1) Type1: "If the film isn't good, I won't watch it."
1) Type2: "If the film wasn't good, I wouldn't watch it."
2) Type1: "If the weather may be ("is") good on Sunday, we may go for a picnic."
or: "..., we will go for a picnic."
2) Type2: "If the weather might be ("was") good on Sunday, we might go for a picnic."
or: "..., we would go for a picnic."