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Sony A7II full frame with Canon EF 50mm f/1.8ii vs Olympus OM-D with PanaLeica D 25mm f/1.4 lens – real world comparison images

Monday, May 1st, 2017

These two lenses give a similar field of view – that of the “Standard lens” or 50mm in full frame terms.

I have posted similar DOF and background blurring comparisons for full frame 85mm f/1.8 vs Olympus 45mm f/1.8 and also full frame 85mm f/1.8 vs Olympus 75mm f/1.8 taken twice as far away.

This blog post is to demonstrate the slightly shallower depth of field (DOF) and more background blurring that a full frame camera can attain over a Micro Four Thirds camera – but does it make the image more aesthetic, and is the difference really worth losing all the fantastic benefits of Micro Four Thirds – smaller, lighter, less expensive kit, easier to take traveling, to social events and hiking, better weathersealing, better image stabilisation, touch screen AF, closest eye AF, more fun and versatility, and the list goes on.

Only you can decide if you really need to go shallower DOF – and of course on both cameras you can get even more shallow DOF – the full frame allows use of 50mm f/1.4 lenses (and even a Canon EF 50mm f/1.2L), while on the Olympus OM-D, you can use the wonderful superb Olympus micro ZD 25mm f/1.2 lens, and if you want, you can go to f/0.95 lenses but currently only in manual focus.

The Canon EF 50mm f/1.8 II lens is known as the plastic fantastic – perhaps one of the worst build quality of any modern AF lens, and a cheap price to match but it has reasonable optics – although, not the sharpest tool in the shed wide open, and has lots of vignetting on the Sony a7II, plus lots of coma aberration and the bokeh is quite busy and often annoying – but this comparison is just to show DOF and degree of background blurring at f/1.8. When used with the Sigma MC-11 EF-Sony lens adapter, you do get fairly fast AF but no Eye AF, BUT it is very frustrating to use as you must re-mount the lens every time the camera is turned off or goes to sleep, and sometimes AF is a very slow stuttering experience. For some reason, the Sony a7II under-exposes this lens at f/1.8 but not at f/2.8 – very strange indeed!

On a full frame camera such as the Sony A7II mirrorless camera, the Canon EF 50mm f/1.8 ii provides the user with a further 1.3 stops of shallow depth of field options when compared to an Olympus OM-D E-M1 II with the old, now discontinued, Panasonic leica D 25mm f/1.4 Four Thirds lens but will this really matter for most people and will the many benefits of the Olympus system outweigh the DOF benefits of the full frame system?

Note that this Four Thirds lens is one of the few that is compatible with CDAF, but for some reasons, AF is stutteringly slow on the Olympus OM-D E-M1 mark I but works fine on the mark II camera. This lens was replaced with a smaller, lighter, less expensive Micro Four Thirds version. Neither are weathersealed but the new Olympus mZD 25mm f/1.2 lens is.

Real world lens tests:

Let’s have a look at some jpg images straight from camera (just resized for web viewing) with both lenses wide open as I walked around some gardens yesterday, not really looking for great shots, but shots to show difference in depth of field and image quality between the two systems when taken from the same camera position.

The Panasonic 25mm f/1.4 lens is first then the Canon 50mm f/1.8 lens, both taken from same camera position:

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Note that the severe mechanical vignetting of the Canon EF 50mm f/1.8 II lens on the Sony a7 II is causing much more annoying “cat’s eye” shaped bokeh near the edges – note the sky highlights, as well as much darker corners. In addition, the longer aspect ratio of the full frame system makes it harder to exclude distracting skies in portrait orientation than it is with the wider Micro Four Thirds 4:3 aspect ratio – another reason I prefer Micro Four Thirds for portraiture.

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The greater blurring capability of the full frame is well demonstrated here but the near out of focus leaves on the right are far more annoying with their distracting bokeh compared to the less blurred but less distracting bokeh of the Panasonic image.

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When the focus point is farther away, the difference of the degree of background blurring becomes less between the lenses – as demonstrated with my previous posts.

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For this image, the 25mm lens gives adequate subject isolation and background blurring, and I think it has much nicer bokeh, plus if you look at the highlight area of the statues’ head, the cheap and nasty 50mm lens has much more flare, softer, less contrasty imagery – that’s one of the resons why you may want to pay more for a higher quality lens!

