Hands on review of Metabones Canon EF lens to Micro Four Thirds Olympus OM-D “T Smart Adapter” with the Canon EF 135mm f/2L lens

Written by Gary on April 24th, 2016

Readers will be well aware that not only do I love my Micro Four Thirds gear but I also own quite a few expensive Canon pro lenses so it made some sense for me to buy the Metabones “T Smart Adapter” (MB_EF-m43-BT2) when one came up second hand on Ebay recently.


I have actually been wanting to buy the Metabones Speed Booster adapter which also has internal optics giving a focal reducer effect of 0.72x (and 1 stop aperture), but in Australia, these are ridiculously expensive at around $A1200 if you can find a store with one in stock – at that price you would be better off buying a Canon mirrorless camera with sensor-based IS and fast AF – except Canon don’t make any such camera.

A bit of background on adapting Canon EF lenses to Micro Four Thirds

One has always been able to buy cheap Chinese adapters to mount Canon EF lenses BUT these do not allow aperture control (Canon EF lenses do not have an aperture ring to manually change the aperture), do not support OIS, nor AF and do not send EXIF data to the camera.

This means that when using these adapters, one must manually dial in to Olympus OM-D cameras the actual focal length so the camera’s IS system is optimised, and if one wants to use a different aperture, one needs to dismount the lens, attach to a Canon camera, set the desired aperture, press the DOF preview button whilst dismounting lens, then re-mount on the Olympus camera – not a wonderful idea but it does work.

Recently, adapters have been produced with electronic communication between the camera and lens which provides aperture control, OIS support, EXIF data (camera automatically detects focal length for IS), and variable capabilities of AF.

One such lens is the Metabones T Smart Adapter, and this lovely adapter is firmware upgradeable via its built-in USB port, and Metabones have recently updated the firmware to add phase detect AF compatibility with the Olympus OM-D E-M1 for specified Canon EF lenses (BUT NOT the Canon EF 135mm f/2.0L lens!) as well as improved CDAF autofocus on other Micro Four Thirds cameras. This adapter also has a tripod mount for use when using larger lenses.

Optical image stabilisation in the lens is functional on Olympus cameras if the OIS switch on the lens is ON and the camera IS is OFF – although you probably would not want to do this as the Olympus IS is going to be much better than Canon’s OIS, and as yet, support for DUAL IS is not available.

Autofocus is best used in single AF point mode (indeed multi-point AF modes are not supported), and in S-AF (C-AF and C-AF Tracking modes are not supported as yet even on the E-M1), in addition, you may wish to use the Vivid Picture mode as this improves contrast detection AF.

I upgraded the Metabones adapter’s firmware to the latest version which is V2.2 released on April 2016.

First, the Olympus OM-D E-M1 AF quirk:

The Olympus OM-D E-M1 camera is different to all other Olympus mirrorless cameras in that it is the only one with a sensor that has on-sensor phase detect AF sites which makes this camera far better at autofocus on faster moving subjects and on lenses which are not optimised for CDAF such as most Four Thirds lenses.

When using CDAF-compatible lenses the E-M1 uses a hybrid of both phase detect AF and CDAF algorithms to provide ultra fast AF.

When using lenses the E-M1 does not detect as being CDAF compatible, CDAF is apparently disabled and the camera relies solely upon phase detect AF which raises a paradox for this Metabones adapter – phase detect AF will be the default mode on the E-M1 BUT, if Metabones has not optimised the adapter for a specific lens (eg. the Canon EF 135mm f/2.0L lens), AF performance will be terrible on the E-M1 and MUCH, MUCH worse than on the other Olympus cameras which will at least use CDAF mode!

Please Olympus, add a setting where the advanced user can select CDAF mode only – this also creates a difference in the way the E-M1 handles the Panasonic Leica-D 25mm f/1.4 lens which is CDAF compatible but not recognised by the E-M1 as being so.

Some quick AF tests:

When using Canon lenses listed by Metabones as compatible (eg. Canon EF 24-105mm f/4L IS and 50mm f/1.8), AF on the E-M1 is quite good and snappy, although not as fast as using Micro Four Thirds lenses but perhaps around the speed of using Four Thirds lenses on these cameras.

When using Canon lenses including the 135mm f/2.0L lens on Olympus OM-D E-M5 which does not have phase detect AF, AF is relatively fast IF the subject is contrasty, in good light and almost in focus, otherwise it will hunt quite a bit, much like when using Four Thirds lenses.

When using face detect closest eye CDAF with the 135mm lens on the E-M5 for close portraits at 2m, the camera appeared to select the face and focus but some of my images were not in focus on the eye suggesting this may not actually be working all the time – I will need to test this further to make sure it wasn’t just shallow DOF and subject-photographer movement causing the issue.

Why bother using Canon lenses on Micro Four Thirds?

