We guess if we were going to fuck our husband's best friend on film, we'd want to use a fish eye lens, too. It turns any hot blowjob into a hot blowjob filmed by Puff Daddy in the 1990s.
And then when the husband comes home and sees the video evidence, he's not concerned with the big, veiny, restrained cock splitting his wife in two; he's just excited about the production quality.