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, 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 at similar subject magnification (ie. the Olympus ones around twice as far from the subject given the 2x crop factor).
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:
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.
The above was taken with “Shady” white balance.
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.
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 white balance with a grey target to get the best rendition here.
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 photographer has 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: