Do you recognize this movie? can you tell me its name?

Hi!

I was wondering, could you help me to find out the name of this movie.
It tells about a group of persons, I think they were two couples, being somehow transportes to another planet.

One of the men drew as a child a picture showing a vew from another planet, which had two moons. If I remember well, the boy found a kind of strange stone or cristal and took it to his bedroom. At night, while he was sleeping, he dreamed he was in that planet, and he painted what he saw in his dream.

When he become a man somehow he was transported with at least three persons to the same planet that he drew remembering what he saw in his dreams.
I think they were transported by the power of the cristal the child had found.

After they were in that planet for a while they got transported into a spaceship, where they experienced some kind of test.
In one ocasion a very big spider appeared in front of them and one of the women tried to feed the spider with something to eat, they had just found before they saw the spider.
At some point they had to fight against another kind of spaceships. They were loosing the battle when they decided the rescue themselves by geting transported back to Earth, after they jumped into something.
I remember that they appeared on Earth, in a country where they didn't speak english, but they were glad to be back on Earth :)

I saw that movie in the 70´s.

Thanks for the help you can give me to find this film!