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Samyang AF 50mm f/1.4 FE - Review / Test Report - Analysis |
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Lens Reviews -
Sony Alpha (Full Format)
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Page 2 of 3
Distortion
The Samyang AF 50mm f/1.4 FE produces a very minimal barrel distortion (0.2%) in RAW mode. With active image auto-correction, the remaining traces are gone.
Vignetting
Vignetting is always a bit of an issue with fast lenses mounted on full format camera and the Samyang lens is no exception here. Its native light falloff is quite heavy at just over 2EV (f-stops) at f/1.4 and it's still visible at f/2.
This is nothing to worry about with image auto-correction, of course (other than increased corner noise). In this case, the vignetting is already moderate at fully-open aperture and a non-issue beyond.
This is, of course, very different in uncorrected mode. At f/1.4 the vignetting is rather massive in this case (~2.8EV) and still very noticeable at f/2. The situation eases at f/2.8 and it's good beyond.
MTF (resolution)
Following the recent review of its cousin - the Samyang AF 35mm f/1.4 FE - we hoped that the Samyang AF 50mm f/1.4 FE would have a similar (excellent) characteristic but this is not the case.
While the dead center quality is very good at f/1.4, the resolution drops dramatically towards the outer image field. In fact, the borders/corners are dismal. The center zone improves substantially at f/2 but the borders/corners remain very soft.
f/2.8 is still not great overall but there's a massive boost at f/4 where the outer image field is finally sharp. The best quality is reached around f/5.6 where the performance is actually quite remarkable. Diffraction has, as usual, a higher impact beyond f/11.
The field curvature is low. The centering quality of the tested sample was good.
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 on a low level with an average CA pixel width below 1px at the image borders. They do, however, increase quite a bit in the extreme image corners.
Bokeh
The resolution characteristic leaves something to be desired but what about the quality of the bokeh then? After all, that's probably the primary reason for you to be interested in such a lens.
Out of focus highlights are nicely rendered. At/near the image center, they have a perfect circular shape at f/1.4 and f/2. The inner zone shows a very slight onion-like substructure but it's hardly noticeable really. The more edgy aperture shape starts to show up from f/2.8 onward. You may spot the greenish halo around the discs - this is bokeh fringing (see also the next chapter).
The quality of the general blur is a bit of a mixed bag. In the background (shown to the left below), the rendering is somewhat uneven. The foreground blur (to the right) is smoother in comparison.
The circular shape of the discs is, as always, deteriorating towards the corners and the "cat eyes" at clearly visible at f/1.4 here. Stopping down reduces this vignetting effect but it's not too pleasant at f/2. It's better at f/2.8 albeit that won't help in terms of shallow depth-of-field, of course.
Bokeh Fringing / LoCA
Boheh fringing (sometimes referred to as LoCA) is an axial color fringing effect with purplish halos in front of the focus point and greenish beyond. The Samyang AF 50mm f/1.4 FE produces very pronounced fringing at large-aperture settings and traces remain visible at f/4.
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