invest in a better filter, you don't want a cheap one that will degrade the IQ on a good lens. have you try to compare using the 17-55 w/wo the filter on?
they shld do a EF-S 17-85 F 2.8 IS USM or a EF 17-85 F2.8 L IS USM. Heheheh. That zoom range is best. Wide and Mid Range Zoom. Add F2.8, IS and USM. Own liao. But sure need rob bank to get one. Maybe Tamron shld do that one. Replace the 17-50 and 28-75 together.
invest in a better filter, you don't want a cheap one that will degrade the IQ on a good lens. have you try to compare using the 17-55 w/wo the filter on?
Even the $$$, I would complement the 17-55 with a 70-200 f4 IS USM, but that is the max weight + no. of lenses I will seriously carry on a trip. Currently make do with the 55-250, but it's a little troublesome to change lenses, esp when you see the IQ drop from 17-55 to 55-250!