Best source of filters is Camera Filters The Filter Connection 2filter.com for Hoya Digital filters, Hoya Pro 1, Tiffen 4x4 Camera Filters, B+W filters and Canon Inks

They have just about everything on the market and at all sorts of budgets.

many thanks for the advice maybe I'll just take off the filter before shooting.
canonmick

zooms are always a bit softer. Fixed focus are the sharpest of them all. before you buy ask the store to put it on your camera shoot something you will be doing in the store or outside... shoot a box to see if all lines are straight, shoot in different apertures and check sharpness. I deal with hundreds of pictures a day I see the results from crap stuff. Shoot in the light see if you get a lot of fog. go for the real premium glass...
a poor lens bought is something you will regret forever, or until you sell on e-bay for a loss.
Keep this one idea in mind "always"
there is only 1 thing between your subject and the CCD or CMOS ( film) that is the lens! all the rest is toys !
Happy shooting.
Peter

That really used to be true. The newest technology of zooms makes them just as sharp (or sharper) than the old days of fixed focus lenses and sloppy zoom lenses. Most Pros I know use zooms all the time. Your comment on no filters is true however. Outdoor Photographer this month has an article by several top pros on the zoom tele's they use just as evidence of what I say. There is still a place for fixed focal length lenses, but it is disappearing very quickly as new technology catches up.

I second that, Ross. The only reason I would reach for a fixed lens is when I need really wide apertures not available in zooms.

There is always going to be more distortion in zooms, but this is easily corrected by DxO Optics Pro.

Weng

Fixed focal length is still superior to zooms.
The difference between the two types has become less and less due to better quality and design, but the fixed focal length is still way better in the vast majority of cases. Zooms are very good and can be a good compromise for pros. Honestly most customers/clients will not be able to tell the difference if given two printed photographs of the same shot taken from two different lenses. But you or a pro could pixel peep on the computer monitor and easily see the difference as you start to examine the resolution, color and contrast and micro details.
The lenses are tools... you pick the best one for the job understand the compromises you are making and go with it.
The 300 2.8 is one of the finest lenses available, as is the Canon 200 1.8 arguably one of the finest lenses on the planet. The 70-200 2.8 IS is also a superb lens and is amazing in its detail. The 70-200 2.8 IS is a great choice for a zoom all depending on what/where/what available light there is and what you are shooting. If however you could use the 100 2.8 or the 135 2.0 for the same job, their resolution is even better.
Horses for courses, meaning choose the right tool for the job.
I would recommend you borrow or rent a variety of lenses and make your decision based on your needs and budget.
I have and use a wide variety of Canon lenses mostly the "L" lenses for everything from weddings, portraits, landscape, bird photography, and sports. Each and every lens has benefits and compromises.
Jim T