Since Sony E mount has 18mm distance in flange,

Nikon adapter is manufactured in 28.5mm (=46.5-18) and Canon FD lens adapter is 24mm (=42-18) etc… 

Even DIY can be easily done if tooling to cut and grind metal piece available.


Helicoids adapter

Similar to Simple adapter at a glance, but Helicoids adapter can be elongated and retracted as lens’ focus ring does.

Just as inserting a close up tube, it makes possible to take close-up photo below the minimum focal distance of the lens.

For most DSLR lenses helicoids may not be much attractive because their close focus range is already close enough

(45cm) for most of cases. Or if any photographer serious about close up & macro photography, he or she will choose

macro lens anyway instead of bothering close range of standard lens. 

But it is whole different matter for rangefinder lenses.





   Canon FD 55mm f1.2 SSC lens + FD to LM adapter + LM to Sony helicoid adapter

Leica M mount helicoids adapter

The Leica M series is the rangefinder camera with 27.8mm flange-back distance. Typical SLR camera has 42 to 48mm  

distance, so not possible to adapter Leica M lens (or any other RF lenses) to digital camera, until the Mirrorless came.

Sony A7 series is full-frame mirrorless camera which takes Leica M lenses with 9.8mm thick adapter.

(Remember? Sony E has 18mm fD, while Leica M has 27.8mm fD)

Apart from its price, the most annoying fact of M lens is its closest focus is not close enough.

For example, standard lens Summicron’s minimum focusing distance is 1m. It is hard to take shot for the opposite party

around table or an object on a table. In case the opposite party is your wife who was reluctantly convinced you spending

a small fortune to buy a German stuff, ‘Leica…whatever’ she will challenge back definitely when you are not able to

take photo at a Cafe with her. So better be prepared. 

Helicoids adapter will shorten Summicron’s minimum focus distance down to 40cm respectively.




   From left : Leica M helicoids adapter, TechArt LM-EA7, Olympus 4cm f2.8, Summitar 5cm f2.0

Sony-Canon auto focus lens adapter

We can use the AF signal coming from Sony body to drive Canon AF lenses.

Of course, presumably should know about AF algorithms for both Sony and Canon models. Then, how?

Usually called politely as ‘reverse engineering’ or sometimes called ‘hacking’ bluntly….

Sony itself sells two adapters, LA-E3 & LA-E4. The majority of the autofocus adapter hacked LA-E3 adapter

to figure out AF algorithm. LA-E3, as an adapter, signal is relatively simple & strait forward.

Thus, attaching such an adapter recognized as LA-E3 adapter by Sony body.

Last year Chinese firm TechArt released the EOS NEX III Adapter hacked the Sony lens instead of LA-E3.

Lens / Body signal is much complicated, but it also support more advanced functions which only available for

genuine Sony lenses. When TechArt EOS NEX III Adapter attached, Sony body recognizes it as ‘the lens’.

After initial sensation of EOS NEX III and following backfire of ‘poor reliability’ of actual products, a major player

joined in this battle. Sigma released MC-11 adapter which is recognizable as a lens early in this year.


   TechArt EOS NEX III adapter & Canon Samuel (35/1.4) and baby-Mantou (85/1.8) lenses

   By the way, why only Canon lens AF adapter existing?

   In fact, Canon was (is?) a winner in digital era, especially DSLR period. Canon lenses sold far more than any competitors.

   For any business person who want to take a pie in this market, he / she should take first step to Canon lens.

   No other way. Period.

Leica M mount Auto Focus (AF) adapter

Now, sudden breakthrough taken place, finally we have a product was only dream couple of years ago.

As said, TechArt engineers mastered how Sony body and Canon lens combination work. This time, they build

Leica M helicoids adapter which is not manually work but using AF signal from Sony body. It operates a stepping motor

with AF drive signal from Sony A7 II (PDAF protocol) to be the Leica M mount AF adapter.

Handy thing is there are plenty of additional adapter to Leica M already existing in the market, for example Nikon F to Leica M,

Contax C/Y to Leica M adapter & many others. So literally it makes virtually all lenses produced at last century usable in

Auto Focus mode. 

Even something in displayed at Museum like 19C Petzval lens can be usable in AF.





TechArt box is fixed to the inner magnet. Opening the lid will open up the box.

   Inscription ‘KPLIANG‘ is suspected to be in handwritten name of the developer(?).

   LIANG is Chinese surname & KP is thought to be an abbreviation of the name.

   (Hi, TechArt guys, please let me know if my guess is NOT the case)











   The stepping motor and control circuit located in the bulge of the lower adapter.

   Surprisingly, the adapter is not sealed at all, so user looks inside through large opening shown above picture. 

   This opening is not because of carelessness. It is necessary for breathing when helicoid mechanism is moving

   forward or backward. On the other hand, it will be a gate to collect dust and debris in long-term, cause of 

   the malfunction of the motor, gearbox or control circuit. We’ll see …

Mechanical build quality

Unlike the low-cost lens adapter frequently suffered excessive play, TechArt fits tightly without play or requiring

over force. It tells the adapter manufactured in very precision machining in excellent quality control.

Plastic covering is just ordinary, nothing to blame but nothing to appeal for precision build quality. 

Now I can not complaint because there is no other context of similar products by other companies

for comparision.


