I don't see why you couldn't change filters with the hood attached on either of the Pentax hoods for this lens. A screw-in hood usually has another thread on the front that allows attachment of filters. The slide on hood slides right over the outside-front portion of the lens so it doesn't cover the inner threading of the lens barrel as long as it is pushed back far enough. While I can't say for sure because I never had either hood for this lens, I do have hoods for the two Mamiya 645 45mm lenses in my collection (the larger original and the smaller N version). Both hoods are the slide on type that fit around the outside of the end of the lens barrel and it is very easy to attach or remove filters with the hood in place.