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Olympus M.Zuiko 17mm f/1.2 PRO - Review / Test Report - Analysis |
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Lens Reviews -
(Micro-)Four-Thirds
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Page 2 of 3
Distortion
Image distortions are generally nothing Micro-Four-Thirds users have to worry about because these are corrected under the hood. This also applies to the Olympus M.Zuiko 17mm f/1.2 PRO which only shows a negligible barrel distortion. While JPGs or Photoshop/Lightroom will not show you the original distortion characteristic of the lens, CaptureOne still does and it reveals a native barrel distortion of ~3.4%. While it is quite heavy, it's a least no excessive.
Vignetting
Image auto-correction does also make a difference when it comes to vignetting. Unsurprisingly, the original vignetting is quite high at 1.2EV (f-stops) at maximum aperture. Stopping down to f/2 reduces the light falloff quite a bit and it's barely visible from f/2.8 onward. Autocorrection has, of course, the highest impact at f/1.2 with a 0.7EV reduction. Beyond, it doesn't need to work quite as hard keeping the issue at bay.
That all being said - compared to full format cameras, this is all next to nothing even at f/1.2.
MTF (resolution)
The resolution of the Olympus M.Zuiko 17mm f/1.2 PRO isn't quite on the same level as on the 45mm f/1.2 PRO. The center is impressively sharp at f/1.2 already but the borders/corners are "only" good to very good - which is certainly commendable at this setting. Stopping down improves the center to an excellent resolution at f/1.6 and to biting sharpness at f/2 but the outer image field improves only marginally. Diffraction effects set in beyond f/2 but they aren't overly noticeable until f/8 really.
The field curvature is low. The centering quality of the tested sample was Ok with a slightly tilted focus plane.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness.
If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
Lateral CAs are well-controlled at around 0.4px on the average at the image borders.
Bokeh
Olympus is emphasizing the lens's ability to produced a "feathered" bokeh. This is referring to the way out-of-focus highlights are rendered. If those highlights are "feathered", the brightness of the highlight discs fades towards the edges of the discs. As you can see below the highlights have indeed a very fuzzy edge transition. The inner zone of the discs is also very smooth.
The circular shape of the highlights deteriorates the more you move to the image corners and the Olympus lens is no exception here (technically this is a mechanical vignetting effect from the lens opening). Still, the results remain pleasing at f/1.2. Stopping down transforms the disc shape but it takes till at least f/2.8 till the discs are also circular in the outer image field. Please note that this is a normal effect.
Note: You may spot some double-haloed highlights in the f/1.2 sample below - these relate to the combination of the wide-angle character of the lens and the shape of photodiodes used as a light source.
The general rendition of out-of-focus elements in the focus transition zones is also very silky. Once again - top marks for Olympus here!
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