How to know what size threads are on the front of a canon lens?

Question

How to know what size threads are on the front of a canon lens?

Answer 1

All lenses use the same type of threading, but some lenses are wider than others, so filters are different sizes. Find out the filter size of your lens (it probably says on the lens) and any threaded filter that you get will work (though, I suggest to stick with Hoya or Tiffen.)

In case it comes up, gel filters are NOT the same thing, and require a special holder. They might be more convenient, but they don't work so well. Stick with threaded filters