Actually most of the female characters on TOS were shot with soft focus. TOS's director of photography, Jerry Finnerman, was trained by the generation of cinematographers that had honed their craft in the age of black-and-white movies and film noir, which is why TOS makes such heavy use of patterns of light and shadow. There were certain rules he was trained to use, rules I remember him enumerating in a Cinefantastique interview I read once. They included: Always shoot women in soft focus; always front-light women to smooth their features and cross-light men to sharpen theirs; and never angle a camera up a woman's nostrils because it's unflattering. Basically, make every woman as glamorous and ethereal-looking as possible, while making the men look tougher and harder-edged. Finnerman used the same techniques with Bruce Willis and Cybill Shepherd on Moonlighting many years later.