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Again the 25mm gives adequate background blurring and it is less busy – look at the branches of the birch – but this bokeh issue is not a full frame versus MFT issue but a lens design issue.

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The larger out of focus circles of the 50mm are actually much more distracting and annoying – sometimes the more background blurring is actually worse for aesthetics!

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Again the 25mm gives adequate background blurring and it is much less busy with nicer bokeh.

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This closer image of grapes, looks nicer with the 50mm lens to my eye as the much larger out of focus bubbles make it less busy.

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The 50mm lens here is giving too much background blurring making it hard to work out what is in the background which can work against the aesthetics by making the viewer work too hard – of course, the 50mm could have been closed down to f/2.8 to address this.

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The bridge looks busier on the 50mm lens – the 25mm to my eye is giving nicer bokeh and sufficient background blurring.

Moral of the story:

Just buying into a full frame system does not guarantee you nicer looking, shallower depth of field, more aesthetic bokeh – you do need to choose your lens carefully, and lens design is always a trade off between wide open sharpness vs wide open bokeh:

The superbly sharp, big, heavy, expensive, Sigma 50mm f/1.4 Art lens has busy, distracting bokeh – sort of defeats the purpose of having a shallow DOF lens.

The Canon EF 50mm f/1.2L lens has buttery smooth bokeh but is soft (not that sharp) wide open with lots of aberrations.

The Canon EF 50mm f/1.4 lens is soft wide open with lots of aberrations and often busy bokeh but at least it is relatively small and inexpensive.

The Sony FE CZ 55mm f/1.8 ZA is sharp across the frame, relatively compact but has busy onion ring bokeh and costs $AU1150.

The Sony FE 50mm f/1.4 ZA has nice bokeh and is sharp in the centre wide open but is soft half way to edges and will set you back $AU2250!

See also my comparison table of the high end 50mm AF lenses for a Sony full frame.

And here we have the full frame conundrum – which is the lens that suits your needs best and can you afford the cost and weight?

If you are going to have stop it down to f/1.8 or more for adequate image quality or depth of field, then perhaps you are not really gaining much over an Olympus 25mm f/1.2  lens which is weathersealed, compact, relatively light, has almost zero aberrations and minimal distortion, probably better edge-to-edge sharpness wide open, can focus twice as close, has a lovely manual focus clutch, and has by far the best image stabilisation of 5EV 5 axis IS when used with Olympus OM-D cameras, which also allow fast, accurate AF almost anywhere in the frame (not just near the middle and which can be activated rapidly by using the touch screen or even the touch of the Live View screen on a wifi tethered smartphone) and with ability to accurately AF on the closest eye – just awesome! And that’s not all – on the E-M1II you get continuous AF at 18fps and silent shutter, not to mention the unique Olympus Live Composite mode for doing star trails, car headlights, etc at night, and for static scenes with tripod, the ability to shoot 50mp Hi Res shots.

ps… I didn’t do this comparison with the Olympus 25mm f/1.2  lens as I don’t own one ….. yet! :)

In the end, do you really need the extra shallow DOF that full frame affords when you are giving up so much to have it?

Sony A7II full frame with Canon EF 85mm f/1.8 vs Olympus OM-D with Olympus 75mm f/1.8 lens – real world comparison images

Monday, April 24th, 2017

In an earlier blog post, I compared the Sony A7II full frame with Canon EF 85mm f/1.8 vs Olympus OM-D with Olympus 45mm f/1.8 lens in terms of how they render the background wide open at f/1.8 at approximately the SAME subject distance and approximately the same field of view. The full frame kit allows 2 stops more shallow depth of field, but for most situations, the ability to blur the background with the 45mm lens is adequate, and it does so at a much smaller size.

In this post, I tackle the photographic problem slightly differently as I tried to maintain the same subject magnification by shooting the 75mm lens twice as far away from the subject as the Canon EF 85mm lens as the 2x crop factor of Micro Four Thirds means the Olympus 75mm lens actually has the field of view of a 150mm lens in full frame terms.

These are two of the sharpest wide aperture “consumer” lenses from each manufacturer – unfortunately, neither are weather-sealed.

Thus when shooting both lenses wide open at f/1.8 at same subject magnification as outlined, one can expect for the Olympus 75mm lens, the background field of view will be narrower and more compressed (which I prefer as most Australian forest backgrounds tend to be busy, chaotic and distracting, and one can better avoid having distracting bright skies in the frame, so less background for me is better, even though it is not as blurry).