Now this is an excellent question given that Olympus and Panasonic have an excellent range of dedicated lenses with silent, fast AF and which are much smaller and lighter, and often with better optics than the Canon lenses.

However, if you have some niche lenses like I have (the Canon TS-E 17mm f/4, 45mm f/2.8 and 90mm f/2.8 tilt-shift lenses) then aperture control is very handy indeed. Note that you don’t really need tilt-shift lenses for the Olympus cameras as you can buy adapters which convert full frame legacy lenses into tilt-shift lenses, nevertheless, if you already own these nice canon lenses then you may as well use them.

I would not have need for the Canon 50mm f/1.8 as the Olympus 45mm f/1.8 is better and has fast AF.

I would not have need for the Canon 85mm f/1.8 as the Olympus 75mm f/1.8 is better and has fast AF.

I would not have need for the Canon 24-105mm f/4 IS as the Olympus 40-150mm f/2.8 is wider aperture and gives more telephoto reach and has fast AF.

But what about the Canon EF 135mm f/2.0L lens?

I used to love the shallow DOF and lovely bokeh of the Canon EF 135mm f/2L USM lens on my Canon 1D Mark III camera, but when I discovered I could achieve almost the same imagery but with far more accurate focus and microcontrast using the Olympus OM-D with a Olympus mZD 75mm f/1.8 or Rokinon/Samyang 85mm f/1.4 lens, my Canon lens has remained idle in my cupboard along with my big, heavy, pro expensive Canon 1D dSLR.

I have the Olympus mZD 40-150mm f/2.8 lens which is far more versatile, much faster focusing, with much less internal flare and better micro contrast than the Canon EF 135mm f/2 lens for much the same size and weight, but the Canon has one significant advantage which may be valuable to those who want even smoother bokeh and shallower depth of field than what the Olympus zoom lens can provide.

Of course, Olympus users could buy the superb Olympus ZD 150mm f/2.0 Super pro lens to get even shallower DOF and smoother bokeh but this costs thousands of dollars and is big and heavy, and like the Canon lens is not CDAF optimised.

Using the Canon EF 135mm f/2L lens on the Olympus OM-D at ISO 200 almost gives the equivalent field of view, depth of field, exposures and image quality as when using a Canon EF 300mm f/4L IS lens on a full frame Canon dSLR body but at much less weight and size, and with better manual focus support, but AF for moving subjects will not be possible with the current firmware.

I have used the Canon 135mm lens to great benefit in shooting comets with the Olympus camera attached to a guided equatorial telescope, and for this purpose a cheap Chinese adapter is all that is needed:


To demonstrate the differences in how the Olympus zoom lens paints images at 135mm compared to the Canon EF 135mm f/2.0, I shot some comparison images at the same position and roughly similar settings and compositions. The Canon lens was shot on the E-M5 while the Olympus lens was shot using the E-M1. No polarising or other filter was used. Picture mode was vivid on each and all were processed to web size from RAW files via Olympus Viewer software without any post-processing otherwise.

Olympus 40-150mm

Above, the Olympus mZD 40-150mm f/2.8 at f/2.8 with lens hood into the afternoon sun

Canon 135mm

Above, the Canon EF 135mm f/2L USM at f/2.0 with lens hood showing more internal flare, less microcontrast, but thanks to the f/2.0 aperture, larger out of focus highlights and shallower depth of field.

and … a closer subject with out of focus foreground in bottom left:

Olympus 40-150mm

Above, the Olympus mZD 40-150mm f/2.8 at f/2.8 with lens hood into the afternoon sun

Canon 135mm

Above, the Canon EF 135mm f/2L USM at f/2.0 with lens hood again showing more internal flare, less microcontrast, but thanks to the f/2.0 aperture, larger, smoother out of focus highlights and shallower depth of field.

Canon 135mm

Above, the Canon EF 135mm f/2L USM at f/2.8 to show that at equivalent apertures degree of out of focus blurring is similar but with the Canon you now see the shape of the diaphragm blades while in the Olympus image the out of focus highlights at the edges are oval due to vignetting.


If you have Canon lenses then the Metabones T Smart adapter or the Speed Booster adapter may be reasonable to give you more photographic options, just don’t expect miracles with AF speed just yet although even with the 135mm lens on the E-M5 AF is usable if you have a static subject and are patient.

For most people, the Olympus mZD 40-150mm f/2.8 lens will give adequate DOF and be far more versatile and with faster AF that they will not bother using the Canon 135mm f/2 lens, but some of us do like to have access to the effects of using a f/2.0 lens even if the result is relatively subtle and probably only photographers who are aware of bokeh will notice the difference.

Of course, with the Speed Booster adapter, the 135mm f/2 lens becomes 100mm f/1.4 which gives similar field of view and depth of field of a 200mm f/2.8 lens on a full frame camera, and this does make it attractive although the Speed Booster is almost twice the price of the T Smart Adapter.


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