[newbie] troubles with tuples

[Jean Dupont]

I'm looking at the way to address tuples
e.g.
tup2 = (1, 2, 3, 4, 5, 6, 7 );

As I found out indices start with 0 in Python, so 
tup2[0] gives me 1, the first element in the tuple as expected
tup2[1] gives me 2, the second element in the tuple as expected
now here comes what surprises me:
tup2[0:1] does not give me the expected (1,2) but (2,)

what is the reason for this and how then should one get the first and the second element of a tuple? Or the 3rd until the 5th?

thanks in advance and kind regards,

jean