I remember reading in a “Making of Star Trek” book that one of the ways the series saved money was limiting the color palette used in sets and costumes. The series was filmed in color, but most people still had black & white TV sets. So the ST folks chose colors for sets & costumes that were still distinct when viewed on a B&W screen. For example, rather than paint a set wall with several subtly-differing shades of red, they’d just paint it all one red - a big time saver.
As I recall one of the production people had a filter that would show what the scene would look like in B&W. If the sets/costumes looked OK when viewed through a camera using this filter, they’d stop adding detail or other colors.
Sorry, no cite, just my middle-aged ST-obsessed memory.
“The Cage” had to be originally filmed in color. The last prime time show on NBC that was broadcast in Black and White was the first season of “I Dream of Jeannie” in 1965-66.* In the 1966 season, Jeannie went color, and NBC boasted about having an all-color lineup. If you wanted to sell a show to NBC for the 1966 season (the year Star Trek premiered), you had to shoot it in color; NBC wanted that “all color lineup” brag.
*A second show whose name I don’t recall premiered in 1965 in B&W, but didn’t last the season.
It was always filmed in color. I remember reading somewhere (Making of Star Trek?) that they had problems with Menagerie because they made the Orion slave girl green and the developing crew kept making her normal colored, so they’d make her greener and greener, until they actually talked to the developers. Unfortunately, I’ve gotten rid of all my Star Trek books so I can’t give you an exact quote.
^^^The color tests you mention were actually done on Majel Barrett, GR’S kept woman at the time, later his wife. The story is in “The Making of Star Trek,” though it was only later revelaed that it was actually Majel they had to keep painting greener and greener, not Susan Oliver. There are several photos of Majel in the green make-up and funky eyebrows floating around on the net.
The Cage was the first pilot, and so was done a lot before then. Where No Man Has Gone Before was the second pilot. I can look up when these were filmed, but I’m sure The Cage was done in '65.
That said, NBC made a big deal about its shows being in color (remember the peacock) so an hour-long drama would definitely be filmed in color.
We (and my friends) had black and white TVs, and it looked fine that way. The first ST I saw in color was “The Immunity Syndrome” at my well-to-do Aunt and Uncle’s apartment in Washington in the summer of 1968.