Wide angle lenses

[Hadley]

By its very nature a UWA will have barrell distortion and it's not neccesarily a bad thing. It depend on what you want to shoot.

Probably just landscapes

 

[Digifrog]

Probably just landscapes

In that case the only thing the w/a distortion will give is a slight bowed horizon (if doing seascapes). This can be avoided by placing the horizon across the middle of the frame, and if it happens to be in the top 3rd it will be negligable and easily corrected if you have software.