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Distortion
Typical for most tele zoom lenses the Panasonic produces a low level of distortion. The lens shows slight to moderate pincushion distortion between 0,35% at 45mm increasing to 1,6% at 90mm and dropping below 1% at the maximum zoom range. This is nothing to worry about in field conditions especially for Panasonic users due to the automatic distortion correction.
If you move your mouse cursor over the image you can switch to the corresponding non-corrected results.
Vignetting
The telephoto lens has an average vignetting characteristic. The following figures show the corresponding performance of auto-corrected JPEGs obtained straight from the camera compared to non-corrected raw files.
The focal length between 80 and 175mm shows only slight vignetting. However, at 45mm and wide open aperture the amount of vignetting is very pronounced at ~1,1EV which is easily noticeable in field images. Nevertheless, vignetting it's not really an issue anymore from f/8 onwards. Furthermore the non-corrected (RAW) images show slightly worse results.
The following graphs compare the vignetting characteristic of auto- and non-corrected files between 45 and 175mm from open aperture to f/11.
The following images illustrate the above mentioned heavy vignetting at 45mm.
MTF (resolution)
The Panasonic lens produced good to very good resolution figures in the MTF lab which is certainly decent considering its focal length range. The performance is best at 45mm with a very good quality across the image field. There's a slight decrease in performance towards 80mm and slightly more so at 120 as well as 175mm.
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)
A good news is the low amount of lateral CAs (color shadows at harsh contrast transitions) - at least when shooting JPEGs or using mainstream RAW converters. These color shadows are negligible throughout the whole focal length with an average CA width of around ~0.4px at the image borders.
However, the non-corrected RAWs show a different situation with an average CA width of around ~0.7px at 45mm and ~1.7px at 80mm & 120mm. Interestingly the CAs decrease a bit again at 175mm (~1.1px). This can be visible on Olympus cameras where the RAWs are not auto-corrected in this respect.
The following figures show the corresponding performance of auto-corrected JPEGs obtained straight from the camera compared to non-corrected raw files.
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