Polarizing filters and wide angle lenses

[labaer]

I am interested in getting a circular polarizing filter for a Tamron SP AF17-50mm F/2.8 lens that lists a filter size of 67 mm. It will be on my DSLR that has an adjustment factor of 1.5, ie., this lens will have an effective focal length of 25-75mm.

I have noticed that B&H lists a variety of polarizing filters of this size, some of which call themselves "slim" filters. The features tab states that slim polarizing filters are for wide angle lenses. For example, some of them state that they are only 3 mm thick and have no front threads.

What is the importance of a slim filter for a wide angle lens?
Do I need a slim filter for the lens I described above?

Any advice would be appreciated.

Thanks,
josh

[Canuck935]

Thin filters for wide angle lenses are to prevent vignetting in the corners of the image. If you're a penny pincher/do it yourself type you can get a regular filter and if it causes vignetting on the wide end you can do your own 'modifications' to the filter. Personally, I just bought a thin filter for my wide lens

[labaer]

Thanks,
This sounds like good advice.