Was made in 1961 and it has that generation of model moving across painting sort of special effects.
All the main cast are dead and gone now. Acting was awful but sort of expected from SciFi from the time.
Had two beautiful women Colleen Gray and Delores Faith and Dean Fredricks (spelling?) was lead.
Spoiler Alert!!!!! Don't read farther if you don't want plot points revealed..........
Different in that the story revolved around an asteroid (not a planet) that the lead astronaut runs into. As soon as he breathes the asteroid air he shrinks and finds other people living on the planet. He's amazed but the girl he meets matter of fact tells him each planet has it's own atmospheres and each inhabitant grows or shrinks to match that planets appropriate size. (Even by 1960s science, doesn't make much sense ). Of course he's stuck there and has to marry one of the two women eyeing him since he arrived. And of course, he picks the more virtuous one and they are instantly in love. There are also hilariously ugly bad creatures who attack them. The main one of those creatures was actually the guy who would later go on to play Jaws in the Bond films. Probably was cast because of his giant size.
The story although highly impossible was sort of entertaining to watch more to make fun of than to take seriously. Most early 60s and 50s SciFi were more horror than science.
Our hero finally regrows and is rescued by his fellow astronauts and choks it up to having hallucinated due to oxygen depreciation. Till he finds a crystal in his pocket from his tiny gf.