so bummed...

I am so bummed.  I messed up.  I did exactly what I was afraid I would do.  I ordered the wrong lens.  That "awesome zoom portrait lens" is not as awesome as I wanted it to be.  I wanted to be able to get a wide aperature (f2.8) and I wanted some zoom.  The other lens I got last year from my dad goes down to f1.8-- but no zoom.  It's hard to have the camera right up in someone's face.  So--that's why I wanted the other one,got advice from photography friends, talked to the guy repeatedly at Sigma (generic lenses basically.)  As I have been using it, I notice that when I zoom my aperture changes- number goes up which means I am not getting that background blurred out like I want.  It has been nagging in my mind and I have been meaning to try to investigate it- sure there is a scientific reason and my limited mind couldn't recall it.  Finally, last night I googled a question of sorts about it and come to find out: it's the wrong lens.  Mine says the focal length 17-70 and then f 2.8-4. That means the aperture can range from 2.8-4.  It will only be 2.8, though, at its shortest focal length.  That means, if it is zoomed to 70mm, you are NOT going to get a wider aperture than 4!! No wonder my portrait on the dock didn't fuzz out spider webs and dirt, etc.  Grr.  After some searching, I have discovered that knowledgeable people know you don't want to see that range printed on the lens.  The one I should have gotten is: 17-70 2.8(period, no dash 4!!)  I wish Mr. Know-it-All with the British accent had MENTIONED that on the phone! The right lens is about $170 more, but I would have done it and just not have gotten the accessories.  Well, that's a sore subject too, because the lens hood I purchased from amazon for $25 is stupid.  It leaves black corners on the frame of my pics- and I didn't know that until right before my shoot with my niece so I had to take it off and that is why there is a huge green ball of flare on one of my favorite shots!  Now what do I do? :(  My lack of knowledge wasted money.  Same story with my landscaping- 2 basically dead shrubs after I splurged on trying to make things look less neglected.  ho-hum....