Had I shot with the background at infinity, the DOF calculations indicate that the background would be just as blurry, but when the background is quite close to the subject as in these images, the full frame does give more blurry images – but at times too blurry (although this can be addressed by stopping the aperture down but then may need to increase ISO by 2 EV if you cannot afford to have a slower shutter speed, and then the benefits of full frame are largely lost).

One big difference between the two is the far better close up magnification obtainable with the Olympus mZD 75mm lens as both have close focus of around 0.85m but the Olympus does this with twice the telephoto effect giving twice the macro.

In addition, I feel the Olympus OM-D cameras render the greens in a more pleasing way than the Sony a7II, and of course, the Olympus camera has a 4:3 aspect ratio which I think works better for portraits, while the Sony has the old, historic, narrow 3:2 ratio.

The Canon EF 85mm f/1.8 lens is a highly regarded “portrait” lens, often regarded as one of the best Canon lenses which is not a Pro L lens. It is sharp but does have some CA issues wide open. When used with the Sigma MC-11 EF-Sony lens adapter, you do get fairly fast AF but no Eye AF.

On a full frame camera such as the Sony A7II mirrorless camera, the Canon EF 85mm f/1.8 provides the user with shallow depth of field options when compared to the slightly smaller (58mm filter vs 58mm filter), lighter (305g vs 400g) Olympus micro ZD 75mm f/1.8 lens but will this really matter for most people and will the many benefits of the Olympus system outweigh the DOF benefits of the full frame system?

The Olympus mZD 75mm f/1.8 lens is regarded as one of the best lenses ever made optically and is one of my all time favorite lenses for people photography and also shallow DOF work on Olympus cameras. Unlike the 85mm lens it is optimised for mirrorless cameras and their CDAF system and thus you can have fairly fast, accurate face detection autofocus on the subject’s closest eye (if they are not moving much), which is an awesome feature indeed – this is not possible with the Canon lens.

The Olympus lens has 5EV image stabilisation thanks to the Olympus OM-D E-M1, while the Canon lens gains around 2-3 EV IS thanks to the Sony a7II (it would have none if used on a Canon dSLR).

Real world lens tests:

Let’s have a look at some images straight from camera (just resized for web viewing) with both lenses at f/1.8 as I walked around an oak forest yesterday, not really looking for great shots, but shots to show difference in depth of field and image quality between the two systems when taken from the same camera position.

The Olympus is first then the Canon, all taken at f/1.8, base ISO, with auto WB unless specified, and none had any filters applied to the lenses – both had lens hoods attached:

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I much prefer the Olympus version of the above two, gives better context and I personally find the bokeh of the Canon one a bit annoying because we have lost the definition of the trees too much leaving distracting vertical lines.

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The above was taken with “Shady” white balance.

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The following two show that if the subject distance is substantially less than the background distance, then the degree of background blurring becomes more similar with the two lenses.

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The following two were taken not with the same imagery, but I have added them anyway.

The Olympus  was with WB set to “Shady” but came out too warm – I should have taken a custom WB with a grey target to get the best rendition here.

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The foreground bokeh of this last Canon EF 85mm lens image is very distracting and busy and in fact is so annoying I would be forced to crop it out.

Each lens renders images differently even though I have tried to control subject magnification – both have nice bokeh in most cases, but you do get quite different images – sometimes in favor of the Olympus (thanks to double the background compression), sometimes in favor of the Canon 85mm (thanks to more blurring of a nearby background).

There is no “RIGHT” camera / lens combination that will suit every image – you as the photography have the decision to make as to which tool is needed – assuming you have the tools with you.

But in the end, if you had not seen the full frame imagery, most would be very happy with the degree of background blurring of the Olympus lens – it has how you use it that will determine the success of your photography.

Here is what the Olympus 75mm lens can achieve in outdoor available light portraiture:

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Sony A7II full frame with Canon EF 85mm f/1.8 vs Olympus OM-D with Olympus 45mm f/1.8 lens – real world comparison images

Sunday, April 16th, 2017

Similar field of view and both have nice bokeh but are very different sizes and ergonomics.

