skimini, I have the Tamron 17-50mm f/2.8 and it's brilliant. It's the lens I use most often. It out performs the kit 18-55mm in low light as its widest aperture is constant throughout the zoom range. The only disadvantages are that it is big and heavy (which doesn't bother me) and that the built in flash is obscured by the lens hood and barrel at wide angels. Also not a problem as I have an external flash. I don't have the 28-75mm, so can't comment on this lens except to say the obvious, that it has a narrower angle of view, which may be a little restrictive in tight situations.
Can you upload some pictures taken from your 17-50mm? I'm trying to set aside my two kit lenses and was thinking of using my 50mm f/1.8g and adding another lens, possibly the Tamron 17-50mm. Does it make any sense having 50mm lens and a 17-50mm? I will mostly do street photography.
Comments
I don't have the 28-75mm, so can't comment on this lens except to say the obvious, that it has a narrower angle of view, which may be a little restrictive in tight situations.