The kit lens or other 14mm with the WWL-1 has barrel distortion too
The only options for rectilinear are the 7-14mm or the 8-18mm or the 9-18mm behind a semidome
None of those lenses are stabilised the olympus 9-18mm is the cheapest and only requires a 4” wide port. At widest setting it gives you around 100 degrees fov which works well for everything.
Alternatively you can reuse the Inon UWL-H100 you already have this will give you the same field of view of the 9-18mm but will take advantage of 5 axis stabilisation. From optical point of view this is not as good as the WWL-1 and it does have some fringing on the edges however in combination with the other UCL-165 you already have will give you an all in one set up and if you get the power zoom lens the same feeling when you zoom in for close ups to the sony
If I were you I would take it in steps and start there instead of investing immediately in a port system
Take also into account that for video use the 14-42mm focal range is more useful than a 60mm macro or a wide zoom as you do portrait work in the 35mm-84mm range with lights and you then add diopters for macro work
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