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Laowa 85mm f/5.6 2x Ultra Macro APO - Review / Test Report - Analysis |
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Lens Reviews -
Sony Alpha (Full Format)
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Page 2 of 3
Distortion
The Laowa 85mm f/5.6 2x Ultra Macro APO is basically free of image distortions - even without auto-correction (which isn't available with this lens anyway).
Vignetting
The vignetting is fairly uniform across the aperture range with a light falloff of about 1EV (f-stop) at f/5.6 and just slightly less than that when stopped down.
MTF (resolution)
The Laowa lens does a good job in terms of resolution without being able to excel. One reason for this is that the lens is diffraction-limited at f/5.6 already (on high megapixel sensors at least). The typical peak quality on full format cameras tends to be around the f/4 mark and f/5.6 is obviously slower than this. However, the quality is quite uniform between f/5.6 and f/11 with a very good center and a good to the very-good outer image field. f/16 remains usable but f/22 should be avoided. Please note that this is for the quality at conventional focus distances. The results will differ with extreme close-ups but that's nothing we can reasonably test in a formal procedure.
The field curvature is low. The centering quality of the tested sample was Ok. A perfect sample would have probably been a little better at f/5.6.
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 (color shadows at the image borders) are very low between f/5.6 and f/11 but increase at f/16 and, more so at f/22. However, the CAs are still moderate even at f/22.
Bokeh
If you are into macro photography it is almost inevitable that most of your scene is blurred due to the shallow depth-of-field. Even the 85mm f/5.6, while not impressive in this respect at conventional focus distances, qualifies here - especially when approaching its max magnification of 2:1 where the DOF is hair-thin. So how is the quality of the bokeh (out-of-focus blur)? It's a bit of a mixed bag.
As you can see below, the highlight rendering isn't really ideal. While circular at f/5.6, the discs become edgy at f/8 already. And the inner zone of the discs is fairly busy.
When looking at the full image field, you have a medium-sized zone in the center where the circular shape is maintained before highlights are transitioning to ellipsoid shapes at the borders and corners.
At f/5.6 the overall characteristic is still quite pleasant though. Stopped down to f/8, the outer "discs" look rather distorted due to the combination of the edgy and ellipsoid shape.
The "discs" are more uniform from f/11 onward.
While the highlight rendering didn't impress, the quality of the general blur is very smooth in the image background (shown to the left below). The foreground is just a tad less silky but still very good.
Bokeh Fringing / LoCA
Laowa is advertising the lens as an "APO" lens hinting that LoCA (axial CAs) are well controlled. We wouldn't fully sign this off - below is a sample image with crops illustrating that purple/green color fringing is still present at f/5.6.
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