I have posted similar DOF and background blurring comparisons for full frame 50mm f/1.8 vs Olympus 25mm f/1.4 and also full frame 85mm f/1.8 vs Olympus 75mm f/1.8 taken twice as far away.

The Canon EF 85mm f/1.8 lens is a highly regarded “portrait” lens, often regarded as one of the best Canon lenses which is not a Pro L lens. It is sharp but does have some CA issues wide open. When used with the Sigma MC-11 EF-Sony lens adapter, you do get fairly fast AF but no Eye AF.

On a full frame camera such as the Sony A7II mirrorless camera, the Canon EF 85mm f/1.8 provides the user with a further 2 stops of shallow depth of field options when compared to the much smaller (37mm filter vs 58mm filter), lighter (115g vs 400g), and similarly priced Olympus micro ZD 45mm f/1.8 lens but will this really matter for most people and will the many benefits of the Olympus system outweigh the DOF benefits of the full frame system?

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Real world lens tests:

Let’s have a look at some images straight from camera (just resized for web viewing) with both lenses at f/1.8 as I walked around some gardens yesterday, not really looking for great shots, but shots to show difference in depth of field and image quality between the two systems when taken from the same camera position.

The Olympus is first then the Canon:

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The following Olympus image I accidentally shot at f/2.2 instead of f/1.8:

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And I shot this Canon image at f/3.5:

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While this Canon image was shot at f/1.8:

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But what about portraits?

A group of young ladies asked if I could take a photo of them with their iPhone – for some reason this is an incredibly frequent happening for me – perhaps they know they can outrun me if I take off with their phone! One of the ladies became excited when she saw I had her “dream” camera – the Sony a7II in my hands and wanted to see what it can do with a portrait so I did some very rough comparisons of the two cameras (NOT the iPhone!):

Olympus 45mm:

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Canon 85mm from a touch further away.

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I tried to explain the differences, but what really got them excited was when I showed them they I could just touch the rear screen of the Olympus and instantly, it snapped it accurate AF on the subject I touched and took the candid shot:

Olympus image shot using the touch AF on rear of screen:

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Conclusion:

There is far more to photography than the technical aspects – photography should be about fun, affordability and inspiring exploration, and above all not be too cumbersome to carry around, and on these points the Olympus kit wins hands down!

The Sony’s poor ergonomics, lack of touch screen AF, no eye detect AF with the Canon lens, only 2 stops IS vs 5 stops in the Olympus, and its propensity to not turn itself off were also big factors in favor of the Olympus OM-D camera.

And, having just played with an entry level Canon EOS 1300D dSLR, it’s poor ergonomics, lack of features, very poor, dim and small viewfinder – I can’t understand why people would not just buy a much better built, weathersealed, very versatile and good looking second hand Olympus OM-D E-M5 camera for a similar price with similar image quality but much better image stabilisation, AF speed and accuracy as well as better dedicated lenses.

I can easily understand why Sony have jumped to 2nd place on full frame camera sales in the USA – leap frogging over Nikon – this would have been unfathomable even 5 years ago – but Canon and Nikon persist with their dinosaur mentality in camera and lens design – and I can understand why the traditional studio or landscape pro photographers who used their systems are jumping to medium format or to Sony.

I can understand why Canon and Nikon are reluctant to introduce functional mirrorless full frame cameras – it exposes their faithful who own very expensive dSLR lenses to the same fate that Olympus Four Thirds users have suffered when Micro Four Thirds was introduced – the realisation that all their existing AF lenses are no longer suitable for the new age of mirrorless CDAF technology and need to be replaced with CDAF-optimised AF stepping motors which will seriously devalue their lens collection – fortunately for me, most of my Canon pro lenses are manual focus tilt-shift lenses so this won’t impact me much when it happens.

In the meantime, we can buy Sony full frame mirrorless cameras with in camera image stabilisation with Eye AF capability, etc and ability to use Canon lenses and flashes even in remote TTL mode – so why buy a Canon dSLR?

In the end, you have to ask yourself if the full frame imagery is really worth it – and in some situations it may be – but if I am needing shallower DOF with the Olympus, I resort to the Olympus mZD 75mm f/1.8 lens which is my go to lens in this situation – of course if you have the money you could also go for the Panasonic Leica DG 42.4mm f/1.2 lens.

 

 

 

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

Sunday, 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.

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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:

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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.

 Conclusion:

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.