Olympus 9mm f/8 Fisheye Lens Cap - Review / Lens Test Report - Analysis
Lens Reviews - (Micro-)Four-Thirds

Distortion

Fisheye lenses produce massive distortions by design - this is not a bug but a feature here. Unfortunately the lens is only capable of showing an angle-of-view of 140 degree which is less than the 180 degree in conventional fisheye lenses. The fisheye effect is therefore not quite as pronounced.

Our analytics tool wasn't able to come up with a figure for the fisheye distortions thus we are just showing the test grid below "as is".

Vignetting

Despite the fixed aperture, there's quite a bit of light falloff (~0.9EV). This is not dramatic but it'll be visible scenes although this is still not relevant in the context of a fisheye lens for sure.

MTF (resolution)

The resolution characteristic of the 9mm f/8 fisheye is acceptable. The image center is actually pretty sharp and the borders aren't all that bad. However, the corner performance is rather dismal by conventional standards. The corner quality is not shown below - there was just no reliable way to measure the corners but expect something around the 1000 LW/PH mark here. The contrast level is generally quite low but especially so in the corners.

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 hard contrast transitions) aren't too extreme but visible with an average pixel width of 2px at the image borders. However, expect higher figures in the image corners.