I'm afraid of buyer's remorse on this one and was wondering if anyone else has an opinion on the lenses I'm interested in.... I'm doing more portrait photography and child photography; I was wanting to get a nice lens just to step up the image quality. I would love to get the Nikkor 28-70 but it's over $1500, and I'd thought maybe the 28-75 Tamron would be comparable. But is it? Would anyone recommend waiting a while to invest more in a better quality lens or have you found that the price difference isn't worth it? I am getting constant calls from Ritz camera because I'd started to make the Tamron purchase online and backed out at the last minute; I'm afraid to pay for a $400 lens and find out I am going to want the Nikkor in a few months when I can hopefully afford it. I have the 50 mm f/1.8 that could probably do the job in the meantime, but when the time comes to make the purchase, I just want to know if that extra $800 difference is worth it. What do you think?