Laowa 9mm f/2.8 Zero-D - Review / Test Report - Analysis
Lens Reviews - Fujifilm X

Distortion

You may notice the "Zero-D" or zero distortion in the name of the Laowa lens. While you can spot a barrel distortion upon close observation, it is marginal really. It is especially worth mentioning that this was achieved without any digital auto-correction.

Note: Imatest is sometimes exaggerating the numeric distortion figures. Looking at the image we are probably talking about image distortions below 0.5% rather than the 0.8% that Imatest calculated there.

Vignetting

The Laowa 9mm f/2.8 Zero-D has one weakness - vignetting. It exceeds 4(!) EV/f-stops at f/2.8 and stopping down to f/8 reduces it to 2 EV.

While this may sound terrible - and it is certainly no good at f/2.8 (to the left below) - it isn't quite so relevant at medium apertures in real life. At f/8 (to the right below) the light falloff isn't fully exponential but relatively linear.

MTF (resolution)

The resolution characteristic of the Laowa 9mm f/2.8 Zero-D is decent. The center performance is actually outstanding at f/2.8 and decreases from there due to (normal) diffraction effects. The outer image field isn't quite on that level, of course. At f/2.8 the borders are still good but the corners are soft. Stopping down to f/4 boosts the corners to good levels already. The sweet spot is reached between f/5.6 and f/8 where the borders/corners are scratching the very good mark.

The centering quality of tested sample was good (we tested a prototype).

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)

The lateral CAs (color shadows at hard contrast transitions) are low with an average pixel width around 1px at the image borders. This is usually not disturbing.