Here is several examples of lens + adapter combination



   Left : Leica M3 with Summicron DR (only M lens not fit into TechArt adapter)

   Right : sony A7 II with Summicron rigid





   Looks almost identical with Summaron 3.5cm f3.5 lens, but this is Olympus 4cm f2.8


   It has half stop birghter than f3.5 Summaron. 

   Yes, there is f2.8 summaron too…. but hard to agree with its price.


   Compact and unique profile


   I think the Summitar is the most underated among Leica LTM lenses.


   Collapsible lenses can be collapsed at Sony A7 body.

   (Not at crop body)


   Summicron rigid has longest barrel among Leica standard lenses


Lens made in the last century

In fact, the modern lenses are too good to differentiate each other. With sophisticated computer design and computer

based production machines, lenses perform what designed for. Only constraint is financial side, who will be target

customers and how much ask for payment…

The manual lenses from old days have flaws here and there. But in fact, those flaws make their personality and charm.

They are not in the same league of Resolution or MTF as of nowadays. It is taste of photographers to choose and

use them who want to ‘express’ something instead of ‘record’ highest possible resolutions.

In addition, except that some items sought after by collectors, price is attractive & fairly affordable still.

(And now, we are talking about using them in AF…)






   Carl Zeiss Planar 85mm f1.4 HFT (Rolleiflex version)








   Meyer Optik Trioplan-N 100mm f2.8




** terms described in here qualitative manner, e.g. cheap, affordable, excellent … it lacks of universal metrics

    quantitative number for comparison. It is not my intention to drill down details for manual lenses in here. 

    I want to keep it short & in person and discuss details in another article.  




    Leica LTM screw mount lenses: from 50s to early 60s. typical classic lens characteristics (low contrast, mid-high

                          resolution), cheap price and reasonable performance

    Leica M-mount lenses: the lens of 60s to 80s. price getting higher but still within reasonable range, excellent

                         performance. After late 80s, price skyrocketed, well beyond ordinary hobbyist or semi-professionals’

                         budget unless you take re-selling price into account. Should be picky though…  

    Contarex CRX lens: high-end premium lenses from 1960s, the price is somewhat too high due to collectors interest.

                         Probably its selling price be the same or even higher in future…

    Rolleiflex QBM lens: 60 – 80s of the lens, good performance at an affordable price.

                          Rollei 35mm lens has mixed origins (Germany, Singapore & Japan) and no practical adapter available

                          when Canon EF was interbreeding platform, thus its prices is pretty low. Need to be aware and

                          knowledgeable about difference of origins & their price ranges.

    Contax RF, Kiev, Nikon-S rangefinder lenses; the lens from classic 40- 60’s era. It was abandoned model for

                          crossbreeding for a long time, so was dirt cheap. Now Contax RF and Nikon-S lens price sharply

                          raised due to collector’s interest and affordable adapters available in the market.

                          On the other hand, Kiev lens remains the low profile and price tag. They are available in enormous

                          quantities & sparse production quality from Eastern bloc.


Providing brief introduction is not easy due to variety of manual lenses, type, origin, character and history.

F1.2 lenses from SLR is something worth to mention at first for consideration, e.g. Nikon F 55mm, Canon 55mm SSC,
Minolta 58mm PG & Konica 57mm AR. They are much more useful in AF + mirrorless combination than their original
SLR platform.
We can search endlessly German makers, Enna, Schacht, Steinheil, Meyer, Isco (yes, I assume you already
finished Carl Zeiss, Schneider and Rodenstock side) and continue Japanese Nikon, Canon, Pentax, Minolta, Olumpus..
etc etc etc

It is real amazing we can use all of them in AF from now on.






   Carl Zeiss Biogon 35mm f2.8

   Sharp and contrasty but price jumped too high recently








   55mm f1.2 lenses from Canon (left) and Nikon (right)



King of King of King  !!!

Among these and other manual lens, there is top one. Only one.

The most ambitious, hardcore competition winner of all time is Canon 50mm f0.95 lens.

It is not surprising its aperture is beyond 1, f0.95 but also was debuted in 1962….

Until now 2016, no other one surpass its legend yet. 

If mentioned equally bright lens, Leica 50mm f0.95 is…

which came to market after 30+ years later and with 5 digit US Dollar price tag..









   Comparision Leica m3 with Summicron f2.0 with Canon 7 with f0.95








F0.95 Canon lens can be converted into Leica M mount & usable in Leica digital body.

However the depth of field is razor thin in wide open, so camera RF mechanism has to be aligned

precisely & accordingly. 

Mirrorless camera to magnify the image at sensor directly is the best platform for this lens at this moment. 

To be honest, I cannot imagine how users can shoot it with RF film camera without stop down 2-3 steps. 

There was no way to check and ensure ultra thin depth of focus lay where photographer wanted (or hoped).

There is dedicated adapter for the Sony A7 body to attach this lens, and in case the lens modified to

Leica M mount, helicoids adapter is good enough to cross border.

   Unfortunately TechArt LM-EA7 adapter is not usable for this lens.

   The lens barrel is too fat, bulge from the bottom part of the adapter hinders proper attachment ….

   Too bad news…




   From left: Canon f0.95, Elmar f3.5 & Summitar f2.0


Continue 2nd part,

Using the adapter, cautions, advantage and limitation






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