Hi everyone. This is my first post, and would like your opinion!

I'm going to buy the k20d as my first dslr. As I'm at the beginning, I haven't got any specific predilection, even if I like to take panoramas, portraits, street photos.

As I have to buy a lens for a general use and also for my job, I was thinking to the Sigma 17/70 because should be better for low light indoor situations and it is a pseudo macro lens (but why the Pentax costs much more? maybe for the SDM lens motor? Is it that useful? or maybe it is only one more thing to break?)

In addition, as I like the practicity to use a unique lens, I was considering the Pentax 18-250 mm, that could help me alo sto learn, I guess. Is that the best one among his similar?

Or that focal lenght is a "duplicate" as I would have a 17-70, so it would better to practise with the 17/70 to buy a 50/200 or 70/200? and which one?
Thank you