You've noticed a transformation in film style in 1958? V. interesting. Please elaborate and give examples of old vs. new. Thanks.
Not entirely specific to '58, it started a bit earlier but really starts to develop and grow in '58 and sets the stage for the changes to come in the sixties. The influence of TV style and more low budget indie producers like Roger Corman and William Castle is another factor as is simply the changing demographics and associated values of the era along with the decline of the old studio system, which I mentioned earlier in the thread.
It's essentially B movies finding a style that is more their own, though indebted to TV and earlier B's (particularly the so called noirs), and running with it to fit new "youth oriented" or anti-studio film subjects. While the "A" level studio pictures were wallowing in excess in their attempt to lure people from TV to the theaters, the low budget films start to adopt some of the methods of TV while maintaining a more cinematic sense of movement and action, to whatever degree they could afford it, and the dialogue and stories filmed in this manner were a good fit to the looks of the films as they too were trimming the fat of character development and leisurely tone setting to get to the excitement quicker, such as they may have had in any given movie.
Whether purposeful or not, the many films aimed at sub-groups, like teens or genre fans, seemed to work almost directly against the studio design as if setting up a alternative for new audiences. It isn't just in the US either. You can see the same thing happening in Japan, for example, with Suzuki and others adopting similar measures. It's almost a move away from one kind of sensibility of connection to character to one of incident first, which is what they sort of took from the "noirs" and other Bs of the forties while shooting more in the style of cheap 30s films or TV. They didn't rely on shadows to hide the cheapness of the sets and seedy locales, they just filmed then as part of the story, almost as an anti-aesthetic that developed into a look of its own. William Castle, for example, had been making movies since the 40's, mostly genre films like westerns and crime thrillers that didn't/don't get much notice, but he moved to horror films in '58 and found a match of subject and style that worked. Macabre was his movie in '58, which I've yet to see, but House on Haunted Hill in '59 exemplifies the change. Corman also started in older genres in the early fifties but found his match for style and subject in '57 or so, with a bunch of cheap teen and horror films that have a sort of ugly beauty to them notwithstanding their innate silliness. '58's She Gods of Shark Reef is flat out ugly by any previous film standard, but that ugliness has a sense to it that he would better develop as he went on. It suggests a world that isn't "picture perfect", where the base of the screen world is already deeply flawed, which the characters actions then have a different sort of sense to them for coming out of that milieu than they would in the standard Hollywood film.
Even some of the movies that were higher budget studio works that dealt with B subject matter, like The Fly and The Blob, were adopting different looks and framing for their stories to fit a new market and compete with TV by telling stories that weren't going to be part of on-going shows. Less family drama, which TV excelled at, and more movies challenging social norms or feigning to do so anyway, while filming the stories in ways that would still work for TV where they would eventually turn up on broadcast TV movie specials or late night shows. It was both a match to TV for efficiency a competition with TV for viewer and acknowledgement of the reality of the TV market needing movies for their channels. Mostly I'm sure there wasn't any plan for all this, just movie makers siphoning what they could from older films as concepts than adapting them to be new enough to use again while trying to maintain the interest of an audience who were familiar with the old forms and stories. That's the common element of art/movies/tv, the need to keep finding something new to keep audiences interested and/while recycling the old to keep things familiar enough to be understood. Every now and then the cycle tilts more towards the new than the old both because of demographic shifts, more young people, and because the old is getting too familiar so some more radical change needs to happen. '58 was one of those moments, but the shift wouldn't fully reveal itself until the early sixties when movies like Psycho started to hit the screen. The aesthetic I'm talking about sets the stage for that.
Sorry for some repetition with what I said earlier, but I don't have the time at the moment to go into more specific examples, I'd need to look at all the titles again to go more in depth with what I'm suggesting. And it's also not a suggestion anyone should seek out movies like She Gods on Shark Reef thinking they'll be great or something, it's just that movie happened to trigger some of the thoughts on the subject for me, so it comes to mind more quickly than others.