The bokeh of MFT WAs: A test and an opinion poll

Started Oct 7, 2012 | Discussions thread
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Anders W
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The bokeh of MFT WAs: A test and an opinion poll
Oct 7, 2012

There have been quite a bit of discussion about the bokeh of various MFT lenses on the forum lately. To my surprise, the discussion has not only focused on longer FLs, where the quality of the background blur is of obvious importance, but also on the wide-angle end of the lens spectrum.

Personally, I haven't, up to this point in my 40 or so years of photographic life, paid a whole lot of attention to the OOF rendering of WA lenses for the simple reason that I rarely use them for the purpose of creating subject isolation by means of background blur. The primary reasons why I don't do so are twofold. First, you need to get pretty close (with all but the fastest WAs mounted on an FF camera) to create any background blur to speak of. And when you get to that point, you will get a fair amount of perspective distortion, which may be fine as a special effect at times but not something I opt for on a regular basis. Second, the wide FoV means that you will include a lot of background at low magnification, thereby significantly reducing the perceived amount of blurriness in comparison with what you would get with a longer FL used at the same subject magnification.

With such thoughts in mind, I asked the OP in a recent thread on the Olympus 17/2.8 why he found the OOF rendering of that lens so important. He replied that, in spite of shooting mostly subjects at close-to-infinity, he favored a style of landscape images that uses very subtle background defocus to give some "3D pop" without losing context. Fair enough. Although it is difficult to create much in the way of background blur with a lens like the 17/2.8, it might often be used in such a manner that at least parts of the background is outside the depth of field and thus unsharp although not manifestly blurred.

Even so, this answer left me somewhat puzzled. The reason is that I have never been able to perceive much of a quality difference between different lenses in the zone where their rendering is merely unsharp as opposed to clearly blurred. So I decided to make a little test of what my own eyes as well as those of others can actually distinguish when it comes to WA bokeh in this twilight zone.

Since, right now, I happen to have access to quite a few MFT WAs, including all Olympus and Panasonic WA primes and quite a few of the zooms with a WA component, I was able to make this test a rather encompassing one. Among the samples I post, you will thus find images produced by

Olympus 12/2

Panasonic 14/2.5

Olympus 17/2.8

Panasonic 20/1.7

Panasonic 7-14/4

Olympus 14-42/3.5-5.6 IIR

Panasonic 14-42/3.5-5.6 (not the X PZ version)

Panasonic 14-45/3.5-5.6

Although I will eventually reveal which image was produced by which lens, I will not do so before I have your comments on how you perceive the quality of their out-of-focus rendering. The reason is that I do not want to bias your perceptions so as to fit any preconceptions you might have about the various lenses. For now, I will instead ask three questions that I hope as many as possible will care to answer:

1. Do you see any significant differences between the sample images as far as the quality of the out-of-focus rendering is concerned?

2. If yes, which images are better and which are worse from this point of view?

3. If yes, in which way do you find some of them better and the others worse.

There is no requirement that you try to answer all three questions. If you answer no to the first of them, the other two are of course irrelevant. And if you answer yes to the first one, you are excused if you skip question three in case you find it difficult to specify exactly why you like the OOF rendering better in some cases than in others.

The sample images themselves will appear in a separate post right after this one!

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