What to do about different filter sizes?
Ideally, buy each of your filters once and use step up rings. It will save you lots of money. There is only one important catch with this approach and that is you cannot use lens hoods anymore except with the lenses that match your filter size. The second minor catch is you cannot use your filters on certain lenses that have built-in lens hoods. This tends to be the case of more specialized optics.
