Disclaimer: I'm not a professional lens tester! I do this for my own interest and fun and I also just have a single exemplar of each lens. Please take this with a grain of salt.

This is a small and non-scientific comparison of the 14-24mm f/2.8 S versus the 14-30mm f/4 S.

Sadly I didn't own the 14-30 any more and I never took shots of my test scene at f/4. Therefore it's just f/5.6 to f/11 for the 14-30mm.

Additionally I added some example shots from the 14-24mm f/2.8 S, all hand held and not very scientific. But they should give an idea what someone could expect from this imho amazing UWA.

- Sharpness -
In the center the 14-24mm and the 14-30mm are head on head and I can not see much of a difference.

The 14-24mm is significantly sharper on the edges and in the corners already starting at f/2.8.

The corners of the 14-30mm at f/4 are mediocre at best. At least for my copy. And they never get clean/good regardless of how much one stop the lens down.

The 14-24mm shows the best at 14mm and the worst at 24mm whereas the 14-30mm is worst at 14mm and best at 30mm.

From my short experience I think the best apertures for the 14-24mm are f/4-f/8.

- Autofocus -
Fast and quite, nothing to add here.

- Bokeh -
Imho not too bad for such a wide lens, but the bokeh balls have a bright and well defined outline. Looks a bit like the bokeh of some vintage lenses.

- Flaring -
I had a hard time to provoke some flaring and even then it didn't show up much in the image. You can spot some flaring it in one of the example image below. But boy, this UWA does a amazing job here.

- Size and Handling -
It's almost the same size as the 24-70 f/2.8 S but 150g lighter. Build quality is excellent, everything works and feels nice and smooth. Nothing to complain.

- Filters -
Didn't to any testing here yet.

The 14-30mm for sure has a advantage on this topic.