Have Canon A640 Digital Camera with lens adapter what type of polarizing filter do you use?

Believe there are 2 types circular is one. I was going to put it on end of lens adapter.

You need a circular filter that moves with the focus system.
The parallel filter will work but can give an uneven image as the filter is meant to stay square on to the lens.
Go for as good a filter as you can afford, look at eBay and seven day shop .com for one

You need a circular filter for digital.